First, locate the relay in the vehicle’s fuse box or relay panel to check for malfunctioning of a Fuel Pump relay. A fuel pump relay is such a device that controls power to the fuel pump for its operation at the correct time. In case a relay fails, it will not allow the fuel pump to get power, hence causing the engine to stall or not start.
Check the fuse linked with the fuel pump relay. Fuses usually cost within a range of $1 to $5 and can be found in the fuse box, which is mostly under the dash or near the engine. If the fuse has blown, replace it with a new one with the same amperage rating. If the fuse happens to blow again after replacement, this could mean there may be an underlying problem such as a faulty relay. According to the National Institute for Automotive Service Excellence (ASE), around 12% of fuel pump failures are related to electrical issues, including problems with the fuel pump relay.
Next, test the relay itself using a multimeter to check for continuity. The multimeter should show a consistent reading when the relay is functioning properly. If there is no continuity when the relay is energized, this means that the relay has failed and should be replaced. Fuel pump relays are supposed to last the lifetime of the vehicle under normal conditions but can fail prematurely due to electrical overload, corrosion, or extreme temperatures.
If the relay has passed the continuity test, you can further test the fuel pump by applying direct power to the fuel pump relay using jumper wires. If the fuel pump now works and runs smoothly with the power applied directly, then the problem is at the relay or its wiring. A good example could be when the relay fails to engage at times, which can be noticed by hooking up the multimeter and observing fluctuations in the power supply.
Some relays fail and can have the fuel pump work sometimes, resulting in erratic delivery of fuel to the car and therefore performance. Indeed, some reports were given for the 2017 Chevrolet Malibu, wherein this has been known to cause the stalling of the fuel pump. As observed, the car did not always start; it was determined to be an issue with a faulty relay after investigation.
Testing the fuel pump relay for faults involves checking the fuse, using a multimeter for continuity, and direct power supply to the pump. Regular maintenance of the Fuel Pump relay and the fuel system will go a long way in ensuring the proper performance of the engine and preventing costly breakdowns.