Checking the fuel injectors

If you suspect that one of the injectors is not working, this can be easily checked using an LED voltmeter and a precision ohmmeter.

PROCEDURE

Disconnect the connectors from all fuel injectors.

First, voltage check: connect an LED voltmeter (not a test lamp) to the terminals of the connector. Start the engine: the LEDs in the voltmeter should flicker; otherwise, there is no power supply or the ground-switching control module is faulty. This check cannot be performed with a conventional measuring instrument.

Resistance check: disconnect the injector connectors, connect an ohmmeter to both terminals of the injector: on a cold engine it should read 13.5 – 17 Ω.

If the reading is outside the specified limits, replace the injector (provided the measurement was accurate).

Leak check: remove the fuel distributor together with the injectors.

The injector connectors are disconnected, the fuel line hoses remain connected.

Have an assistant crank the engine several times with the starter so that the fuel pump operates and working pressure builds up.

Observe the fuel injectors: each individual injector must not lose more than 1–2 drops of fuel per minute. Otherwise, replace the leaking injector.

Independently of this, the injection spray pattern and injected quantity of the injector can be checked if necessary due to engine misfiring.