Fuel Injection System - 2.2l Diesel Chevrolet Cab & Chassis C20

COMPONENT TESTING

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

DESCRIPTION

The fuel injection system consists of a combination injection pump and fuel distributor, 4 injection nozzles, a fuel tank, lines and hoses, and fuel filter assembly. The filter assembly contains a fuel filter, integral priming pump, and a water separator. The injectors use a needle type valve at the end of each nozzle.

The glow plug system uses 4 glow plugs to assist in cold starting. The thermal glow plug system has a controller, relays, thermo switch, dropping resistor, sensing resistor, and glow plugs. Warning lights in the instrument cluster indicate when the glow plugs are operating or the fuel filter is filled with water.

FUEL INJECTION PUMP

The injection pump is located on the lower right side of the engine and is driven by a toothed belt. It draws fuel from the tank, pressurizes it and sends a specific quantity to each cylinder at the proper time. Excess fuel from the injectors is returned to the fuel tank.

A fast idle system is used when coolant is below a specific temperature. A vacuum unit actuates the throttle to increase idle speed.

A fuel cut solenoid is actuated by the ignition switch, stopping fuel flow at the pump to shut down the engine. The injection pump is also equipped with an altitude compensator for proper fuel delivery at high altitudes.

INJECTION NOZZLES

Injection nozzles spray fuel into a prechamber as each compression stroke occurs. A fuel return line connects all injectors and returns excess fuel to the pump. Injectors are opened by high pressure in the fuel lines. Injector opening pressures are adjustable, using an adjustment screw in the injector nozzle. If spray patterns are incorrect, nozzles can be overhauled.

FUEL FILTER & WATER WARNING SYSTEM

The diesel injection system uses an integral fuel filter and water separator. A water sensor is fitted into the bottom of a fuel filter cartridge and lights a warning lamp when water accumulates in the filter. A hand pump is also incorporated into the filter housing to prime the pump after filter replacement.

GLOW PLUGS

The glow plug system uses 4 glow plugs to assist in cold starting. When engine coolant is below 122°F (50°C), the No. 1 relay supplies battery voltage to heat the glow plugs quickly.

When the glow plugs reach maximum temperature, relay No. 1 is turned off and relay No. 2 provides a lower voltage to maintain glow plug temperature. When the engine starts, the glow plug system is turned off. At coolant temperatures above 122°F (50°C), only relay No. 2 is operated. This operation provides easy starting but does not drain the battery or overheat glow plugs.

HARD STARTING

Check fuel delivery, injection pump timing and nozzle opening pressures. Check fuel cut solenoid and fuel restrictions. Air leaks.

ROUGH IDLE

Adjust idle speed. Contaminated fuel, injection timing, nozzle opening pressure or sticking delivery valve in pump.

LACK OF POWER

Air cleaner restriction. Accelerator linkage. Exhaust restriction. Fuel contamination or restriction in lines. Injection timing.

EXHAUST SMOKE

Check for air cleaner restrictions or contaminated fuel. Injection timing or nozzle opening pressure.

GLOW PLUG INDICATOR INOPERATIVE

Check for burned out bulb, blown fuse or fusible link. Bad connections at controller. Controller or ignition switch defective.

IMPROPER OPERATION OF GLOW PLUGS

Thermal sensor or glow plugs defective. Controller inoperative. Ignition switch "R" circuit intermittent or open.

Spray Pattern

Remove nozzles and mount on injection nozzle tester. Pump tester lever about 1 stroke every 2 seconds to observe spray pattern. (Scheme 73) If spray is faulty, injector must be cleaned or replaced.

Injection Nozzle Spray Patterns. Scheme 73

Opening Pressure

1. Pump pressure up slowly to note opening pressure. If opening pressure is less than 1493 psi (105 kg/cm 2 ) injector must be cleaned or replaced.
2. Check injector nozzles for leakage by installing in tester and maintaining a pressure of 285 psi (20 kg/cm 2 ). If leakage is evident, injector must be cleaned or replaced (slight wetting around tip after 10 seconds is OK).

Scheme 74

Scheme 75

1. Disassemble injector nozzle. If nozzle needle is damaged, fused, seized or discolored, replace entire nozzle assembly. Check all other parts for excessive wear or damage. Replace as needed. (Scheme 74)
2. Scrape off carbon deposits with a piece of wood and clean each part in clean solvent. After cleaning, keep parts immersed in light oil. Be sure to remove all deposits from components. Nozzle must be replaced if needle seats are worn or damaged.
3. Hold nozzle vertically and insert needle. Lift needle about 1/3 way out of nozzle and release. Needle should slide smoothly back into place. Repeat procedure several times, rotating needle slightly each time. If needle does not slide smoothly, replace nozzle body and needle. (Scheme 74): Injection Nozzle
4. When assembling injectors, use Centering Gauge (J-33178) to install nozzle in center of nozzle body holder. (Scheme 75) Tighten retaining nut to 65 ft. lbs. (88 N.m). (Scheme 75): Centering Injector Nozzle
5. After tightening retaining nut, draw out centering tool. If it can't be drawn out easily, nozzle body has not been fitted properly. Loosen retaining nut and tighten properly. Adjust nozzle opening pressure after assembly.

Glow Plug Relays

No continuity should be present across terminals "C" and "D". With battery voltage applied to terminals "A" and "B", continuity should be present across "C" and "D". If not, replace relay. (Scheme 76)

Glow Plug Relay Testing. Scheme 76

Dropping Resistor

Check for continuity across terminals of resistor. If no continuity, replace resistor. Resistor is located on right front fender near battery.

Continuity should exist between plug end terminal and body. If not, replace plug.

Thermo Switch

Continuity should exist when switch temperature is lower than 117-127°F (47-53°C). No continuity should exist when above 127°F (53°C). If switch does not operate properly, replace it.

Glow Plug System Wiring Diagram. Scheme 77

INJECTION PUMP & TIMING BELT

Note. When timing belt is loosened or removed, it must be replaced. DO NOT re-tension or install a used timing belt.

Removal

1. Disconnect negative battery cable. Align crank pulley with timing pointer, loosen belts and remove pulley. Remove power steering reservoir and upper fan shroud. Remove fan and fan drive pulley. Remove upper timing belt cover.
2. Remove alternator belt and lower timing belt cover. Remove injection pump timing pulley flange bolts. Remove tension spring using care not to distort spring. Remove tension pulley center nut, then remove pulley and center. Remove timing belt.
3. Remove injection pump gear. Remove fuel feed and return lines from pump. Disconnect electrical wiring, throttle cable and injection lines. Remove throttle return spring. Raise vehicle and remove injection pump-to-bracket bolts. Lower vehicle and remove pump.

Note. If injection pump bracket is removed, refer to INJECTION PUMP TIMING procedure.

Scheme 78

1. Install injection pump, aligning marks on flange and front bracket. Install injection pump pulley, using holding bolt to keep pulley from turning. Set No. 1 cylinder at TDC compression stroke.
2. Align pulleys so marks are together. (Scheme 78) Install timing belt on crankshaft pulley, camshaft pulley and injection pump pulley in order. Position belt so slack is in area of idler pulley. (Scheme 78): Timing Belt Pulley Alignment
3. Install tension pulley with base aligned against 2 pins on timing pulley housing. Hand-tighten center nut. Install spring and tighten nut until snug. Turn crankshaft 2 revolutions, then 90° more beyond TDC. CAUTION: Always turn engine in firing rotation. DO NOT rotate in reverse direction.
4. Loosen tension pulley nut so pulley can take up belt slack, then tighten nut to specification. Install injection pump pulley flange so hole in flange is aligned with mark on camshaft pulley. Turn engine 2 revolutions and check that marks are still aligned with No. 1 cylinder at TDC compression stroke.
5. Belt tension between injection pump pulley and crankshaft pulley should be 33-55 lbs. (15-25 kg) when measured with tension gauge. To complete installation, reverse removal procedure. Adjust injection timing.

Removal & Installation

1. Disconnect negative battery cable. Disconnect water sensor wiring at connector. Disconnect water sensor-to-main body hose. Remove filter cartridge and pour out fuel. Remove water sensor.
2. Lubricate sensor "O" ring with diesel fuel and install sensor on new filter cartridge. Lubricate gasket with fuel, then install filter cartridge. Tighten 2/3 turn after filter contacts base.
3. Reconnect water sensor wiring and hose. Disconnect filter-to-injection pump fuel line at pump and place open end in container. Pump hand pump until fuel flows from fuel line. Reconnect fuel line to injection pump. Start engine and check for leaks.

Draining Water

1. Place 2-quart container under drain hose. Open drain plug about 4 turns and operate hand pump until all water is removed from filter. Tighten drain plug.
2. Operate pump several times until pressure builds up. Start engine and check for leaks. "WATER IN FUEL" lamp on dashboard should be off. If light remains on, fuel tank must be drained.

Fuel Filter and Water Separator. Scheme 79

INJECTION PUMP TIMING

1. Check that notch in pump flange is in line with notch in front bracket. Set No. 1 cylinder at TDC compression stroke. Remove injection pump pulley cover (right half of timing belt cover) to ensure timing marks are aligned. (Scheme 78)
2. Disconnect injection pipe from pump (using back-up wrench) and remove distributor head screw. Install Timing Gauge (J-29763) and set lift approximately.04" (1 mm) from plunger.
3. Turn engine until No. 1 cylinder is 45-60° BTDC. Set dial indicator to zero. Turn crankshaft pulley slightly in both directions to check that zero reading does not change.
4. Turn crankshaft in normal direction of rotation until timing mark (15° BTDC or 13°BTDC for California models) on crankshaft pulley is in line with indicator. (Scheme 80) Dial indicator should show.020" (0.5 mm). If not, loosen pump bolts and rotate pump slightly to obtain proper timing.

Timing Mark Identification. Scheme 80

ADJUSTMENT

Note. For all on-vehicle adjustments, see appropriate TUNE-UP article.

An auxiliary vacuum pump is used on diesel engines. The pump is belt-driven off the crankshaft pulley and supplies vacuum for the power brake booster and any vacuum-operated accessories.

Testing

1. Disconnect vacuum pump-to-brake booster hose at pump and attach vacuum gauge to fitting. Disconnect vacuum outlet hose. Plug hose ( DO NOT plug pump fitting). With engine at idle speed (800 RPM), vacuum should be at least 21 in. Hg within 30 seconds.
2. If vacuum is low, check gauge and connections for leaks. Check belt tension and idle speed. If reading is still low, replace pump.
3. Install a "T" fitting in vacuum hose between pump and brake booster. Attach vacuum gauge at "T". Run engine at idle for about 1 minute. Vacuum should be no more than 3 in. Hg lower than in step 1).
4. If vacuum is too low, check gauge and connections for leaks. If reading is still low, check power booster and any vacuum operated accessories for leaks. Repair or replace as needed.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS