Yes, it can drain the car battery if the fuel pump relay works defectively. A defective fuel pump relay may keep the fuel pump running even when the vehicle is turned off. It only operates when the ignition is turned to an “on” or “run” position and pulls power directly from the battery. A bad relay may not let go and can cause the fuel pump to run constantly, which will flatten the battery in a few hours. Most fuel pumps use between 6 and 10 amps, and if the relay is allowing the pump to run, then it can flatten a completely charged battery-which typically has a capacity of about 48 amp-hours-much faster than its estimated life.
The problem is most times caused by electrical faults within the relay, mostly as a result of internal contact failure that does not allow the relay to break the circuit. This could be due to corrosion, damage by heat, or even mechanical wear; this is often the case with high-mileage vehicles greater than 100,000 miles. Given symptoms may include, but are not limited to, hot relay, continuously operating fuel pump, and fast-draining battery, even after short idle periods.
Drivers may also experience problems in turning the vehicle over. This is because a dead battery usually cannot provide the requisite voltage for the starter motor. If the car has been sitting for some time and refuses to start, it will be a good idea to check the fuel pump relay for failure. Many mechanics will suggest that one should replace relays every 100,000 miles or anytime that overheating or heavy wear is evident.
Another contributing factor is improper wiring, whereby a short circuit may be caused to keep the relay engaged when it is not supposed to be so. In most cases, such wiring problems tend to increase the resistance in the electrical circuit and thus put more stress on the battery and other electrical parts. Proper wire maintenance and regular check-ups should help prevent a lot of these mishaps that can lead to draining of batteries.
As Henry Ford, the great innovator in the automobile world, once said, “Quality means doing it right when no one is looking.” Taking the proper steps in maintaining the Fuel Pump relay ensures the longevity of the battery life and the general working state of the vehicle. For all your fuel pump relays and associated products, visit Fuel Pump.