The most common symptom of an electrical issue with the fuel pump is a fuel pump that is not running with the key off; in this case, more often than not it turns out to be a problem with the fuel pump relay. The fuel pump relay controls the distribution of power to the fuel pump, and when it malfunctions while in the "on" position, it will continue supplying power to the pump even after you have switched off the engine. It will keep the fuel pump on, which can drain your battery and stresses the fuel pump who has a life span. Operation of the fuel pump for a long time without rest will make up 10-20% reduction in efficiency due to this conduct as compared with when operating through a properly working relay.
From the wiring, there could also be a short circuit. This connection results from the fuel pump wiring harness wearing or getting damaged, which creates a direct route to the power source and bypasses the ignition switch. Exposed wires, corrosion or bad connections can lead to electrical shorts. Automotive technicians report that electrical issues like these cause around 15 percent of all cases where a fuel pump keeps running.
Sometimes the problem is a bad ignition switch. The ignition switch provides power to multiple systems including the fuel pump. The pump may continue running if it does not shut off the power when the key is removed. The issue can also spread to other electrical systems in the vehicle as well, resulting in a host of problems.
Noteworthy examples are vehicle recalls resulting from fuel pumps working when the engine is not running. In 2018, for instance, Nissan had to recall hundreds of thousands of cars all over the world owing to a defect in the fuel pump relay system which made it so that even when the engine was off and car parked, the pump would still operate. It shows how a seemingly simple electric part can render the car less functional.
Remember what Henry Ford said, “Nothing is particularly hard if you divide it into small jobs”. Preventing further repairs associated with the cost of constant fuel pump. The relay can be checked, the wiring inspected, and even the ignition switch verified in order to fix it.
More informations on how to diagnose and fix a fuel pump issues, visit Fuel Pump.