If you have problems such as hard starting or stalling, you need to test your fuel pump relay and this is quite common work for automotive technicians. The fuel pump relay sends electrical power to the electric fuel pump, and the engine of a vehicle will suffer if it fails. How to Test Your Fuel Pump Relay
The first way is to listen for the fuel pump priming. When you turn the key to the on position (DO NOT start) you should hear a faint hum from the insid of the fuel tank for about 2 seconds. During this test, you should hear the pump run (the sound of the relay operating and sending juice to the pump so it can pressurize the fuel system). If you are not hearing this sound, that can be a sign of bag relay or even bad fuel pump.
To check the relay the best and less rely solution is to use a Multimeter. First, find the relay in your car fuse box Remove the relay and check for voltage between the relay terminals with a multimeter. Usually 12 volts will be present if the fuel pump relay is working. If there is no reading or the voltage is not correct, there may be an issue with the relay and it will need to be replaced. Fuel pump relay replacement typically costs anywhere between $20 and $50 to just replace the relay itself — a much less expensive repair than replacing the fuel pump.
Another way to do this is by simply swapping the fuel pump relay, with a working relay from the fuse box as long it has the same specs. For other systems (like A/C or headlights), many vehicles use relays that are identical to these. If replacing the relay fixes the problem and you are able to get the fuel pump working, then that is your issue.
The 2020 report from CarMD revealed that about 5% of vehicle no-starts are related to fuel systems such as bad relays. Early relay testing can save additional repair headaches, such as a $400-$600 laboring of damaged fuel pump.
A defective fuel pump relay can also cause a check engine light to come on. When fuel pressure is monitored continuously by the engine control unit (ECU), it also has diagnostic trouble codes (DTCs) like P0230 (Fuel Pump Primary Circuit Malfunction) that may be stored when the ECU detects inconsistencies due to the fuel pump not being sent power. If you have an OBD-II scanner then scan for these codes and that can help you to confirm the relay as the potential issue.
To quote automotive pioneer Henry Ford, Therefore believe every single piece has their area in the device. Even though it is a tiny component, the fuel pump relay plays an essential role in the operation of the fuel system.
Wrap Up | You can test your fuel pump relay by listening for the pump on prime, checking voltage with a multimeter, or swapping relays. To read on diagnoses and how to replace your fuel pump visit Fuel Pump.