Testing the Wiring

Most car electric fuel injection pumps are fitted inside of the fuel tank. To test the fuel pump first listen for it priming up when the ignition is first switch on,(note fuel pump will only run continually when the engine is turning over, either cranking on starter or once engine has started) If you can’t hear it running next check the fuses and that the inertia switch has not tripped if fitted.

Next look under the car to see where the fuel tank is and with somebody else cranking the engine over try banging the tank, sometimes a worn pump will work when jarred, if pump it does replace ASAP.

If the tank is under the rear seat remove this and see if there is an inspection cover over the fuel pump. If there is we need to check the wiring here if not you have to try and find a connector in the wiring loom and test here. There will normally be more than 2 wires, this is because the fuel gauge tank sender will normally be part of the pump assembly, and the 2 pump wires will be the thicker ones.

Testing Fuel Pump
Testing Fuel Pump Earth

If possible do not disconnect the connector, but push a paper clip into it to test, this way we can test it under load and not miss a poor connection. With engine turning and one end of your meter connected to a good earth point on the body, you want to see battery voltage (12v) on the +live one and less than 0.5 on the –earth connection. If we have these voltages the pump is faulty, if we do not get battery voltage (12v) you need to find the fuel pump relay and test this next, see relays. If you see more than 0.5v on the earth connection, you will need to trace this wire to where it bolts to the body, where it will normally be corroded or loose.

Click for video of testing fuel pumps

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