Q:

How do you check a fuel pump?

A:

Quick Answer

To check the fuel pump, you need a multimeter to check the voltage that your pump needs and to test the positive and negative leads. Determining the wires for the fuel pump and for the fuel gauge is the most challenging part of the testing process.

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Full Answer

While someone turns your vehicle’s key to the "run" position, stand next to the fuel pump. If you do not hear a humming sound for a few seconds, the pump or its connections might be faulty.

Check the fuel pump fuse before checking the inertia switch. If both are in good condition, determine which wires are for the pump. Usually, these are the two largest wires running out of the top of the electric pump. The smaller two are typically for the gauge.

To test the pump, the red multimeter probe should be in contact with the positive pump wire and the negative wire with the frame of the vehicle. You should have a voltage within 0.5 volts. Next, place the red probe on the negative pump wire. The voltage should be less than 0.5 volts.

While the key is "on," establish whether the wires are carrying the needed current by connecting the positive lead to the battery and the negative lead to the fuel pump’s power wire. You should have 0.5 volts or less. Then, move to the negative side and carry out the same test. If you see these numbers, but the pump does not deliver any fuel, the pump has a problem.

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