The fuel injectors on a 1987 Pontiac Sunbird are part of a multi-port fuel injection system. The fuel injectors are actuated by pulses from the engine control module (ECM). These pulses are timed by inputs from the mass air flow (MAF) and other sensors. The MAF output can be affected by a dirty air filter or leaks in the intake manifold. The injectors receive fuel from the fuel rail that is supplied by the fuel pump located at the gas tank.
Tools Used: Screwdriver, Stethoscope (optional), Injector test light, Ohmmeter
Test a Fuel Injector
Set the blade of a screwdriver on the fuel injector while the engine is running. Place your ear near the handle of the screwdriver and listen for clicking sounds. Note: You can also use a stethoscope for this test. Clicking indicates a functioning fuel injector. Stop the engine and proceed to the next step if clicking is not present.
Disconnect the electrical connector at the fuel injector by removing the retaining clip with a screwdriver. Start the engine and place the leads of an ignition test light on the connector. If the light does not flash, pulses are not coming from the ECM, which means the fuel injector is not the problem. If the light flashes, turn the engine off and proceed to the next step.
Place the leads of an ohmmeter on the fuel injector contacts. The resistance reading should be between 11.8 and 12.6 ohms. A reading outside this range indicates a defective fuel injector.
Tips & Warnings
If the fuel injector tests normal, reattach the electrical connector before going to the next injector.
Keep hands, hair and clothing away from moving parts when performing the tests.
Do not disconnect any fuel system part without first depressurizing the fuel system.
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