Fuel Injector: Testing and Inspection

Fig. 23 On vehicle inspection, injectors.:

Steps 1 through 5 apply to non-turbocharged models only.
1. Using a mechanic's stethoscope, check operating sound of primary injectors from idle through acceleration Fig. 23.

Fig. 24 Secondary injector inspection.:

2. Disconnect vacuum hose from boost sensor.
3. Start engine and check operating sound of secondary injectors above 3500 RPM Fig. 24. If operating sounds are not heard in steps 1 and/or 3, proceed to step 4, otherwise, proceed to step 11.

Fig. 40 Checking resistance of solenoid resistor.:

4. Check resistance of crank angle sensor.
5. Check wire from crank angle sensor to control unit for continuity.
6. On 1986-87 models, check resistance of solenoid resistor, Fig. 40.
7. If resistance is not 5-7 ohms, replace resistor.
8. On all models, check EGI main fuse, replacing as necessary.
9. Check operating sound of main relay by turning ignition switch on and off.

Fig. 41 Checking continuity between terminals of main relay.:

10. Check continuity between terminals of main relay, Fig. 41. With no voltage applied, there should be no continuity between terminals A and B or between terminals C and D. With 12 volts applied, there should be continuity between terminals A and B and between terminals C and D.

Fig. 26 Fuel injection leakage testing.:

11. On non-turbocharged models, check injectors for fuel leakage as follows:
a. If checking primary injectors, remove dynamic chamber and the intake pipe.
b. Remove delivery pipe attaching bolts, then attach injectors to delivery pipe with wire Fig. 26. Attach injectors firmly to delivery pipe so that no movement of injectors is possible.
c. Connect terminals of fuel pump check connector with jumper wire, then turn on ignition switch.
d. Ensure fuel does not leak from injector nozzles. A slight amount of leakage after 5 minutes is acceptable.
12. On turbocharged models, check injectors for fuel leakage as follows:
a. Secure injectors to delivery pipe with wire. Attach injectors firmly so that no movement of injectors is possible.
b. Connect terminals of fuel pump check connector with jumper wire, then turn on ignition switch.
c. Ensure fuel does not leak from injector nozzles. A slight amount of leakage after 5 minutes is acceptable.

Fig. 27 Testing injector resistance.:

13. On all models, check resistance across terminals of each fuel injector Fig. 27. If resistance is not 1.5-3 ohms on 1986-87 models, or is not 12-16 ohms on 1988 models, replace injector.
14. Check injection volume as follows:
a. Attach injectors to delivery pipe as previously described.
b. On non-turbocharged models, connect vinyl hose at least 79 inches in length to injector.
c. On all models, connect injector checker 49 9200 040 or equivalent (1986-87) or tool 49B092953 or equivalent (1988) to injector.
d. Connect terminals of fuel pump check connector with jumper wire, then turn ignition switch on.
e. Connect injector checker to battery and check injection volume with graduated container. Injection volume should be 6.8-7.2 cubic inches on non-turbocharged models, or 8.1-8.7 cubic inches on turbocharged models within a 15 second interval.