Fuel Pump Relay: Can It Work Intermittently? Why? [Explained]

If you are experiencing problems with your fuel pump not working, you may be able to fix the problem by replacing the relay. The relay is responsible for providing power to the fuel pump when you press down on the gas pedal. If it does not work properly, your fuel pump will stop working once in a while.

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Can a fuel pump relay work intermittently?

Yes, a fuel pump relay could work intermittently for the following reasons:

  1. Loose terminals – If there is no tight connection between the positive and negative terminals and the coils (they may turn out to be loose), it can cause problems like the pump not starting or working at times.
  2. Bad ground – The fuel pump relay is to be grounded properly. If this happens, the contacts will have a problem and may work intermittently.
  3. Contacts – Unlike other relays, the contacts in a fuel pump relay wear down over time which can cause problems with turning on and off of the pump.
  4. coil – This is somewhat similar to a spark coil which gets weak over time and causes problems with the starting of the pump.
  5. No start – If you turn on your ignition but your car won’t start, it could be an issue with the fuel pump relay. In case the power supply to the relay is not as required, it may not work and your car will not start. In some cases, it could be a bad connection on the positive side of the terminal which may prevent the fuel pump from working.

A fuel pump relay works by having two sets of contacts. When you press down on the gas pedal, electricity flows from the battery to one set of contacts and then through to the other set in order to supply power to your fuel pump.

It is important that both sets are connected properly or else it will not work. A relay can stop working because the contacts have become misaligned, corroded or there is a break somewhere in the wiring.

If a fuel pump relay works intermittently, it means that the problem is not with the set of contacts that supply power to your fuel pump but rather with one of its own sets.

In order to determine which set is the problem, you can do a voltage drop test. To perform this test, you would need to use either a voltmeter or an ohmmeter so that you can determine how much the electricity flows through certain sets of contacts.

Symptoms of a bad fuel pump relay

Some of the symptoms you may notice if your fuel pump relay is not working include:

  1. Engine stalls- If your engine keeps on stalling and you notice that the fuel pump does not work, it could be an issue with the relay. Try starting your car back up and if it doesn’t go too far without stalling again, then it is likely that the problem lies with your fuel pump.
  2. Engine does not start– The engine may still crank when the key is turned on, however it will not be able to start due to lack of fuel.
  3. Fuel pump does not make any noise – If you press down on the gas pedal and the pump makes no noise, it indicates that it is not working.

Can you bypass a fuel pump relay?

Yes, you can bypass a fuel pump relay, it is called jumpering or hardwiring a fuel pump. In this case, jumpering means wiring the pump directly from the battery.

When you bypass a fuel pump relay, what you are doing is putting a constant 12V supply to the fuel pump so that it runs constantly no matter what position the key switch is in or whether the engine has been started. This bypass method, therefore, makes your fuel pump run all the time, whether your car is running or not.

There is a good reason the key switch has the fuel pump relay built-in: to protect your car’s wiring circuit from damage caused by high current draw.

Does fuel pump need relay?

Yes, fuel pumps need a relay because it prevents your ignition switch from overheating. The run circuit (which the pump would traverse) was designed for a limited number of amps to transit through the contacts. It’s conceivable that adding fuel pumps, electric fans, and other accessories might burn up the connection.

Will fuel pump prime if relay is bad?

The fuel pump operates when the engine is cranked (not running) using power from the battery through the starter solenoid. When you turn on the key, this energizes a relay that in turn provides power to the fuel pump. If this relay fails, there is no way for electrical power to reach the pump and it will not operate.