How To Check a Fuel Pump Relay

If you sense that your fuel pump is not working properly, there is a great possibility that your fuel pump relay is accountable. When your car does not start normally, you can conduct a test to your fuel pump relay to see if the problem arises from this area. These steps can help you identify whether your relay is functioning properly or you need to replace it.

  1. Locate fuel pump relay. The very first thing you should do is to locate the fuel pump relay in your car. The location of fuel pump relay varies from car to car. Most relays are positioned under the vehicle’s dashboard near the steering piece. Other fuel pump relays are located in the fuse box, or engine compartment, towards the firewall. After locating the position of your fuel pump relay, carefully unplug it and make sure that you will not break the lock tabs of the relay.
  2. Locate the two power circuit terminals and two control circuit terminals. Identifying these four circuit terminals can sometime be confusing. Most fuel pump relays have a diagram on its case indicating the location of these terminals. If this is not available, try looking at the wires that is connected at the mounting base of the relay. Normally, the two thin wires are the control circuit terminals and the remaining thick wires connect to the power circuit terminals.
  3. Test the continuity of the power circuit terminals. Once you located the power circuit terminals, use an ohmmeter to read the resistance value of the terminals. You can do this by setting the ohmmeter at its lowest range and touching the meter that leads to each of the power terminals. If you cannot detect an infinite resistance, you must replay the relay; otherwise, jump on to the next procedure.
  4. Connect jumper wires to the control terminal and positive terminal of the battery. Using the jumper wires, connect one end of the wire to one of the control circuit terminals of the relay and the other end to the positive terminal of your battery. Afterwards, attach a regular jumper wire to the remaining control terminal and the other end of the jumper wire to a good ground on your vehicle. When you touch the jumper wire to the ground, you should hear a click from the relay. If you were not able to hear such click, you need to replay the relay.
  5. Repeat step 3 but this time, leave the jumper wire connected to the control terminal. The final step in checking your fuel pump relay is test the continuity of power terminals while leaving the jumper wire attached to one end of the control terminal. This time, you should be able to detect a zero resistance value from your ohmmeter. If you read an infinite resistance, you need to replace the relay.

These are the steps on checking if your fuel pump relay is functioning well. Other signs that indicate a poorly functioning fuel pump relay involves: your car dies then starts minutes later, strange noise coming from your fuel pump, or the engine is not starting even after engaging the fuel pump switch.


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