Fuel Injection System - Diesel Jeep Wagoneer XJ

COMPONENT TESTING

Note. Specific component testing information not available. Refer to any tests performed during TROUBLE SHOOTING or TESTING procedures.

DESCRIPTION

A Bosch VE4, single piston, high pressure rotary pump is used to inject a precisely metered amount of fuel into each cylinder at precise intervals. The pump is mounted on left side of engine, and provides correct amount of timing advance for various operating conditions.

High pressure fuel lines carry fuel from pump to an injector at each pre-combustion chamber. All lines are of equal length to ensure that there is no variance in timing. Any excess fuel in supply system is returned to tank by a fuel return system.

A reference pressure regulator is attached to firewall (above engine). This regulator automatically compensates for altitude changes.

An electrical glow plug system is used to assist engine starting and cold engine operation. A glow plug is located in pre-combustion chamber for each cylinder. Glow plug current is controlled by a timer.

Scheme 43

COLD START SYSTEM

The cold start system consists of a capsule (spring housing), linkage, thermostat and a bi-metallic spring. When engine is cold, thermostat inside capsule releases bi-metallic spring. The spring pulls timing control lever toward "ADVANCE" position, and throttle lever is pulled toward fast idle.

As engine temperature increases, thermostat slowly expands, compressing spring. When spring is compressed, control cable is released, and throttle lever returns to original position.

FUEL INJECTION PUMP

The Bosch VE4 mechanical injection pump contains a low pressure vane-type transfer pump and a high pressure distributor-type injection pump.

The transfer pump output pressure (injection pump housing pressure) averages 50-100 psi (3.5-7.0 kg/cm 2 ) depending upon engine speed. The plunger injection pump boosts fuel pressure to about 2000 psi (140 kg/cm 2 ). Pump assembly is also equipped with an electric fuel shutoff solenoid.

INJECTORS

The injectors spray fuel into a pre-combustion chamber as each compression stroke occurs. Each injector receives a high pressure pulse of fuel which forces open needle valve allowing fuel to pass into chamber.

FUEL FILTER

An in-line fuel filter is attached to firewall near power brake unit. This assembly removes water and contaminants from incoming fuel supply. This filter also heats fuel when ambient temperature falls below 46°F (8°C).

FUEL SUPPLY SYSTEM

Diesel fuel is drawn through a water separator from fuel tank by an engine mounted mechanical fuel pump. This pump is driven by an eccentric cam mounted on crankshaft and puts out about 3 psi (.21 kg/cm 2 ) to injection pump. A small screen type filter is located in fuel tank at pick-up. After leaving filter, diesel fuel enters pump through center inlet fitting. A fuel return line is provided to return excess fuel to tank.

FUEL INJECTION LINES

A high pressure fuel injection line is routed from injection pump to each injector. Injection lines are of equal length but are formed differently, to prevent timing difference from cylinder-to-cylinder, and ease installation. Lines are pre-formed by manufacturer, and are not interchangeable.

GLOW PLUG SYSTEM

Engine starting is aided by an electric glow plug system. Glow plugs are small heaters that assist in cold starting. A glow plug is threaded into each cylinder combustion chamber. This system pre-heats each combustion chamber to aid ignition of fuel.

System consists of 4 glow plugs, control switch, timer, and a wiring harness which incorporates 4 fused wires (one for each glow plug) located between wiring harness and glow plug terminal.

The glow plug controller and relay cycle 12 volts to these 6-volt heaters, which causes them to heat rapidly. After engine starts, glow plugs remain on between 4 and 10 seconds during initial starting cycle.

Before suspecting fuel injection system as source of engine trouble, other engine systems should be checked. Ensure that air intake and exhaust systems are not restricted, and that fuel supply system provides an adequate amount of clean fuel to injection pump. If a problem still exists after checking these systems

1. Check fuel lines to injectors for kinks or restrictions. Replace as necessary. Run engine at RPM where problem was most pronounced.
2. Momentarily loosen fuel line, 1/2 to 1 turn, on one injector. Then tighten fuel line. Repeat for each cylinder.
3. If there is no difference in engine operation when a fuel line is loosened, that injector should be removed and tested.

Scheme 44

1. Remove injectors from engine. Check injectors for erosion (due to unfiltered air particles), carbon build-up, or Blue-colored tip (caused by excessive engine heat). Replace any damaged injectors as necessary.
2. Fill reservoir of Bosch Nozzle Pressure Tester (EFEP60H) with clean test oil. Connect injector and holder assembly to tester. Close pressure gauge valve. Quickly operate tester lever 8-10 times to bleed air from tester. CAUTION: DO NOT allow test oil to be sprayed onto hands or fingers while testing. High pressure from nozzle spray can penetrate skin, which could cause blood poisoning.
3. Open pressure gauge valve 1/4 turn. Slowly operate tester (one pump/second), noting pressure required to open nozzle. Nozzle opening pressure should be 1885-2001 psi (133-141 kg/cm 2 ). Injectors with incorrect opening pressure should be replaced.
4. Slowly operate tester and note spray pattern of each injector. Spray should emerge at a straight angle, and should have an even, finely atomized pattern. Replace any injectors that do not have correct spray pattern. A "whistling" sound, produced during testing, is a normal condition.
5. Slowly operate tester until pressure reading is 290 psi (20 kg/cm 2 ) below normal opening pressure. Hold pressure at that point for 10 seconds. No fuel should drip from nozzle. If leakage occurs during 10 second period, replace injector. A slight wetting of nozzle tip is normal.

REFERENCE PRESSURE REGULATOR

Install "T" fitting at connection "A". (Scheme 45) Connect a vacuum gauge to "T" fitting. Start and run engine at idle. Note vacuum reading. Compare reading with specification, and replace pressure regulator if vacuum reading is incorrect. See ALTITUDE COMPENSATED VACUUM table.

Testing Reference Pressure Regulator Install vacuum gauge "T" fitting at connection "A". Courtesy of American Motors/Jeep Corp. Scheme 45

ALTITUDE COMPENSATED VACUUM

Glow Plug Diagnosis - TEST A. Scheme 46

Glow Plug Diagnosis - TEST B. Scheme 47

Glow Plug Diagnosis - TEST C. Scheme 48

Glow Plug Diagnosis - TEST D. Scheme 49

TURBO BOOST CUT-OUT SWITCH

1. Disconnect hose from test point "A". (Scheme 50) Connect a pressure gauge to hose. Start and run engine at 3000 RPM. Record pressure reading. Disconnect gauge and reconnect hose. NOTE: If no pressure is indicated, check turbocharger operation, and for a pinched hose between manifold and turbo boost cut-out switch.
2. Disconnect hose from test point "B". (Scheme 50) Connect a pressure gauge to hose. Start and run engine at 3000 RPM. Record pressure reading. Pressure reading should be equal to reading at test point "A" in step 1.
3. If pressure is okay, turbo boost cut-out switch is operating correctly. If pressure is not okay, and engine coolant temperature is below 239°F (115°C), replace cut-out switch. Disconnect gauge and reconnect hose.

Scheme 50

FUEL SHUTOFF SOLENOID

1. If engine will not start, test for correct supply voltage at fuel shutoff solenoid wire harness connector with ignition on. Voltmeter reading should be at least 8 volts.
2. If voltage is correct, remove fuel shutoff solenoid from injection pump. Connect a jumper wire between battery positive terminal and fuel shutoff solenoid connector terminal.
3. Connect another jumper wire to battery negative terminal and gently contact shutoff solenoid housing. Solenoid should click. Replace solenoid if necessary.

COLD START THERMOSTAT CAPSULE

Removal

1. Clamp and remove coolant lines from cold start capsule. Remove one capsule retaining bolt. Replace it with a threaded rod (6mm dia. x 70 mm long).
2. Install and tighten nut onto threaded rod. Remove other capsule retaining bolt. Replace it with a duplicate threaded rod. Install and tighten nut onto second threaded rod.
3. Alternately loosen the 2 nuts. After tension is released remove nuts completely. Separate rear capsule housing from bracket. Remove retaining nut, thermostat capsule and "O" ring from housing.

Installation

Ensure components are in position. (Scheme 51) To complete installation, reverse removal procedure.

Exploded View of Cold Start Capsule To avoid injury, follow removal procedures precisely. Courtesy of American Motors/Jeep Corp. Scheme 51

Scheme 52

1. Disconnect battery negative cable. Clamp cold start thermostat capsule coolant hoses. Remove capsule coolant hoses from capsule. Disconnect throttle cable and fuel shutoff solenoid connector.
2. Disconnect automatic transmission throttle cable and cruise control cable (if equipped). Disconnect and plug fuel delivery and return lines. Remove alternator and power steering drive belts. Remove timing belt cover.
3. Rotate crankshaft until No. 1 piston is at TDC position. Ensure that sprocket timing mark is aligned with center of boss on cylinder head cover, and that injection pump sprocket timing mark is aligned with center of injection pump boss. (Scheme 52)
4. Position Holding Plate (Mot. 854) between camshaft and injection pump sprockets. (Scheme 52) It may be necessary to turn crankshaft back-and-forth slightly, to position holding plate correctly.
5. Loosen sprocket retaining nut. Turn nut out until it reaches beginning of threads. Attach puller to sprocket. Disconnect and plug fuel pipe fittings from injectors.
6. Remove fuel pipes. Remove injection pump rear attaching bolts. Remove plastic shield from underneath injection pump. Remove 3 retaining nuts at front of pump. NOTE: It may be necessary to remove the alternator, to gain access to lower front injection pump retaining nut.
7. Separate injection pump from sprocket bolts using puller. Remove separator and sprocket retaining nut. DO NOT remove sprocket. Sprocket holding plate and timing belt will hold sprocket in place to ease installation.
8. Remove injection pump from mounting bracket. Remove key from injection pump drive shaft.

Scheme 53

Scheme 54

Scheme 55

1. Remove screw plug and copper washer from center of 4 high pressure outlets on rear of injection pump. (Scheme 53) Install Dial Indicator Support (Mot. 856) in place of screw plug. Insert dial indicator into support. (Scheme 53)
2. Position nut and lock nut on end of injection pump drive shaft. Lock the 2 nuts together. Loosen cold start throttle cable set screw. Move levers back slightly and rotate clevis pin 1/4 turn to disengage cold start system. (Scheme 54)
3. Rotate injection pump until piston is at BDC position (Dial indicator will stop moving at this point). Zero dial indicator. NOTE: With injection pump piston at BDC position, the pump shaft keyway should be positioned just before centerline of No. 1 fuel outlet fitting.
4. Remove nut and lock nut from pump drive shaft. Insert key in pump shaft keyway. Install injection pump, leaving dial indicator in place. Ensure drive shaft key is aligned with keyway in sprocket. Loosely install pump retaining nuts.
5. Install sprocket washer and retaining nut onto pump shaft. Tighten sprocket retaining nut. Remove sprocket holding plate. Rotate crankshaft 3 revolutions. Check timing belt tension. Adjust if necessary.
6. Remove screw plug from TDC access hole in cylinder block, and install TDC Rod (Mot. 861). (Scheme 55) Slowly rotate crankshaft clockwise, until TDC rod can be inserted into TDC hole in crankshaft counterweight.
7. With TDC rod in hole, dial indicator should read.031-.033 in. (.79-.84 mm). This reading represents the amount of pump piston lift. If reading is correct, go to step 10. If reading is incorrect, go to next step.
8. To increase piston lift, rotate pump toward engine, and then slowly rotate pump away from engine until correct reading is obtained. To decrease piston lift, slowly rotate pump away from engine until correct reading is obtained.
9. Remove TDC rod. Slowly rotate crankshaft clockwise 2 complete revolutions, and insert TDC rod in TDC hole in crankshaft counterweight. Dial indicator should read.031-.033 in. (.79-.84 mm). If reading is incorrect, repeat steps 8 and 9. If reading is correct, go to next step.
10. Remove TDC rod from hole, and install screw plug. Remove dial indicator and support. Install copper washer and screw plug. Reconnect fuel pipes. Compress timing control lever and install clevis pin.
11. Hold lever against clevis, and tighten set screw. Install and tighten injection pump rear bracket nuts. To complete installation, reverse removal procedure. The fuel return banjo nut is matched and calibrated to pump. If a new pump is installed, a new matched banjo nut must be used.

Note. DO NOT reverse the 2 fuel line banjo nuts. The delivery line nut has two .1575" (4.0 mm) diameter holes, and the return line nut has a calibrated orifice.

1. Before removing injectors, clean injector surrounding area and pipe connections with clean fuel or solvent to prevent contamination. Blow area dry with compressed air. Remove fuel return hose fitting and washer.
2. Remove high pressure fuel line fitting from injector. Remove injector clamp retaining nuts and washers. Remove injector clamp and injector. Remove copper seal and heat shield.

1. Clean injector bore in cylinder head thoroughly. Remove protective cap from injector tip. Coat injector threads with anti-seize compound.
2. Install a new copper gasket on injector, using a small amount of grease to retain gasket. To complete installation, reverse removal procedure. Use a new heat shield and copper seal.

Removal & Installation

1. Attach a long piece of tubing to draincock outlet. Place end of drain hose into drain pan. Open filter assembly vent valve (Black cross-shaped knob) and draincock. Fully drain fuel filter assembly.
2. Open center filter bail wire, and then top clip. Open bottom clip and remove fuel filter. Hold filter upright to avoid spilling remaining fuel. Dispose filter in a safe manner to avoid fire hazard.
3. Install new filter and clip securely into place. Close draincock and vent valve. Start engine and check for leaks.

Scheme 56

1. Start and warm engine to normal operating temperature. Stop engine and connect clamp of Tachometer Set (J-33300-200) to No. 1 cylinder injection pipe. Attach alligator clip to ground. Install magnetic pick-up probe into TDC access slot. (Scheme 56) NOTE: To ease placement of probe in TDC access slot, it may be necessary to cut away a small portion of plastic shield underneath pump.
2. Ensure that probe insertion limiting device is placed at a depth of 1.47 in. (37.3 mm). Connect timing meter to battery. Place timing meter rocker switches to "MAGNETIC PICK-UP" and "CLAMP-ON/PICK-UP" positions.
3. Start engine. Set magnetic offset control for zero degrees. Observe timing on tachometer display. Injection pump timing should be about 8 degrees BTDC. If timing is incorrect, perform STATIC TIMING adjustment procedure. If timing is correct, go to next step.
4. Verify that throttle lever is seated against idle speed screw. Ensure that automatic advance lever is seated against stop. (Scheme 57) Make sure that both levers move freely.
5. If levers are not seated against stops, the automatic advance mechanism is partially engaged. Disengage advance mechanism by loosening clevis screw and rotating clevis 1/4 turn. DO NOT tighten screw at this time.
6. Read idle speed on tachometer. If idle speed is incorrect, loosen idle speed screw lock nut. Using idle speed screw, adjust idle speed to 800 RPM. Tighten lock nut. Stop engine.
7. Insert a.256" (6.50 mm) shim between automatic advance lever and stop. (Scheme 57) Check clearance between idle speed screw and throttle lever. Clearance should be.119" (3.00 mm). If clearance is correct, go to step 9). If clearance is incorrect, go to next step.
8. With.256" (6.50 mm) shim between automatic advance lever and stop, loosen ball stop. (Scheme 57) Move ball stop forward or rearward to obtain a.119" (3.00 mm) clearance between throttle lever and idle speed screw. Tighten ball stop, and go to next step.
9. Remove.256" (6.50 mm) shim. Reposition clevis so it will engage with cable of cold start capsule. Tighten clevis screw. (Scheme 57) Remove tachometer.

Scheme 57

Static Timing

1. Remove screw plug and copper washer from center of 4 high pressure outlets on rear of injection pump. Install Dial Indicator Support (Mot. 856) in place of screw plug. Insert stem of dial indicator into support. (Scheme 53)
2. Loosen cold start throttle cable set screw, move levers back slightly, and rotate clevis pin 1/4 turn to disengage cold start system. (Scheme 54)
3. Rotate crankshaft clockwise (viewed from front of engine) 1-1/2 turns. Dial indicator will stop moving when injection pump piston is at BDC position. With pump piston at BDC, zero dial indicator. NOTE: With injection pump piston at BDC position, the pump shaft keyway should be positioned just before centerline of No. 1 fuel outlet fitting.
4. Remove screw plug from TDC access hole in cylinder block, and install TDC Rod (Mot. 861). (Scheme 55) Slowly rotate crankshaft clockwise until TDC rod can be inserted into TDC hole in crankshaft counterweight.
5. With TDC rod in hole, dial indicator should read.031-.033 in. (.79-.84 mm). This reading represents amount of piston lift. If reading is correct, go to step 8. If reading is incorrect, go to next step.
6. To increase piston lift, rotate pump toward engine, and then slowly rotate pump away from engine until correct reading is obtained. To decrease piston lift, slowly rotate pump away from engine until correct reading is obtained.
7. Remove TDC rod. Slowly rotate crankshaft clockwise 2 complete revolutions, until TDC rod can be reinserted into TDC hole in crankshaft counterweight. With TDC rod in hole, dial indicator should read.031-.033 in. (.79-.84 mm). If reading is correct, go to next step. If reading is incorrect, repeat steps 6 and 7.
8. Remove TDC rod from hole and install screw plug. Remove dial indicator and support. Install copper washer and screw plug. Compress timing control lever and install clevis pin. Hold lever against clevis and tighten set screw.

Scheme 58

Scheme 59

1. With engine cold (not started for at least 3 hours), verify that idle control lever is resting on lever stop. If lever is okay, go to next step. If lever is not resting on stop, loosen set screw and turn clevis 1/4 turn. (Scheme 58)
2. Rotate crankshaft clockwise 2 revolutions, remove screw plug from TDC access hole in cylinder block, and install TDC Rod. (Scheme 55) Move timing control lever to detent position. Ensure clearance between timing control lever and lever stop is.020 in. (.50 mm).
3. If necessary, adjust clearance by turning stop lever screw. Insert a.256" (6.50 mm) shim between control lever and lever stop. Insert a.119" (3.00 mm) shim between throttle lever and idle stop screw. Loosen ball joint nut. (Scheme 59)
4. Slide ball joint nut until it contacts throttle lever. Tighten nut. Determine proper clearance (shim thickness) between control lever and lever stop, according to temperature of cold start capsule. See «COLD START SYSTEM SHIM THICKNESS»(/jeep/wagoneer/xj-1984-1991/remont/testing-diagnostics/#fuel-injection-system-diesel) chart. COLD START SYSTEM SHIM THICKNESS Capsule Temp.: °F (°C) Shim Thickness: In. (mm) 66 (19) Or Less.2561 (6.505) 72 (22).2325 (5.905) 77 (25).2167 (5.504) 86 (30).1870 (4.750) 95 (35).1575 (4.0) 104 (40).1281 (3.254)
5. Insert correct shim between control lever and lever stop. Align clevis and throttle cable stop. Tighten clevis and throttle cable stop so that they both contact timing control lever.
6. Tighten throttle cable stop screw. Remove and reinsert shim between control lever and lever stop. Ensure that clearance is correct. Remove shim.
7. Start and run engine until it reaches normal operating temperature. Verify that throttle and timing control levers are against their respective stops. Ensure levers are not binding. Perform the DYNAMIC TIMING & IDLE SPEED adjustment procedures under «INJECTION PUMP TIMING»(/jeep/wagoneer/xj-1984-1991/remont/testing-diagnostics/#fuel-injection-system-diesel).

Fuel filter should be drained whenever "WATER IN FUEL" warning light glows. Diesel fuel can damage asphalt and painted surfaces. Always place a drain pan under fuel filter to collect contaminated fuel.

1. Stop vehicle and turn engine off. Attach a long piece of tubing to draincock outlet. Place end of drain hose into drain pan. Open filter assembly vent valve (Black cross-shaped knob) and drain-cock.
2. Drain approximately 1/2 pint (.24 L) from fuel filter. Close vent valve and draincock. Start engine and check for leaks. If "WATER IN FUEL" warning light comes on again, remove water contaminated fuel from fuel lines and fuel tank.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• TROUBLE SHOOTING