Tune-Up - Diesel Chevrolet Forward Control P30

ENGINE IDENTIFICATION

Engines can be identified by the eighth character of Vehicle Identification Number (VIN) which is stamped on a tag at the top left corner of dashboard. The 2.2L engine VIN number also appears on left front of cylinder block above crankshaft pulley.

The 6.2L engine is also identified by code letters, located on a label at rear of left valve cover and also stamped into block on left front corner.

VIN ENGINE CODES

TUNE UP NOTES

Note. When performing tune-up procedures described in this article, these notes and precautions must be followed.

Due to late changes and corrections, always refer to Engine Tune-Up Decal in engine compartment before attempting tune-up. If decal specifications are different than specifications given in this manual, use decal specifications.

Adjustment of injectors or internal adjustment of injection pump must be done in a properly equipped injector shop with clean environment.

Prior to checking compression, be sure battery is fully charged to avoid battery run down. When turning engine over during test, 6 "puffs" per cylinder should be used to obtain reading.

ENGINE COMPRESSION

Note. Do not add oil to cylinders during compression check as extensive engine damage will result.

2.2L

1. Start engine and bring coolant temperature to 176°F (80°C). Remove sensing resistor, glow plug connector and fuel cut solenoid connector. Disconnect fusible link wire of glow plug system. Remove all glow plugs.
2. Install adapter (J-26999-20) and compression gauge. Turn starter motor and read compression for individual cylinders.

6.2L

1. Remove air cleaner. Disconnect electrical wire from fuel injection pump solenoid terminal.
2. Disconnect glow plug wiring, and remove all glow plugs. Use compression gauge (J-26999-10) to test individual cylinders.

COMPRESSION SPECIFICATIONS

1. E-I-I-E-E-I-I-E (Front-to-rear).

1. I-E-I-E-I-E-I-E (Left bank, front-to-rear).
2. E-I-E-I-E-I-E-I (Right bank, front-to-rear).

1. Tighten rocker arm shaft bolts to 9-17 ft. lbs. (12-23 N.m). Bring No. 1 piston to TDC of compression stroke. Adjust intake and exhaust valves on No. 1 cylinder. Adjust intake valves on No. 2 and No. 3 cylinders.
2. Turn crankshaft one revolution and adjust intake and exhaust valves on No. 4 cylinder. Adjust exhaust valves on No. 2 and No. 3 cylinders.

VALVE CLEARANCES - 2.2L (ALL VALVES)

The 6.2L engine uses hydraulic lifters with roller followers. Adjust to zero lash.

Glow plugs are of the fast glow type (fast warm-up). During start and warm-up modes, engine is electronically controlled to provide fast cold starts and good cold driveaway.

The glow plug system consists of an electronic control module, glow plug relays 1 and 2, a dropping resistor, sensing resistor, thermo switch and fusible links.

A fast chamber preheat is provided if engine coolant temperature at thermo switch is below 122°F (50°C). Relay 1 is then energized and the glow plugs indicator lamp is on for a period of 3.5 seconds or more, before going out. Chamber preheat temperatures permit starting the engine.

At engine coolant temperatures above 122°F (50°C), relay 1 is inoperative and relay 2 turns on to provide stabilizing heat during starting.

Glow plugs are small 6-volt heaters operated by an electronic relay. They cycle on and off, powered by 12 volts to give rapid heating. Glow plug light on dash should lit as plugs cycle on and off.

If test lamp is connected to glow plugs and ground, it should flash on and off. Relay can be heard clicking on and off after ignition has been on for approximately 25 seconds.

GLOW PLUG SPECIFICATIONS

2.2L Firing Order. Scheme 11

6.2L Firing Order. Scheme 12

Scheme 13

1. Check that notched line on injection pump flange is in alignment with notched line on injection pump front bracket. Bring No. 1 piston to TDC of compression stroke.
2. Remove upper fan shroud. Check that timing belt is properly tensioned and that timing marks are aligned. If not, remove belt and readjust. Remove injection lines and remove distributor head screw and washer.
3. Install dial indicator (J-29763) and set lift to 0.04" (1 mm) from plunger. Bring piston in No. 1 cylinder to a point 45-60° BTDC by turning crankshaft. (Scheme 13) Calibrate dial indicator to zero. (Scheme 13): 2.2L Injection Pump Timing
4. Turn crankshaft pulley slightly in both directions and check that gauge indication is stable. Turn crankshaft in normal direction of rotation and take reading when timing mark on crankshaft pulley is aligned with pointer.
5. Dial indicator should read.020" (0.5 mm). If reading is not as specified, hold crankshaft in place (15° BTDC) and loosen 2 nuts on injection pump flange.
6. Move injection pump to a point where dial indicator reading is.020" (0.5 mm) and tighten pump flange nuts. Recheck dial indicator reading and readjust if necessary.
7. Install distributor screw and washer into injection pump. Install injection lines. Connect wires and hoses previously removed. Install upper dust cover. Install timing belt, if removed. Install fan shroud. Adjust engine idle speed and fast idle speed.

1. Check alignment of injection pump timing marks on top of engine front cover and injection pump flange. Half circles on California models, scribe marks on Federal models.
2. If timing marks are not aligned, loosen 3 retaining nuts, and align mark on injection pump with mark on front cover. Tighten nuts to 30 ft. lbs. (41 N.m) and adjust throttle linkage.

Scheme 14

1. Set parking brake and block drive wheels. Place transmission in Neutral. Connect tachometer. Start engine and warm to normal operating temperature. Loosen lock nut on idle speed adjusting screw. (Scheme 14) (Scheme 14): 2.2L Idle Speed Adjustment
2. Turn adjusting screw to obtain curb idle speed. Tighten lock nut. Apply vacuum to fast idle actuator. Loosen lock nut on fast idle actuating screw. Adjust knurled nut to obtain fast idle speed. Tighten lock nut.

IDLE SPEED (RPM) - 2.2L

1. Set parking brake and block drive wheels. Warm engine to normal operating temperature and install tachometer (J-26925). Adjust low idle speed screw on pump to obtain curb idle speed. (Scheme 15)
2. Remove connector from fast idle solenoid. Run an insulated jumper wire from battery positive terminal to solenoid terminal to energize solenoid. Open throttle to ensure plunger is fully extended.
3. Adjust fast idle speed by turning plunger hex head. Turn off engine, remove jumper wire and test equipment. Install fast idle solenoid connector.

6.2L Idle Speed Adjustment Energize solenoid when adjusting fast idle. Scheme 15

IDLE SPEED (RPM) - 6.2L

VACUUM PUMP

The vacuum pump is designed to aid the engine in maintaining a proper vacuum level for the power brake system and other vacuum operated accessories. The vacuum pump is a diaphragm type pump which requires no periodic maintenance.

The vacuum pump on 2.2L engines is belt-driven. Vacuum pump on 6.2L engines are either belt-driven or gear-driven.

Gear-driven pump is driven by a cam inside drive assembly to which it mounts. Drive housing assembly has a drive gear on lower end, which meshes with cam gear in the engine. Drive gear causes cam in drive housing to rotate.

Scheme 16

1. Connect vacuum gauge to vacuum pump inlet. If equipped, disconnect outlet hose from outlet tube on pump and plug end of hose. Do not plug vacuum pump outlet tube. With engine idling, vacuum should reach 21 in. Hg at sea level in 30 seconds. (Scheme 16)
2. If pump is okay, leak is in system other than at pump. Go to step 3). If reading is low or fluctuates, check gauge and connections for leaks. Check drive belt and idle RPM. If okay, go to step 3). If vacuum is still low, replace pump. (Scheme 16): Vacuum Pump Diagnosis Minimum acceptable vacuum shown at specified altitude.
3. Where applicable, remove plug from outlet hose and reconnect hose to pump outlet tube. Reconnect vacuum hose with a "T" and vacuum gauge located near pump inlet.
4. With engine idling, vacuum may be 3 in. Hg less than measured in step 1). If vacuum is okay, problems are not within vacuum system. If vacuum is low, check all attaching hoses and accessories for leaks.

Opening Pressure

1. Using a reliable nozzle tester and SAE J9670 calibrating oil at room temperature, check opening pressure. Connect test line to nozzle holder assembly and tighten fittings.
2. Close gauge valve and operate tester handle sharply several times. Check for proper nozzle position. Spray should be injected into a clean container. Open gauge valve and operate tester handle slowly to determine injection opening pressure.
3. Observe gauge reading just before oil is sprayed from tip. A buzzing noise will occur when spray is injected. Minimum opening pressure is 1493 psi (105 kg/cm 2 ).

Spray Pattern

Close pressure gauge. Check spray pattern by operating handle one stroke every 2 seconds. Observe spray pattern. Spray should be uniform and injected at correct angle of nozzle being tested.

Leakage

Apply 284 psi (20 kg/cm 2 ) pressure to nozzle. Nozzle tip should remain dry without an accumulation of fuel at spray holes. A slight wetting is allowed after 10 seconds if no droplets are formed.

1. Using a reliable nozzle tester and ISO 3104 testing oil at room temperature, check opening pressure. Connect test line to nozzle holder assembly and tighten fittings.
2. Close shutoff valve at pressure gauge and operate tester handle sharply several times. Check for proper nozzle position. Spray should be injected into a clean container.
3. Open shutoff valve at pressure gauge 1/4 turn. Operate tester handle slowly to determine injection opening pressure. Observe gauge reading just before oil is sprayed from tip. Minimum opening pressure is 1500 psi (105 kg/cm 2 ).

Open shutoff valve at pressure gauge 1 turn. Apply 1400 psi (98 kg/cm 2 ) pressure to nozzle. Tip should remain dry. A drop is allowed after a period of 10 seconds if no droplets are formed.

6.2L Engines Only

1. Loosely assemble throttle position switch to fuel injection pump with throttle lever in closed position. Attach a continuity meter across terminals (Pink wire and Yellow wire on light duty engines).
2. Insert proper "switch-closed" gauge block, between gauge boss on injection pump and wide open stop screw on throttle shaft. Rotate and hold throttle lever against gauge block.
3. Rotate throttle switch clockwise (facing throttle switch) until continuity pivot occurs (high meter reading) across terminals. Hold switch body at this position and tighten mounting bolts to 48-50 INCH lbs. (5-7 N.m). NOTE: Switch point must be set only while rotating switch body in clockwise direction.
4. Release throttle lever and allow it to return to idle position. Remove "switch-closed" gauge block and insert "switch-open" gauge block. Rotate throttle lever against "switch-open" gauge block. There should be no continuity across terminals.
5. If no continuity exists, switch is set properly. However, if there is continuity, then switch must be reset by returning to step 1) and repeating entire procedure. (Scheme 17)

TPS GAUGE BLOCK SPECIFICATIONS

6.2L Throttle Position Switch Adjustment Rotate clockwise until continuity occurs. Scheme 17

6.2L Heavy Duty (VIN J)

1. Attach vacuum regulator valve snugly, but loosely to fuel injection pump. The valve body must be free to rotate on pump. Attach a vacuum source of 18-21 in. Hg to bottom of vacuum nipple.
2. Attach vacuum gauge to top vacuum nipple. Insert vacuum regulator gauge bar (.646") between gauge boss on injection pump and wide open throttle valve stop screw on throttle lever.
3. Rotate and hold throttle shaft against gauge bar. Slowly rotate vacuum regulator valve clockwise (facing valve) until vacuum gauge reads 7.4-8.6 in. Hg. Hold valve body in this position, and tighten mounting screws to 48-60 INCH lbs. (5-7 N.m).
4. Valve must be set while rotating valve body in a clockwise direction only. Check by releasing throttle shaft, allowing it to return to idle stop position. Rotate throttle shaft back against gauge bar and determine if vacuum gauge reads within 7.4-8.6 in. Hg. If vacuum is outside limits, reset valve.

FUEL INJECTION

All 2.2L engines are equipped with Kiki diesel fuel injection. All 6.2L engines are equipped with General Motors diesel fuel injection.

ALTERNATOR REGULATOR

All models are equipped with Delco non-adjustable regulators, integral with alternator.

REGULATOR SPECIFICATIONS @ 85°F (29°C)

BATTERIES

All models use Delco "Freedom" type batteries. All V8 diesel vehicles use two 12-volt, negative ground, sealed-top batteries. One battery is located on each side of engine compartment and they are wired in parallel. The 2.2L uses one 12-volt battery.

BATTERY SPECIFICATIONS

STARTER

STARTER SPECIFICATIONS

ALTERNATORS

On 6.2L, alternator supplies current to both batteries. There are no switches or relays in charging circuit.

ALTERNATOR SPECIFICATIONS

BELT ADJUSTMENTS

BELT ADJUSTMENT (TENSION IN LBS. (KG) USING STRAND TENSION GAUGE)

SERVICE INTERVALS

REPLACEMENT INTERVALS

CAPACITIES

SYSTEM REFRIGERANT CAPACITIES

FLUID CAPACITIES