Gear Group (Front)

TM 9-2320-312-24-2

Testing and Adjusting Section

i01851185

i01280287

Gear Group (Front) - Time

Unit Injector - Test

SMCS Code: 1206-531

SMCS Code: 1290-081

This procedure assists in identifying the cause for

an injector misfiring. Perform this procedure only

after performing the Cylinder Cutout Test. Refer to

Troubleshooting, "Injector Solenoids Circuits Test"

for more information.

1. Check for air in the fuel, if this procedure has not

already been performed. Refer to Testing and

Adjusting, "Air in Fuel - Test".

Electrical shock hazard. The electronic unit injec-

tor system uses 90-120 volts.

2. Remove the valve cover and look for broken

parts. Repair any broken parts or replace any

broken parts that are found. Inspect all wiring for

the solenoids. Look for loose connections. Also

look for frayed wires or broken wires. Ensure

g00943251

Illustration 51

that the connector for the unit injector solenoid

Front gear group

is properly connected. Perform a pull test on

(1) Camshaft gear and timing reference gear

each of the wires.

(2) Timing marks

(3) Idler gear

3. Look for signs of fuel leakage. Investigate the

(4) Crankshaft gear

source of the leaking fuel. Remedy the cause of

Correct fuel injection timing and correct valve

the fuel leak.

mechanism operation is determined by the timing

4. Check the valve lash setting for the cylinder of

reference gear and the alignment of the front gear

group. The timing reference gear is located on the

the suspect unit injector. Refer to Testing and

camshaft gear. The timing reference gear is used

Adjusting, "Engine Valve Lash - Inspect/Adjust".

to measure crankshaft rotation. During installation

of the front gear, timing marks (2) on idler gear

5. Ensure that the bolts that hold the unit injector

(3) must be in alignment with the timing marks

are tightened to the proper torque. In order to

on crankshaft gear (4) and the timing marks on

check the torque, loosen the bolts that hold

camshaft gear (1).

the unit injector. Tighten the bolts to the proper

torque. Refer to either the Disassembly and

Check the teeth on the timing reference gear. The

Assembly Manual , "Unit Injector - Install" or the

teeth should not be defaced. The teeth should have

Specifications Manual , "Unit Injector - Install" for

sharp clean edges and the teeth should be free of

the proper tightening procedure.

contaminants.

Note: The electronic injection timing must be

calibrated after reassembly of the front gear train.

Refer to Troubleshooting, "Engine Speed/Timing

Calibration".