My Uncle's Truck

You really have no luck with fuel pumps. It must be a family affair; your car and now your uncles' truck. Both pumps could have the same fuse and positive 12 volts?

A lot of fuel pumps you hear running as soon you turn the ignition switch. My friend changed 3 fuel pumps in a week and at the end the pipe in the fuel tank got periodically clogged by a piece of duct tape that had been deposited in the tank.

He has 3 pumps now for a ford pickup. All paid for and still good.

I forgot: fuel pumps have another common thing: FUEL , is there any left?

Success

The switch for changing from one tank to the other. Turns one pump on and the other off. Fuse to this switch. That's if it does have two fuel pumps.

How do you know that the relay is good? Hearing a click does not mean that it is providing sufficient voltage and current to the pump. If the voltage at the fuel pump reads within 5% of battery voltage, check that the fuel pump produces sufficient pressure and volume of fuel.

This is troubleshooting 101! You first verify if everything is good for a component to work, then you test if the component actually does work. If you go sequentially from where things do work to where things don't you'll find the problem. But don't just assume when a component appears to not be working that replacing it with a new part will solve your problem. There maybe something else causing that part fail.

This poor guy has an enemy. I think the enemy enjoys a good laugh by putting plastic sandwich bags in his gas tank.

BS. If you ain't got a witness or photos, I'm denying it.

'...both fuel pumps going out at the same time...' Says who? The first may have died long before, and it's partner possibly died from loneliness. Check voltage at every pump's connector. Dual tank with separate pumps is a very bad solution unless you make sure NONE will get dry before the other (which is technically challenging since pumps can't be a 100% match). S.M.

In any event your iginition should turn the fuel pump on. So, when it fails your likely fixes could be the wire, as well as your ignition. The alternative to this is a sensor or the lines might be blocking the return cycle for the rail, that the fuel injectors are connected too.

There is not to much left you can check here the fuel pumps turn on ? you checked the relays Fuel Filter perhaps

There may be a safety roll-over switch below the passenger side dash. My daughter's ford explorer has one there. Generally you just press the red button on the bottom of it to re-set it. It's possible for this to trip just hitting a bump when you go off-road and park. It would feed power to either pump and trip either one off.

If you are not getting voltage to the pump, older Fords have an impact switch under the dash on the passenger side that shuts off the fuel pumps in an accident. It is manual reset. Newer Fords use an automatic reset. That involves a relay that must be good as well as the impact switch being in the closed position. -- JHF

First I would be sure you are getting fuel to the pump. Remove the feed line to the pump and pop the gas cap off, you should have a gravity flow, as long as there are no debris blocking flow. Good flow reconnect the line and remove the pumps electrical harness, put your volt meter on and turn on the key. 12 V yes and no pumping..... the pump is bad. If no voltage is present head to the fuse box. Fuse is good.......put your meter on the input to the fuse and again turn on your ignition key.

If there is no power there...... well heck it could be a bad ignition key not starting either pump.

What year, model, and engine is the truck? What fuel injection type? Most fuel pumps die slowly giving you some advanced notice. Spray some carb. cleaner down the intake to see if it will run for a few seconds. Do a wiggle test. Press the shrader valve on the fuel rail to check for fuel. Beat on the fuel tanks with a hammer. works on GM's when fuel pumps get stuck. Some efi fords you can short to ground a terminal at the DLC connector. Dual tank Fords can be a pain. If the pressure was just low they will flood and then won't start when is everything good. Check the plugs. Get the book if all else fails or better, check the book first. Good luck.

Lyn-Door industries has a fuel pump relay bypass system that works well on carborated engines. It might be possible to rewire the bypass system to work on your fuel injected truck. Because it has duel fuel tanks, you would of course need two of them. Good luck.

If Im not mistaken some trucks with duel tanks (1987 Ford Ranger 4x4 I believe)have 3 fuel pumps.........2 in the tanks which are low pressure and 1 in-line which is high pressure, maybe your high pressure one is at fault. ........Rescue