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What is a fuel pump relay?
The fuel pump relay is like an automotive fuse and supplies electricity to the fuel pump. The fuel pump itself takes a lot of power and is working quite often, so it needs some help from the fuel pump relay to regulate itself and not get too hot.
A working fuel pump is one of a few things that decided whether or not the engine works – as the fuel pump relay is vital to the fuel pump for longer trips.
Since we have discussed the importance of the fuel pump relay, we also have to say that jumping your fuel pump relay should only be temporary until you can get your truck to a place where you can repair the fuel pump relay.
Symptoms of fuel pump replay issues
Your vehicle might not start for a variety of reasons. Are you sure the issue is the fuel pump relay? The vehicle not starting could also be a matter of the starter not working or having a dead battery. Other symptoms that are more obvious while driving like checking engine lights, having the vehicle slow down or stall while driving, and rough acceleration.
If the fuel pump is working, you should also hear it starting if you are outside of the vehicle while attempting to start the vehicle.
Jumping your fuel pump relay with jumper cables
The first, and sometimes the easiest option, is to just disconnect your fuel pump relay from the battery temporarily, then jump-start the vehicle. The fuel pump relay box should be beside the fuse box or next to the battery terminals. You'll probably find that the relay box is well labeled as long as it isn't covered in grease and dirt.
Once you've located the fuel pump relay, you'll want to disconnect the battery terminals from it. This might require a wrench or ratchet to easily and safely remove the terminals.
You can then connect your jumper cables to the battery like you normally would. Start by connecting the red end of the jumper cables to the red battery terminal, then the black to the black – which is sometimes blue. Be careful when doing this. Do not touch the terminals with metal in your hands.
The next step is the easy part: Turn on the engine. You'll be looking for a green indicator for your fuel meter. Not all trucks have these, but generally looking for engine lights to come on anyway, to indicate potential problems.
The alternate method: Wire cable
This method is similar to jumper cables, with one minor difference: You'll need a 5 inch copper wire with some of the insulation stripped off both ends. After finding the fuel pump relay, push one into the pin slot near the high left corner of the pump relay. Insert the other end into the pin slot in the bottom right. This works in a pinch, though we think many of you will have jumper cables anyway.
What to watch out for when jumping your fuel pump relay
First, when you do start the truck and look for the green light in your fuel display or engine light – this could change. The truck might not recognize the problem right away and tell you everything is fine, then realize later that there is a problem. Considering that there is a problem – the truck is not wrong! It may also shut off again as a result.
Our best advice is to let the truck sit while running for a little while to see if any problems pop up, then try going.
What should I do next?
The honest answer here is just to be careful. While you might be OK with the idea of jumping your fuel pump relay every time you get into the car for a while to avoid replacing it, that's not a real good idea. Ideally, your next trip should be to a mechanic or to an auto parts store where you can replace the fuel pump relay.
While the vehicle can run without the fuel pump relay for a while, you can also consider the relay a safety device. You could burn out the fuel pump while driving and cause the engine to stall. You could also get into an accident and the fuel pump might not turn off because it doesn't know to without the relay.
Letting the vehicle run too long, or too hot, can cause permanent damage to your fuel pump. Considering that the initial problem is a relatively easy fuel pump relay, you don't want to risk another expensive or time-consuming repair in the event that you run your fuel pump too hot.
What causes fuel pump relay failure?
The answer is usually just age. Sometimes electronics just stop working because they are old. The fuel pump relay is fairly well protected and encased with plastic, so it isn't likely to suffer damage.
Can I fix a fuel pump relay?
As with electronics these days, you are usually better off buying a new fuel pump relay instead of trying to fix what is there. If you have lots of experience with vehicles, electronics, and pump relays, be our guest – but replacing the part is usually the easiest.
Can I check the relay with a multimeter?
You sure can. Most people do not have a multimeter handy, but you can certainly check to see if the resistance is within specifications if you have one. Note that this is especially handy because it will readily rule your fuel pump relay in or out as the problem.
About The Author
I've spent many years selling cars, working with auto detailers, mechanics, dealership service teams, quoting and researching car insurance, modding my own cars, and much more.Read More About Charles Redding