Fuel Injector: Testing and Inspection
Fuel Injector Electrical TestInjectors are monitored by the ECM and set a fault code if them fail electrically.
Disconnect injector connectors and measure resistance of injector windings.
Resistance between terminals 15 - 17 ohms
Fuel Injector Spay and Volume Test
NOTE: Make sure fuel system pressure is OK before performing this test procedure.
To test the injectors, the fuel rails must be removed with the injectors attached.
REMOVING FUEL RAILS AND INJECTORS
Fastener Locations For Air Filter Housing:
1. Remove air cleaner assembly and intake air ducts.
2. Remove the PCV hose from between valve covers.
3. Cut the cable holding tie on the rear of the fuel rail.
4. Remove the support clip for the engine wiring harness.
5. Disconnect electrical connectors from the throttle valve potentiometer, thermo-switch, and idle stabilizer valve and remove idle stabilizer valve.
6. Disconnect hoses to carbon canister.
7. Remove intake air temperature sensor from rear of intake manifold.
8. Disconnect electrical connectors from air mass sensor, knock sensors, and all fuel injectors.
9. Disconnect pressure regulator vacuum hose.
10. Remove fuel rail holding bolts and pull rails from manifold, leaving injectors attached.
TESTING INJECTORS
Fuel Pump Relay Socket Terminal ID:
1. Remove fuel pump relay and connect jumper wire between receptacle terminals #48 and #52 (turns fuel pump "ON")
Checking Fuel Injectors:
2. One at a time, place injectors into a graduated cylinder or other suitable measuring container and apply battery power and ground to electrical terminals for 30 seconds, while observing spray pattern.
^ Injectors should spray a cone shaped mist of fuel.
WARNING: Fire hazard! Use appropriate connectors and remote switch or long jumper wires so as not to create any sparks near the injector being tested. The mist of fuel can ignite very easily.
3. Note volume of fuel sprayed by injector in 30 seconds.
^ Volume should be 90ml - 100ml (3.0oz - 3.4oz).
If injection quantity of any injector is not within specification, replace that injector.
If injection quantity of all injectors is nearly the same but all are out of specification, check fuel system pressure. Testing and Inspection
4. With the fuel pump still operating, dry off the tips of all injectors and check for leaks.
^ Some wetting is normal and one or two drops per minute from each injector tip is acceptable. Any more than this is unacceptable and the injector should be replaced.
5. When testing is complete, remove jumper wire and re-install fuel pressure regulator. Re-assemble in the reverse order of disassembly.
NOTE: Leaking injectors and injectors with poor spray patterns can sometimes be cleaned with a chemical fuel system cleaner and re-used. Use a cleaner designed for fuel injectors. Also some gasolines contain a cleaning additive for fuel injection systems. If clogged or leaking injectors are suspected, switching to one of these gasoline brands may help.
6. If cleaning does not restore normal injector operation, replace the injector(s).