Fuel Injector: Testing and Inspection

Fig. 27 Testing injector resistance.:

1. Warm up engine and run at idle.
2. Using screwdriver or sound scope, check operating sound of injector.
3. If operating sound is not heard on 1986-87, check injector resistance, main relay, fuses and the control unit.
4. Disconnect connector from each injector one at a time.
5. If engine speed does not decrease 100-200 RPM for each injector on 1986-87 models, check injector resistance, injection volume of injector and the fuel pressure. On 1988 models, if there is no operating sound and no speed drop, perform quick inspection for electrical signal. If there is no speed drop only, check injector resistance and the injection volume of injector.
6. On 1988 models, perform quick inspection for electrical signal as follows:
a. Ground green, 1 pin test connector with a jumper wire.
b. Turn ignition switch to On position.
c. Open throttle valve and check for a click at injector with a screwdriver or sound scope as it is opened.
d. If nothing is heard, check injector wiring circuit.
e. If nothing is heard at all injectors, check main relay and circuit.
7. Check injector resistance as follows:
a. Check resistance between terminals Fig. 11.
b. If resistance is not 12-16 ohms (exc. 1988 turbo) or is not 11-15 ohms (1988 turbo), replace injector.

Fig. 13 Injector Rail:

8. On 1986-87 models, proceed as follows:
a. Disconnect battery ground cable.
b. Disconnect fuel hoses from fuel filter and the pressure regulator. Allow engine to cool before disconnecting fuel hoses and cover hoses with rag as fuel will be splashed out when disconnecting hoses.
c. Disconnect connector from each injector.
d. Remove pressure regulator on non-turbocharged models or reed valve housing on turbocharged models, the distribution pipe and the grommets, injectors and insulators Fig. 13.
e. Attach injectors to distribution pipe with wire. Attach injectors firmly to distribution pipe so that no movement of injectors is possible.
f. Connect distribution pipe assembly between fuel filter and return hose, then connect battery ground cable.
9. On 1988 models, proceed as follows:
a. Lift dynamic chamber upward.
b. Remove injectors and delivery pipe.
c. Affix injectors to delivery pipe with wire. Affix injectors firmly so that no movement is possible.
d. Connect terminals of fuel pump test connector with jumper wire.
10. On all models, check injectors for fuel leakage as follows:
a. Turn ignition switch on.
b. Connect both terminals of fuel pump check connector with jumper wire.
c. If fuel leaks from injector nozzle, replace injector. On 1986-87 models, a slight amount of fuel leakage after 5 minutes is acceptable. On 1988 models, a drop of fuel from injector after 1 minute is acceptable.
11. On 1986-87 models, check injector volume as follows:
a. Connect vinyl hose at least 39 inches in length to injector and place other end in graduated cylinder.
b. Connect terminals of fuel pump check connector with jumper wire.
c. Using injector checker 49 B092 953 or equivalent, apply battery voltage to each injector, then turn ignition switch on.
d. If injection volume is not 2.3-3.2 cubic inches on non-turbocharged models, or 3.8-5.2 cubic inches on turbocharged models, within a 15 second interval, replace injector.
12. On 1988 models, check injector volume as follows:
a. Connect tool 29B092953 or equivalent to battery and injector.
b. Check injection volume with graduated container.
c. If volume is not 2.68-3.72 cubic inches per 15 seconds (non-turbo) or is not 4.45-5.49 cubic inches per 15 seconds (turbo), replace injectors.