Fuel Injection System - Diesel Buick Electra Estate Wagon

COMPONENT TESTING

Note. Specific component testing information not available. Refer to any tests performed during REMOVAL & INSTALLATION or OVERHAUL procedures

DESCRIPTION

General Motors V6 and V8 engines use a mechanical high pressure rotary pump, gear driven by the camshaft at camshaft speed. It injects a precisely metered amount of fuel to each cylinder at the proper time. The pump is mounted on top of the engine and provides necessary timing advance under all operating conditions.

High pressure fuel lines (6 or 8) carry fuel from pump to an injection nozzle in each cylinder. All lines are exactly the same length to insure that there is no variance in timing. Engine RPM is controlled by a rotary fuel metering valve. As accelerator pedal is pushed down, throttle cable opens metering valve to allow increased fuel delivery. A built-in low pressure transfer pump delivers fuel to main injection pump.

A fuel filter is located between the fuel supply pump (mounted on side of engine block) and the fuel injection pump. Any excess fuel is returned to tank by a fuel return system. An optional diesel fuel heater is available for cold weather operation.

AIR INDUCTION SYSTEM

An air crossover housing is located on top of engine over injection pump. It serves as the only air inlet in the system. No fuel passes through crossover. It is an open-chambered housing with a single inlet drawing air through an air filter assembly mounted above. The EGR valve is mounted in the air intake of the crossover housing on all but VIN T engines.

Crossover unit has 2 branches, one leading to each side of intake manifold. Gaskets are installed between crossover and manifold to prevent vacuum leaks. Starter fluid should NEVER be used or sprayed into crossover. If crossover is removed, air screens must be installed.

Diesel Injection Pump Fuel Circuit Diagram. Scheme 44

FUEL TANK-TO-PUMP SYSTEM

Diesel fuel is drawn from fuel tank by an engine mounted electric fuel supply pump. Pump receives battery current when ignition switch is in "RUN" or "START" positions. Delivery pressure to fuel injection pump is 5.5-6.5 psi (.39-.46 kg/cm 2 ). Maximum operating current is 3 amps. A small screen type filter is located in fuel tank at the fuel pick-up. A larger fuel filter is located either in the engine compartment (NB9 Fuel Filter System only) or on rear of engine between fuel supply pump and fuel injection pump. Diesel fuel arrives at center inlet fitting on injection pump after leaving filter. A fuel return line is provided to return any excess fuel to tank.

Diesel Injection Pump. Scheme 45

DIESEL INJECTION PUMP

High pressure diesel injection pump is mounted to top of engine below air crossover. Pump is cam driven at camshaft speed and can precisely govern time and amount of fuel injection.

Fuel entering the injection pump flows to the transfer pump and pressure regulator suction side. Fuel under transfer pressure now flows in 2 directions: to pressure side of pressure regulator, and to the head passage. The head passage will in turn divert fuel to the metering valve, pressure tap hole plug, advance mechanism, and the vent wire assembly.

The vent wire assembly allows air and a controlled amount of fuel to escape to the housing where it will flow back to the fuel tank via return oil circuit. Vent wire assembly consists of a screw with a hole through it into which a wire is positioned. Wire is free to vibrate and resist plugging by debris. Fuel from vent wire assembly circulates in the housing to cool and lubricate the internal pump components.

The metering valve controls fuel flow to pumping plungers. As pump shaft rotates, fuel is fired, under high pressure, through each delivery pipe to an injector. Pump is not serviceable and must be exchanged in case of a malfunction.

INJECTION NOZZLES

One injection nozzle is located in each combustion chamber. It has a single fuel inlet fitting and is threaded into cylinder head. Injection nozzles are spring loaded and calibrated to open at specified fuel line pressure. Combustion chamber end of injector has a replaceable copper compression seal. Inlet fitting in body of injector must be tightened to specified torque when installed or checked.

V8 injectors may be identified by a Blue color band, while V6 injectors use a Red color band. If band is missing, identify injector by part number stamped on injector body hex. Number 403 is a V6 nozzle and 404 is a V8 nozzle. (Scheme 46)

Diesel Injection Nozzle Identification Note presence and color of color band, if equipped. Scheme 46

GLOW PLUGS

The glow plugs are small heaters provided to assist in cold starting. Glow plugs have been redesigned to have PTC (Positive Temperature Coefficient) properties (low resistance at low temperature and high resistance at high temperature). The glow plug module controls all circuit functions.

Diesel Glow Plug & Injection Nozzle Location. Scheme 47

GLOW PLUG CONTROLLER

Glow plug module controls glow plug system in 3 steps: pre-glow, after-glow, and off. During pre-glow, the circuit turns on the "WAIT" lamp and heats glow plugs until they are hot enough to start the engine. During after-glow, circuit turns off "WAIT" lamp and keeps power applied to glow plugs. When engine is turned off, module cuts off current to glow plugs.

A set of thermal controls in the module govern pre-glow and after-glow operation by sensing engine temperature. Module also has an over-voltage feature which protects glow plugs from battery voltage higher than 14 volts. Module is located on the left rear side of engine.

HOUSING PRESSURE ALTITUDE ADVANCE (HPAA)

The HPAA solenoid, located in-line in the fuel return line, controls injection housing pressure. A drop in housing pressure causes an advance in timing. The HPAA/EGR altitude control switch for C Series with internal EGR is located under the A/C accumulator assembly bracket. For all others, HPAA is controlled by the Electronic Control System. In order for the HPAA to regulate at its calibrated value, the HPCA must be energized with its plunger extended holding the housing pressure regulating check ball off its seat. The HPAA housing pressure regulator, located in the outlet side of the HPAA solenoid, is adjustable. See Adjusting HPAA in this article.

HOUSING PRESSURE COLD ADVANCE (HPCA)

The HPCA is used to improve cold starting and emission control. Located in the top of injection pump, the solenoid advances injection timing by about 3-4° when engine is cold. Timing is advanced by decreasing housing pressure. At the same time, fast idle solenoid is activated. The HPCA solenoid is controlled by a temperature switch on the left rear head bolt of C Series with internal EGR and by the electronic control module in all others. The HPCA housing pressure regulator, located in the pump cover with an additional fitting that adapts it to the fuel return pipe, is adjustable. See Adjusting the HPCA in this article.

METERING VALVE SENSOR

The metering valve sensor is a variable resistor that sends a metering valve position signal to the diesel Electronic Control Module. This system governs EGR valve operation.

STARTING INDICATOR

Lights are used to indicate when vehicle is ready to be started. A "WAIT" lamp is lit when glow plugs are heating. As combustion chambers reach starting temperature, "WAIT" lamp goes off, indicating that engine can be cranked to start.

FUEL FILTER & WATER-IN-FUEL INDICATOR

Diesel vehicles are equipped with an indicator lamp to warn of water contamination. Two different fuel filter and water-in-fuel detector systems are used on the V6 models.

1. The first type has fuel filter located between the fuel pump and injection pump. If the element becomes plugged, the engine will stop. The water-in-fuel detector is attached to the fuel tank unit. Filter and fuel line heater (optional) are in engine compartment.
2. Second type (also used on all V-8 models) has all three components in the engine compartment and is called the NB9 assembly. The main, spin-on type filter incorporates a probe that detects water in the bottom of the filter. When the probe touches water, the "Drain Fuel Filter" light will come on. The NB9 fuel filter should be drained at each oil change. This system also has an in-line filter that is not part of the assembly.

DIESEL FUEL HEATER (OPTIONAL)

This option is used to heat fuel when ambient temperature is below 20°F (-7°C). This prevents wax crystals from building up and blocking fuel filters. Filter is located along right side of intake manifold (left side on V6) and uses a resistance wire spiralled around fuel line.

TROUBLE SHOOTING

Note. For additional diagnosis information, see DIESEL ENGINE TROUBLE SHOOTING in the ENGINES section.

GLOW PLUG SYSTEM DIAGNOSIS

Note. When trouble shooting, glow plug control must be operated when engine temperature is below 140°F (60°C).

No "WAIT" Lamp (Cold Engine)

1. With engine off and ignition switch in "RUN" position, check if charge light is on. If not, check gauges fuse. If gauges fuse is good, check for break in Pink/Black wire between fuse block and splice.
2. Unplug connector of glow plug controller. Using a jumper wire, connect Dark Blue wire at connector to ground. If "WAIT" lamp does not go on, check for burned out bulb.
3. Check for break in Dark Blue wire between "WAIT" lamp and glow plug controller, and also in Pink/Black wire between "WAIT" lamp and splice.
4. Check connection at ground. Connect 1 end of test lamp to Red wire terminal of glow plug relay and other end to ground. Then touch lead to Black wire at glow plug controller. If light comes on, replace glow plug controller assembly.

"WAIT" Lamp Stays On More Than 15 Seconds

1. Ensure battery is fully charged. Turn ignition to "RUN" and "OFF". Listen for click to check glow plug relay operation. If relay OK, replace glow plug controller.
2. If glow plug relay doesn't operate, check diesel fuse. Unplug connector at glow plug controller. Attach test light between pins "B" (Pink/Black wire) and "C" (Black wire) at harness connector.
3. Turn ignition to "RUN" and check for battery voltage at Pink/Black wire. If test light does not glow, check continuity of Pink/Black wire.
4. If test light comes on, check continuity (less than 75 ohms) between pins "B" and "C" of glow plug controller. If no continuity, replace glow plug controller.

Engine Does Not Start When Cold ("WAIT" Lamp OK)

1. Check that cranking speed is 100 RPM or more. If less, check battery voltage with voltmeter (12.4 volts with ignition off).
2. Using test light, check for voltage at Pink wire lead at fuel solenoid of fuel injection pump with ignition switch in "RUN" position. Repair Pink wire if no voltage.
3. If test lamp comes on, turn ignition off. Using self-powered test lamp, check for continuity through fuel solenoid to ground. If no continuity, replace fuel solenoid.
4. Check glow plug relay. With ignition on, test for voltage between Green wire post of glow plug relay and ground.
5. If test light doesn't come on in previous step, touch harness connector to ground. If light comes on, replace glow plug. If light doesn't come on, replace wire to glow plug.
6. If relay operates, turn ignition switch off. Unplug all glow plug harness connectors at glow plugs. Connect self-powered test lamp between Green wire post of glow plug relay and ground.
7. At each glow plug, touch harness connector to glow plug spade terminal. If test lamp comes on, glow plug and harness lead are good. Unplug harness connector after testing each glow plug. After test, reconnect all glow plugs.
8. If test lamp does not come on, touch harness connector to ground. If lamp comes on, replace glow plug. If lamp did not come on, replace wire to glow plug. If all glow plugs are open-circuited, also replace glow plug controller.
9. If relay does not operate and "WAIT" lamp went on and then off, check circuit of glow plug controller and relay. Remove glow plug controller assembly from vehicle. Disconnect glow plug relay and check continuity of both.

Engine Cranks Normally But Will Not Start

1. Be certain correct starting procedure is being used and that glow plug system is operating.
2. Remove any glow plug and, by cranking engine for 5 seconds, determine if there is fuel to the cylinders. If so, check for incorrect or contaminated fuel.
3. If there was no fuel, the fuel return system may be plugged. Disconnect fuel return line at injection pump; connect hose to injection pump connection. Route both into a container. If engine starts and runs, fuel return lines are plugged. If engine doesn't start, check to see if injection pump is clogged.
4. Check to see if there is fuel to the injection pump by turning ignition switch "ON" and opening water drain valve on end of hose into a container. Fuel should spurt when drain valve button on fuel conditioner is pressed. If it does, fuel supply to pump is adequate, but shut-down solenoid is faulty.
5. Check for restrictions in fuel filter. Also check fuel pump operation. Fuel should spray from the line going to the filter when line is disconnected.
6. Check for voltage at the fuel solenoid. Voltage should be 9 volts. Other sources of problems for "no start" condition are low compression, incorrect pump timing or injection pump malfunctions.

Engine Starts But Will Not Continue To Run

1. Adjust slow idle. Check fast idle solenoid. It should move to hold injection pump level in fast idle position. Check for restricted fuel return system. See No. 3 above, checking the HPAA solenoid also. Also, be certain the return line check valve fitting from the top of the pump isn't plugged.
2. Be certain glow plugs are not turning off too soon. In addition, check for limited fuel to injection pump, incorrect pump timing, pump malfunction, or fuel solenoid closing in run position.

Engine Surges At Light Throttle Under Load.

Torque converter clutch may be engaging too soon. Timing may be retarded. Fuel filter may be plugged. Injection pump housing pressure may be too high or line volume too low. There may be an injection nozzle with low opening pressure.

Initial Idle Only is Rough With Excessive Noise Or Smoke

1. Be certain correct starting procedure is used and engine break-in time (2,000 miles) is sufficient.
2. Then check for inoperable HPCA, glow plug, or nozzles. Also check injection pump timing and for air in system. Install a section of clear tubing on the fuel return fitting from the engine and watch for bubbles.

Engine Misfires Above Idle But Idles Correctly

Check for plugged fuel filter, incorrect injection pump timing or incorrect, contaminated fuel.

Engine Will Not Return To Idle

Be certain external linkage is not binding or misadjusted. Check fast idle adjustment and injection pump for malfunction.

Loss Of Power

1. Check air cleaner and fuel filter. Check for restricted exhaust or fuel supply from tank to injection pump. Check for restricted fuel return system. Check for plugged fuel tank vacuum vent in fuel cap. Fuel cap should not hiss LOUDLY when removed.
2. Check for external or internal compression leaks. Check timing, fuel type and quality. Check for injection pump and EGR/EPR malfunction.

Rapping Noise From One or More Cylinders

A noise similar to connecting rod bearing knock can be caused by nozzles sticking open, or having very low opening pressure. Piston offset could be wrong, or piston could be hitting cylinder head.

Loud Combustion Noise With Excessive Black Smoke

Timing may not be set correctly. Injection pump housing pressure may be wrong or there may be an internal problem with pump. EGR/EPR may be malfunctioning.

Normal Combustion Noise With Excessive Black Smoke

Timing may be incorrect. EPR may be malfunctioning. Injection pump may need calibration. Check for restricted exhaust or low opening pressure of injection nozzles.

Poor Fuel Economy

Owner's driving habits may be bad. A/C may be malfunctioning. Air filter may be clogged. Timing may be incorrect. Also check for fuel leaks, incorrect speedometer or bad transmission.

Engine Will Not Shut Off With Key

Injection pump fuel solenoid does not return fuel valve to "OFF" position. To turn off engine, pinch fuel return line at the flexible hose. Disconnect Pink wire from solenoid. If engine shuts off, there is an electrical problem. If engine continues to run, fuel shut-off linkage is stuck.

ROUGH ENGINE IDLE

1. Remove air cleaner. Install Mag-Tach (J-26925) and check engine idle speed. Reset if necessary. See appropriate article in TUNE-UP Section. Check the injection pump timing. Adjust if necessary.
2. Examine injectors for leaks at body or at fuel line connection with engine running. Check for leaks at injection pump-to-high pressure lines. Correct any leaks.
3. Perform fuel pump pressure and flow tests. See Testing in this article. Correct any defects in fuel delivery system.
4. Remove fuel return line from top of pump. Install short piece of clear plastic tube between return line. With engine running, check for presence of bubbles or foam in tube. Repair any air leaks in system.
5. With engine running, loosen fuel line at an injector to bleed a small amount of fuel from the line. If solid fuel appears, check next injector. If foam appears, shut engine off and remove line from injector.
6. Move line so that inlet to the injector can be observed. Remove Pink wire to the pump and crank engine. Check injector inlet for bubbles. If bubbles are present, remove injector for testing. Replace if defective.
7. If no bubbles are present, connect fuel line and Pink wire. Check remaining injectors in same manner. If engine still idles rough, perform Glow Plug Resistance Procedure.

Note. Rough Engine Idle diagnosis procedure must be performed before Glow Plug Resistance Procedure. Manufacturer recommends the use of Kent-Moore High Impedance Multimeter (J-29125A) for accurate test results.

Glow Plug Resistance Procedure

1. Engine must be at normal operating temperature. Remove all glow plug wires. Unplug alternator 2-lead connector. Using injection pump idle speed screw, adjust idle to roughest speed not exceeding 900 RPM. Allow engine to run for 1 minute.
2. Attach jumper wire between voltmeter ground lead and fast idle solenoid on fuel injection pump. DO NOT use any other point for ground connection. This ground connection must remain connected until all tests are completed.
3. Check resistance by touching positive lead of voltmeter to glow plug terminals (with engine running). Write down values obtained in firing order sequence. V6 fires 1-6-5-4-3-2 and V8 fires 1-8-4-3-6-5-7-2.
4. If equipped with electric cooling fan, record resistance values with cooling fan not running. DO NOT disconnect fan electrically. Resistance is dependent on cylinder temperature and indicates output of each cylinder.
5. If ohm reading on any cylinder is about 1.3-1.4 ohms, make a compression check on that cylinder before continuing fuel injection diagnosis. Correct cause of low compression before proceeding.
6. Normally, rough engines will have a difference of .4 ohms or more between cylinders in firing order. Readings may be changed by selection of injectors.
7. Remove injectors from cylinders in which resistance is to be changed. Determine opening pressure of injector. Also check injector for leakage and spray pattern. See Injection Nozzles in this article.
8. Install injectors with a higher opening pressure to lower ohm reading. Install injectors with a lower opening to raise ohm reading. A change of about 30 psi (2.1 kg/cm 2 ) in pressure will change reading by about .1 ohm. NOTE: A leaking injector will allow more fuel into a cylinder, which will raise glow plug ohm reading. Next injector in firing order will be starved for fuel, causing that glow plug to have a low ohm reading.
9. If a glow plug gives a low reading which does not change with injector change, then switch glow plugs between a good and a bad cylinder. If reading of each cylinder is not the same as before the switch, then glow plug can not be used for rough idle diagnosis.
10. Whenever an injector is cleaned or replaced, crank engine with injector installed and fuel line disconnected. Watch for air bubbles at injector inlet. If bubbles are present, replace injector.
11. Connect all fuel lines. Start engine and check idle quality. If idle is still rough, repeat steps 1) through 9). Ensure tests are made at same RPM as originally.
12. Idle quality will normally be restored after completing 2 series of resistance checks and injector changes.
13. Replace fuel injection pump if cylinder ohm readings do not change when injectors are changed. Also, replace injection pump if problem cylinder moves from cylinder to cylinder as injector changes are made.

HPCA & HPAA SYSTEMS

The HPCA and HPAA are designed to work in conjunction to control injection timing by altering injection housing pressure. Refer to Injection Housing Pump Timing Control chart to determine if system is functioning correctly.

INJECTION HOUSING PUMP TIMING CONTROL

FUEL PUMP

1. Disconnect fuel line between fuel pump and filter. Place end of fuel line in measuring container.
2. Turn ignition switch to "RUN" position. Pump should supply 1/2 pint (1/5 L) in 15 seconds. If not, disconnect inlet hose at pump and connect a vacuum gauge.
3. Turn ignition switch to "RUN" position. Vacuum must be 5.3 in. Hg. If less, replace pump. If more, check fuel lines for splits, leaks, or kinks.

Without NB9 Fuel Filter Assembly

This system uses a detector mounted inside the fuel tank on the fuel gauge sender. When 1-2 1/2 gallons of water are in the tank, the water-in-fuel light will come on. It will also come on for 2-5 seconds each time ignition is turned "ON". If water is present in fuel, the light will come back on after 3-6 seconds and remain on.

1. If water-in-fuel light is on at all times, turn ignition "ON" and disconnect 2 wire Yellow/Black-Pink connector at rear of fuel tank and check water-in-fuel light. (E Series, Yellow/Black is a single connector). (Scheme 48)
2. If light is on, locate and repair short to ground in Yellow/Black wire from 2 wire connector to IP water-in-fuel lamp. If light is off, drain fuel tank. See Fuel Tank Purging Procedure in this article. Connect 2 wire connector. (E Series Yellow/Black is single wire connector.) Check water-in-fuel light.
3. If light is on, remove fuel gauge tank unit and check for shorts. If none are found, replace detector. If light was off, fuel has water in it.
4. If water-in-fuel light does not come on during bulb check, turn ignition "ON" and disconnect 2 wire Yellow/Pink-Black connector (E Series Yellow/Black is a single wire connector) at rear of fuel tank. Ground the Yellow/Black wire to the body harness and check water-in-fuel light.
5. If light is on, remove fuel gauge tank unit and check Yellow/Black wire for opens. Check connections to water-in-fuel detector and be certain mounting screw is tight. If no problems are found, replace water-in-fuel detector. If light is off, check water-in-fuel bulb. Then check for open in Yellow/Black wire at rear of tank to IP water-in-fuel lamp socket.

With NB9 Fuel Filter System

1. If "Drain Fuel Filter" indicator is on all the time, drain fuel filter. If indicator is still on, disconnect the pigtail connector at the fuel filter assembly and check the indicator.
2. If the indicator is on, there is a short to ground in the Yellow/Black or Black/Yellow wires between the indicator and fuel filter assembly connector. If the indictor was off after No. 1, remove the cover assembly and perform water-in-fuel bench test. (Scheme 49) If bench test was not O.K., replace the "Drain Fuel Filter" module and re-test. If the bench test was O.K., fuel system is contaminated.
3. If "Drain Fuel Filter" indictor does not come on during bulb test, turn ignition "OFF" and disconnect the pigtail connector from the fuel filter assembly. Connect the female side to ground and turn ignition "ON". If indicator is on, replace the "Drain Fuel Filter" module and re-test. If indictor is off, check the bulb. If bulb is O.K., find and repair open in the Yellow/Black or Black/Yellow wires between the instrument panel and the fuel filter assembly connector.

Water-In-Fuel Detector Diagnosis (W/O NB9 Fuel Filter) 3/8" of detector probe must be in water. Scheme 48

NB9 Fuel Filter Assembly Bench Test Set-Up. Scheme 49

PURGING FUEL TANK

Water in the fuel tank may be removed with a pump or by siphoning. The pump or siphon hose should be hooked up to the 1/4" fuel return hose above the rear axle or under the hood near the fuel pump. Continue siphoning until all water is removed. Use clear plastic line or observe filter bowl on draining equipment to determine when clear fuel begins to flow. Remove the cap on fuel tank when purging the tank and replace cap when finished. Use the same precautions for handling diesel fuel that you would use for purging gasoline fuel tanks.

HPCA

1. When housing pressure is very low and adjusting the regulator See Adjusting the HPCA in this article, will not bring pressure to 9-11 psi (.6-.8 kg/cm 2 ), the HPCA pressure regulator ball is either not seated or partially seated or clogged because of a fault in the pressure regulator solenoid.
2. Remove the pressure regulator and attempt to blow air through it, pump side first, then outlet side. Replace if the check ball does not seat when blowing through the outlet side. If debris is found, check the injection pump.
3. To check the solenoid, connect the electrical leads to the HPCA solenoid. Turn the ignition to "RUN". The solenoid plunger should be up. Turn ignition to "OFF". Plunger should fall by itself or with a very light push. If solenoid fails these tests, replace or repair.

HPAA

1. Remove the HPAA solenoid and, using compressed air, blow through the assembly first from the pump side and then from the outlet side. Air should flow in both directions. Remove the pressure regulator from the solenoid and see if the plunger is free. If the assembly fails either test, replace it.
2. To test the solenoid, ground the housing using a jumper lead to the battery negative terminal. Attach another jumper lead to the same battery's positive post and connect this jumper to the solenoid lead terminal. The solenoid plunger should move inward with 12 volts applied and move fully back when jumper is disconnected.

Scheme 50

Scheme 51

1. Allow engine to warm up. Shut off engine. Remove air cleaner cover. Place MAP sensor with leads and vacuum hose attached aside. Remove air crossover and install covers. Disconnect HPAA solenoid lead and MVS harness.
2. Install MVS Test Harness (J-34678) and MVS Adapter Harness (J-64678-50) (Not needed on C series with internal EGR). Install tachometer. Start engine. Set parking brake and shift into "D". With alternator connected, set idle to 600 RPM (all V8), 675 (C Series with external EGR), 650 all others. (Scheme 50): C Series With Internal EGR Check MVS voltage as shown. (Scheme 51): Except C Series With Internal EGR Check MVS voltage as shown.
3. Set a multi-meter at the 20 volt scale and measure voltage between terminals "A" and "C". (Scheme 50)or (Scheme 51). This is V-Ref. Record this reading. Measure between terminals "B" and "C". This is the MVS voltage for the given engine load. Record this reading. Shift transmission to "P". Compare voltages recorded with the chart below. MVS Voltage Table V-Ref MVS Voltage 4.0.47-.49 4.1.48-.50 4.2.49-.51 4.3.50-.52 4.4.51-.54 4.5.53-.55 4.6.54-.56 4.7.55-.57 4.8.57-.59 4.9.58-.60 5.0.59-.61 5.1.60-.62 5.2.61-.63 5.3.63-.65 5.4.64-.66 5.5.65-.67
4. Shift into "D"and measure voltage between terminals "B" and "C" while throttle is moved quickly from idle to nearly full throttle. Voltage should go from less than 1 volt to over 4. If not, MVS must be adjusted. See Adjusting the MVS in this article.

INJECTION PUMP HOUSING PRESSURE TEST

1. Drain all fuel from pump. Connect an air line to the pump inlet connection. Air must be clean and dry. Seal off return line fitting. Completely immerse pump in bath of clean test oil.
2. Raise air pressure in pump to 20 psi (1.4 kg/cm 2 ). Leave pump immersed in oil for 10 minutes to allow trapped air to escape. It is normal for air to leak from the high pressure outlet fittings.
3. If pump is not leaking, reduce air pressure to 2 psi (.14 kg/cm 2 ) for 30 seconds. If there is still no leak, increase air pressure to 20 psi (1.4 kg/cm 2 ). If no leaks are present, pump is ready for use.

INJECTION PUMP HOUSING FUEL PRESSURE DIAGNOSIS

Connect pressure gauge; disconnect HPCA and HPAA leads. Shift into "PARK" and apply parking brake. Engine must be at operating temperature and at 1,000 RPM.

Pressure Greater Than 11 psi (.8 kg/cm 2 )

1. If pressure is above 11 psi (.8 kg/cm 2 ), check for restriction by disconnecting the return fuel line at the HPAA inlet. Install a hose over the pipe outlet with the other end of the hose in a container. Start engine. If housing pressure is 9-11 psi (.6-.8 kg/cm 2 ), either return pipes, hoses or tank unit are restricted.
2. If there is no change, adjust or clean housing pressure regulator and reset timing. Adjust pressure regulator to obtain 10 psi (.7 kg/cm 2 ). If pressure cannot be lowered to 9-11 psi, (.6-.8 kg/cm 2 ), remove pressure regulator and blow through it with compressed air, pump side first. Replace pressure regulator if faulty. If debris is found, remove injection pump cover to determine source. If pressure still cannot be lowered, repair pump.
3. If after checking for restriction in step 2), pressure is normal, check for restriction in return line or HPAA. Connect return line to the pump, disconnect return line from HPAA and run return flow into container. Reconnect the pump return pipe to the HPAA solenoid. Disconnect the return pipe (tank side) from the HPAA solenoid. Place a hose over the HPAA outlet. Direct other end into container and start engine.
4. If pressure is normal, there is a restriction in return lines, hoses or tank unit. If pressure is still high, the HPAA is faulty. See Testing and Adjusting sections in this article.

Pressure 5-9 psi (.3-.6 kg/cm 2 )

Adjust housing pressure regulator to 10 psi (.7 kg/cm 2 ) and reset timing. On V8 and V6 cars except C series, attempt to clean HPCA as shown in step 2) above. Also check the HPCA solenoid. See Testing HPCA in this article.

Pressure Less Than 5 psi (.3 kg/cm 2 )

If pressure is this low, debris in pump is keeping the housing pressure regulator check ball unseated. Attempt to blow out debris with compressed air. Also check the HPCA solenoid. See Testing HPCA in this article.

Pressure 9-11 psi (.6-.8 kg/cm 2 ) (C Series with Internal EGR)

1. Connect HPCA and HPAA leads. Check for 12 volts at Pink/White lead at altitude switch.
2. If voltage is 0 and pressure is 9-11 psi (.6-.8 kg/cm 2 ), pressure is normal. If pressure is more, there is an electrical problem in the HPCA and HPAA.
3. If voltage is 12 volts, pressure should be 13-17 psi (.9-1.2 kg/cm 2 ). If more, adjust HPAA pressure regulator. See Adjusting HPAA in this article. If less, check for 12 volts at HPAA lead. If less than 12 volts, there is an electrical fault of the HPAA. If more than 12 volts, the HPAA is faulty. See Testing and Adjusting sections in this article.

Pressure 9-11 psi (.6-.8 kg/cm 2 ) (V8 and V6 Except C Series with Internal EGR)

1. For all tests below, connect HPCA and HPAA leads. Disconnect MAP sensor harness connector.
2. If pressure drops to 3-5 psi (.2-.3 kg/cm 2 ) (C Series) or 6-8 psi (.4-.56 kg/cm 2 ) (except C Series), pressure is normal. If pressure is under 3 psi (.2 kg/cm 2 ) or over 5 psi (.3 kg/cm 2 ) (C series) or under 6 psi (.4 kg/cm 2 ) or over 8 psi (.56 kg/cm 2 ) (except C Series), disconnect the HPAA lead. If pressure drops, adjust the HPAA pressure regulator. If there is no change in pressure, the HPAA is faulty. See Testing and Adjusting sections in this article.
3. If there was no change in pressure after step 1), the HPCA and HPAA are malfunctioning. See Testing and Adjusting and sections in this article. If the pressure rose, there is a malfunction of the HPCA or HPAA. Disconnect the HPAA lead. If pressure is 9-11 psi (.6-.8 kg/cm 2 ) the HPCA is malfunctioning. If the pressure is 0, the HPAA is malfunctioning and should be adjusted.

EGR

Proper EGR solenoid resistance is between 20-40 ohms. The solenoid operates on 12 volts, supplied by the ignition. The ground is completed by the ECM (Electronic Control Module) to turn the solenoid "ON", allowing vacuum to the EGR. The signal from the ECM is Pulse Width Modulated, which changes "ON" time from 0 to 100%.

HPCA TEMPERATURE SWITCH

The temperature switch is calibrated to open the HPCA circuit at about 125°F (52°C). Replace switch if defective.

Scheme 52

1. Check the tightness of the fuel inlet fitting to injector nozzle body. Fitting should be tightened to 35 ft. lbs. (47 N.m).
2. Remove injection nozzles. See Removal & Installation in this article. Clean carbon from tip of nozzle with a soft brass brush.
3. Assemble injector to Diesel Injection Nozzle Tester (J-29075). Use a connecting line (high pressure) 12" long by 1/4" O.D. by 1/16" I.D. between injector and tester.
4. Refer to test equipment manufacturer's instructions for exact tester operating instructions. Use SAE J967D calibrating oil at room temperature to test injectors. WARNING: DO NOT use diesel fuel. It is unstable with respect to corrosion inhibition and may cause skin problems. When testing injectors, keep spray contained to avoid serious injury. Pressure of atomized test spray has sufficient penetrating power to puncture flesh.
5. When testing opening pressure, handle of tester should be operated at a rate of 3 to 6 seconds for a full stroke. Minimum opening pressure for new nozzles on V8 models (Blue color band) is 1000 psi (70 kg/cm 2 ).
6. Opening pressure for V6 models (Red color band) is 800 psi (56 kg/cm 2 ). Opening pressure is about 150 psi (10.5 kg/cm 2 ) less for all used nozzles.
7. When testing injector nozzle spray pattern, close pressure gauge and operate tester handle at a rate of 2 seconds per stroke. Fuel should be atomized at tip. There should not be a solid column of fuel or droplets formed.
8. Note spray pattern and compare with examples shown. (Scheme 52) If incorrect, replace injector. (Scheme 52): Injector Nozzle Spray Patterns Keep spray contained to prevent injury to any body part.
9. To test injector nozzle seat for leakage, decrease pressure to at least 290 psi (20.3 kg/cm 2 ) BELOW actual opening pressure. Dry nozzle tip with compressed air.
10. Increase pressure to 150 psi (10 kg/cm 2 ) BELOW actual opening pressure. Maintain pressure for 5 seconds. Compare fuel leakage to examples shown. (Scheme 53)
11. Replace defective injectors. Install carefully and tighten to specifications.

Checking Injector Nozzle Seat Tightness. Scheme 53

REMOVAL & INSTALLATION

FUEL SYSTEM BLEEDING

1. When changing fuel filter, injection pump, or when vehicle has run out of fuel, it may be necessary to purge air from injection pump. Air may be purged and cranking time reduced by activating the HCPA system.
2. Unplug electrical connector from the engine temperature sensor/switch on engine block. Connect jumper wire across terminals. After engine is running, remove jumper wire and connect temperature switch to harness.

Scheme 54

Scheme 55

1. Pump cover, guide stud, and throttle shaft seals may be replaced with injection pump on vehicle. Remove air cleaner and crossover. Install screens over air intakes. Disconnect fuel return line and wiring from injection pump.
2. Clean injection pump cover and area around throttle rod and guide stud. Place rags in engine valley to catch fuel. Scribe a line on vacuum regulator valve and pump body so valve can be reinstalled without resetting.
3. Remove vacuum regulator valve. Remove throttle and T.V./detent cable (V6), throttle rod (V8), and return springs. Remove throttle cable bracket (V8).
4. Install Aligner (J-29601) over throttle shaft with slots of tool engaging pin. Put spring clip of Aligner (J-29601) over throttle shaft advance cam and tighten wing nut. (Scheme 54)
5. Without loosening wing nut, pull Aligner (J-29601) off shaft. This provides a reference for proper alignment during reassembly.
6. Drive pin from throttle shaft. Loosen clamp screw and remove advance cam and fiber washer. Remove any burrs that may have been caused by pin removal. CAUTION: DO NOT allow any dirt or foreign objects to drop into injection pump. Engine damage will result. (Scheme 54): Roosa-Master Injection Pump With Advance Cam Tool Installed
7. Remove injection pump cover and remove screws from cover. Note position of metering valve spring over top of guide stud. This position must be exactly duplicated during reassembly.
8. Remove guide stud and washer, noting position for reassembly. Rotate min-max governor assembly up and remove from throttle shaft.
9. Remove throttle shaft and inspect. It may be necessary to loosen and rotate pump slightly to remove throttle shaft.
10. If damaged or worn, replace throttle shaft. Inspect shaft bushings. If replacement of shaft or bushings is necessary, pump must be sent to authorized repair dealer. (Scheme 55): Roosa-Master Injection Pump With Cover Removed
11. Remove throttle shaft seals. DO NOT cut off, as a nick on shaft will cause leakage. Coat new seals lightly with grease and install on shaft.

Installation

1. Slide shaft into pump until min-max governor will slip onto throttle shaft. Rotate governor downward, hold in position, and slide throttle shaft and governor into place.
2. Install new mylar washer, throttle shaft advance cam ( DO NOT tighten screw), and new throttle shaft drive pin. Realign advance cam in original position with Aligner (J-29601).
3. Place a .005" (.13 mm) feeler gauge between white washer and pump housing (side opposite advance cam). Tighten cam screw and apply Loctite 290 .
4. Install guide stud with new washer. Ensure that metering valve spring extension rides on top of guide stud. Tighten guide stud to 85 INCH Lbs. (10 N.m). Overtightening of guide stud will strip aluminum threads in housing.
5. Hold throttle in idle position and install new pump cover seal. DO NOT insert screws in cover. Position cover slightly forward and above pump. Carefully move cover rearward and downward into position. DO NOT damage seal.
6. Insert screws. Use flat and lock washers with flat washers against pump cover. Tighten screws to 33 INCH Lbs. (4 N.m). Install vacuum regulator valve, aligning marks made during removal.
7. Connect battery ground cables, turn ignition switch to "RUN" position. Touch Pink solenoid wire to solenoid terminal. A clicking sound should be heard as solenoid operates. If not, remove cover and check solenoid operation. CAUTION: If clicking sound is not heard as solenoid wire is connected, DO NOT start engine. Throttle may be stuck in wide-open position.
8. If solenoid clicks, connect all wires to pump housing. Reconnect throttle cable and T.V./detent cable (V6), throttle cable bracket and throttle rod (V8), and throttle return springs.
9. Install fuel return line. Start engine and check for leaks. Allow engine to idle for several minutes to purge air and smooth out idle. It may be necessary to stop engine for several minutes to allow air to rise and be purged. Check and adjust the MVS voltage. See Adjustments in this article. Remove intake manifold screens. Reinstall air crossover and air cleaner.

INJECTION PUMP SEALS (OFF-VEHICLE SERVICE)

Timing cover, auto advance, hydraulic head, and drive shaft seal replacement require removal of injection pump from vehicle. See Removal & Installation in this article. Whenever seals are replaced, injection pump must be pressure tested. See Injection Pump Housing Pressure Test in this article.

Scheme 56

Scheme 57

1. Remove injection pump. Mount on holding fixture. DO NOT clamp injection pump flange in vise. Remove timing cover retaining screws. Lift off cover and gasket. (Scheme 56) (Scheme 56): Injection Pump Housing & Drive Group
2. Tap the advance pin hole plug lightly with a hammer to loosen. Remove plug and advance pin. Discard seal. (Scheme 57)
3. Remove advance cam actuating arm. Remove spring side advance piston hole plug. Remove plug, piston, spring, and slide washer. Remove power side advance piston hole plug.
4. Remove plug, piston, and slide washer. Disassemble both plugs and pistons. Remove lip seal from spring side plug. (Scheme 57) (Scheme 57): Injection Pump Automatic Advance Group
5. Remove drive shaft by pulling it out of pump with a twisting motion. Remove drive shaft seals from pump.
6. To remove hydraulic head seal, remove throttle shaft and seals and metering valve. See Injection Pump Seals (On Vehicle Service). Remove housing vent screw assembly, advance pin and hole plug.
7. Position pump assembly so that rear of pump is sloping down. Remove locating head screw and seal. Using a twisting motion, remove hydraulic head assembly. Remove "O" ring seal.

Replace all seals and "O" rings. To assemble, reverse disassembly procedure and note the following: Tighten advance pin hole plug to 75-100 INCH Lbs. (8.5-11.3 N.m). Tighten head locating and locking screws to 15-18 ft. lbs. (20-25 N.m).

Removal

Remove air cleaner, then remove filters and pipes from air crossover. Remove bolts and washers and lift crossover from manifold. Place screened covers over intake manifold openings.

To install, reverse removal procedure, noting the following: Tighten air crossover bolts to 24 ft. lbs. (33 N.m) on V6 models or 22 ft. lbs. (30 N.m) on V8 models. Install new gaskets between crossover and intake manifold.

1. Remove air cleaner and crossover. Install screened covers over openings in intake manifold. It is not necessary to remove pump to replace a line(s). NOTE: In some cases, it may be necessary to disconnect the intermediate steering shaft. See Removing and Installing Injectors in this article.
2. Remove injection pump line clamps. It is not necessary to use a back-up wrench when removing lines from pump.
3. Remove injection pump lines. Cap open lines, injectors, and pump fittings. Using a back-up wrench on upper injector nozzle hex, disconnect injection pump lines at injector inlet fittings.

1. If several lines are to be replaced, start by connecting lower lines first. Install new injection pump line(s) loosely. Position line properly. Tighten all high pressure fuel lines to 25 ft. lbs. (34 N.m).
2. Use a back-up wrench when tightening fuel lines to fuel inlet fittings on injector nozzles. Install line clamps. Start engine and check for fuel leaks. Remove screened covers and install air crossover and air filter assembly.

1. Remove air cleaner. Remove crankcase ventilation filter and pipes from valve covers. Remove air crossover and install intake manifold screened covers.
2. On V6 engine, remove fuel lines and fuel pump. Disconnect throttle cable, T.V. cable, and throttle return spring.
3. On V8 engine, disconnect the throttle rod and return spring. If equipped with A/C, disconnect the rear compressor brace. On V8 remove Crankcase Depression Regulator Valve and fuel filter.
4. On all models, disconnect fuel return line at injection pump. Disconnect injection line clamps. Disconnect injection lines from pump. Cap all open lines. Remove pump retaining bolts/nuts.
5. Remove injection pump. Discard pump-to-adapter "O" ring. Remove MVS if pump is to be sent to authorized repair dealer.

Scheme 58

Scheme 59

1. Install MVS with new "O" ring. Apply Loctite 242 to MVS threads. Tighten to 30 INCH Lbs. (3.5 N.m).
2. Position No. 1 cylinder at TDC compression stroke by aligning mark on balancer with zero mark on engine. Align offset tang on pump driveshaft with pump driven gear. On V8, offset is to the right. (Scheme 58) On V6, offset is down. (Scheme 59) (Scheme 58): V8 Pump Driven Gear Offset at TDC Figure shows intake manifold removed. (Scheme 59): V6 Pump Driven Gear Offset at TDC Figure shows intake manifold removed.
3. Install new pump-to-flange assembly "O" ring. Install pump and fully seat by hand. If new flange assembly is installed, set injection pump at center of slots in pump mounting flange.
4. If original flange assembly is being used, align pump timing mark with mark on flange assembly. Install retaining bolts/nuts and washers.
5. Tighten nuts (V8) to 18 ft. lbs. (24 N.m). Tighten bolts (V6) to 37 ft. lbs. (51 N.m). Connect injection lines to pump. Install injection line clamps. Connect fuel return line.
6. On V8 engine, install fuel filter, Crankcase Depression Regulator Valve, and rear A/C compressor brace. On all models, install throttle and T.V. cables into intake manifold.
7. On V6 engine, connect throttle cable and T.V. cable to pump throttle lever. Connect throttle return spring. Adjust T.V. cable. See Adjustments in this article.
8. On V8 engine, connect throttle rod and return spring. Adjust throttle linkage. See Adjustments in this article.
9. Start engine and check for leaks. Check and if necessary, reset pump timing. See Adjustments in this article.
10. Adjust vacuum regulator valve if its original position is disturbed or a replacement pump has been installed. See Adjustments in this article.
11. Remove screened covers and install air crossover. Install tubes and hoses in air crossover. Reset idle speed. See appropriate article in TUNE-UP Section. Install air cleaner and EGR valve hose.

Remove injection pump as previously described. On V6 engine, remove intermediate adapter. On V8 engine, loosen adapter bolts. Pry out adapter seal.

1. Apply chassis lube to seal. Place seal on Installer (J-28425). (Scheme 60) Install seal on pump adapter.
2. Tighten adapter bolts to 25 ft. lbs. (34 N.m). Tighten intermediate adapter bolts to 35 ft. lbs. (47 N.m). Install injection pump.

Installing Adapter Seal V8 is illustrated. V6 is similar. Scheme 60

INJECTORS

Note. When working on right (rear) bank of a transverse-mounted V6 engine, intermediate steering shaft must be disconnected from steering gear stub shaft.

1. On transverse-mounted V6 engines (front wheel drive), it may be necessary to perform the following procedure in order to remove injectors.
2. Rotate intermediate steering shaft so steering gear stub shaft clamp bolt is accessible. Remove clamp bolt. Disconnect intermediate shaft from stub shaft.
3. Remove engine-to-body support strut. Place floor jack under front crossmember of the cradle. Raise jack until jack just starts to raise vehicle.
4. Remove the 2 front engine cradle-to-body mount bolts with lower cushions and back-up washers. Remove cushions from bolts.
5. Thread body mount bolts with back-up washers a minimum of 3 threads into cage nuts so that bolts restrain cradle movement. Release floor jack slowly until crossmember contacts body mount bolt retainers.
6. On V8 engine, disconnect fuel line from injector. Use back-up wrench on upper injector hex. Cap injector and lines. Remove injector. Remove copper nozzle gasket from cylinder head if gasket did not remain on injector.

On V6 engines with aluminum cylinder heads, apply Lubricant (1052771) on injector threads before installation. On V6 and V8 engines, tighten injectors to 35 ft. lbs. (34 N.m). Reverse removal procedure to complete installation.

1. To remove glow plugs on right side of transverse-mounted V6 engine, it may be necessary to use same removal procedure as injectors.
2. On all engines, unplug electrical connector from glow plug and remove plug with deep socket. On V6 engine with aluminum cylinder heads, apply Lubricant (1052771) to glow plug threads.
3. Tighten glow plugs to 15 ft. lbs. (21 N.m) on V6 or 12 ft. lbs. (16 N.m) on V8.

INJECTION TIMING

Note. For optimum engine performance, timing adjustments must be made using Timing Meter (J-33075). Engine malfunctions must be corrected before timing adjustments are made.

Checking

1. Engine must be at normal operating temperature. Place transmission selector lever in "P". Remove air cleaner and install Cover (J-26996-1). Remove MAP sensor retainer. Disconnect EGR valve hose.
2. Clean engine probe holder (RPM counter) and crankshaft balancer rim. Clean lens on both sides of glow plug probe. Clean lens in the photo-electric pick-up.
3. Use a dull toothpick to scrape the carbon from the combustion chamber side of glow plug probe. Retarded readings will result if probe is not clean.
4. Install RPM probe into crankshaft RPM counter (probe holder). Remove glow plug from No. 3 cylinder on a V8 or No. 1 on a V6. Install glow plug probe in glow plug opening. Tighten probe to 8 ft. lbs. (11 N.m).
5. On V8 engine, set timing meter offset selector to B (99.5). On V6 engine, set selector to A (20). Connect battery leads. Unplug alternator 2-lead connector.
6. If alternator lead is difficult to remove, remove gauge fuse when engine is not running. Start engine. Check injection timing. See Injection Pump Timing Specifications.

INJECTION PUMP TIMING SPECIFICATIONS

Adjusting

1. Shut off engine. Note relative position of marks on pump flange and pump adapter. Loosen nuts or bolts retaining pump to the adapter. Rotate pump to left to advance timing and to right to retard timing. Width of mark on intermediate adapter is about 2/3°. Adjust timing. Tighten bolts to 35 ft. lbs. (47 N.m).
2. Start engine and recheck timing. Reset timing if necessary. Adjust throttle linkage assembly on V8 engine. On V8 and V6 engines, reset fast and curb idle speeds. See appropriate article in TUNE-UP Section. NOTE: Wild needle fluctuations on timing meter indicate a cylinder that is not firing properly. Condition must be corrected prior to adjusting timing.
3. If after resetting timing, timing marks are far apart and engine does not perform correctly, dynamic timing still could be incorrect. A malfunctioning cylinder can cause incorrect timing.
4. If so, check timing on alternate cylinder. Timing can be checked on cylinders No. 2 or No. 3 on V8 engine, or No. 1 or 4 on a V6 engine. If timing difference exists between cylinders, try both positions to determine which timing works best.

Scheme 61

Scheme 62

1. Check pump timing. Adjust if necessary. Disconnect T.V. (or detent) cable from throttle assembly. Disconnect cruise control servo rod, if equipped.
2. Loosen lock nut on pump rod and shorten several turns. Rotate bellcrank assembly to full throttle position and hold. Lengthen pump rod until injection pump lever just contacts full throttle stop.
3. Release bellcrank assembly. Tighten pump rod lock nut. Depress and hold metal lock tab on T.V. cable upper end. Move slider through fitting in direction away from bellcrank assembly until slider stops against metal fitting. (Scheme 61): Exploded View of V8 Throttle Linkage (Scheme 62): Adjusting T.V. or Detent Cable
4. Release metal tab. Install cruise control servo rod. Connect T.V. cable. Rotate bellcrank lever assembly to full throttle stop and release lever assembly.
5. Adjust vacuum regulator valve. Adjust idle speed. See appropriate article in TUNE-UP Section.

Scheme 63

1. Remove air crossover. Install screened covers in intake manifold openings. On V8 engine, disconnect throttle rod from pump. On V6 engine, disconnect throttle cable and T.V. cable from pump throttle lever.
2. Loosen vacuum regulator valve-to-injection pump bolts. Install carburetor Angle Gauge Adapter (BT-7944 or J-26701-15) to the injection pump throttle lever.
3. Place Angle Gauge (BT-7704 or J-26701) on adapter. Rotate throttle lever to wide open throttle position. Set angle gauge to 0°. Center bubble in level. (Scheme 63) (Scheme 63): Adjusting Vacuum Regulator Valve
4. Set angle gauge to 58° on V8 engine, and 49° on V6 engine. Rotate throttle lever so lever bubble is centered. Attach vacuum pump to port "A". Install vacuum gauge to port "B". (Scheme 64)
5. Apply 22 in. Hg of vacuum to port "A". Rotate vacuum valve clockwise to obtain 10.6 in. Hg on automatic transmission, and 8.9 in. Hg on manual transmission.
6. Tighten bolts and remove vacuum gauge, pump, and angle gauge. Connect throttle and T.V./detent cables (V6) or throttle rod (V8). Remove screened covers. Install air crossover.

Vacuum Regulator Valve Locations. Scheme 64

For Except C Series with Internal EGR

1. Install the HPAA solenoid assembly. Disconnect the electrical harness connector from the MAP sensor, thus activating the HPCA, HPAA and AFL solenoids even if the car is below 4,000 ft. Start the engine. Housing pressure should be 3-5 psi (.2-.3 kg/cm 2 ) for C series and 6-8 (.4-.56 kg/cm 2 ) for others.
2. If not within specifications, adjust the HPAA. Disconnect the electrical harness. Remove the HPAA assembly and the line fitting from the pressure regulator. Rotate the adjustment screw with a 1/8" hex wrench. Rotating screw one turn clockwise will increase housing pressure by 3.2 psi (.22 kg/cm 2 ).

C Series with Internal EGR

1. Install the HPAA assembly onto the fuel return pipes. Connect a jumper lead to the positive terminal of the battery and connect the jumper to the HPAA solenoid lead terminal. With engine running, housing pressure should be 13-17 psi. (.9-1.2 kg/cm 2 ).
2. If not to specifications, disconnect the jumper to the HPAA. If housing pressure is not 9-11 psi (.6-.8 kg/cm 2 ), adjust the housing pressure regulator. Reconnect the jumper to the HPAA. If housing pressure is not 13-17 psi (.9-1.2 kg/cm 2 ), adjust the HPAA pressure regulator. See No. 2 above.

ADJUSTING THE HPCA

To adjust the HPCA pressure regulator, see step 2) under Adjusting the HPAA (Except C Series with internal EGR) in this article.

ADJUSTING THE MVS

1. Shut off engine and remove MVS adjusting hole plug. DO NOT move the MVS assembly. Turn the adjustment screw in 1/8 turn increments. Reinstall the adjusting hole plug and perform the voltage tests. See MVS Testing in this article.
2. If voltage is not to specifications, readjust the MVS as needed. Use a new "O" ring seal on final installation of MVS plug and tighten to 30 INCH Lbs. (3.5 N.m). Reconnect electrical connections, start engine, check for fuel leaks and install air crossover and air cleaner assembly.

Scheme 65

1. Remove injectors from engine. Remove and discard copper sealing washer from tip of injector using a pair of diagonal cutters. DO NOT damage nozzle tip. Remove all loose dirt and carbon. CAUTION: Parts of each nozzle assembly are preset and calibrated to meet certain specifications. DO NOT mix up nozzle components.
2. Unscrew inlet fitting from body. Press nozzle tip assembly out of body. DO NOT damage nozzle tip. (Scheme 65) (Scheme 65): Exploded View of Injection Nozzle
3. Slide retainer sideways to release retainer from valve. Remove spring seat and spring. Press valve from spray tip.

Cleaning & Inspection

1. Clean all disassembled pieces in Sonic Bath Cleaner (BT-8041 or J-29653). If sonic bath cleaner is used, parts are clean when carbon is removed from tip of valve.
2. Inspect all components for excessive wear or damage. Tip of valve must be completely free of contamination.

Reassembly

1. Insert valve into spray tip. Install spring, spring seat, and retainer. Using a clean, unpainted piece of steel as a base, compress spring.
2. Push on retainer and slide to a center position after spring has been compressed. After assembly, rotate retainer to assure proper seating of components. Install nozzle tip into body.
3. Insert inlet fitting into body. Tighten to 35 ft. lbs. (47 N.m). Test injector. See Testing in this article.
4. Install new copper washer before assembling into engine. It may be necessary to crimp washer slightly to create an interference fit so it will remain in place.

SPECIFICATIONS

Note. Specifications not available. Refer to specifications within appropriate REMOVAL & INSTALLATION , TESTING or ADJUSTMENTS subject in this article.

Cutlass Supreme, Delta 88/Custom Cruiser & Toronado 5.7L V8 Glow Plug System Wiring Diagram. Scheme 66

All Cadillac, Oldsmobile 4.3L V6 Cutlass Cierra, Chevrolet 5.7L V8 Impala & Caprice 8 glow plugs shown. V6 models use only 6 glow plugs. Scheme 67

See also:
• REMOVAL & INSTALLATION
• TESTING