Just picked up a '86 F250 with a 460 five speed. It has been sitting a while and the fuel pumps are jacked up. Should I just bite the bullet and buy all three new ones or put an electric inline one in?

 

Does it have 3? If it is the carburetor 460 it probably only has one.

 

Do you have a plan for using a aftermarket pump? You will still have to remove and modify the sending units for the different setup.

 

It has a pump in each tank and an inline one.

 

Your truck is not original. They did not offer the 5 speed in 86. Did you just buy this truck? Do you know the history of it? The only trucks in these years that had 3 pumps were the 5.0 efi trucks. The 460's only came with a 4 speed manual, and only had one electric pump in each tank, or a mechanical pump on the engine with a return line.

 

Sorry, my bad it is a four speed.

 

The pump thing is still true. Are you sure you are not thinking the switching valve is a pump?

 

Maybe. A guy gave me a couple pumps earlier, can I just change one? I couldn't get both to run. And they look a lot different in size, can you tell me which one goes where.

 

Before you start replacing things have you figured out why the existing pumps don't run? Are they getting any power?

Maybe you've done a bunch of tests already...but if you haven't you might start by supplying power to the fuel pump bypass wire to see if you can get a pump running that way.

The fuel pump bypass wire is wired directly to your fuel pump. It is (should be) attached to one of the small terminals of your starter solenoid. I believe it's attached to the I terminal and the S terminal is your starter signal wire that activates your starter when you hit the key.

Anyway, (MAKE SURE THE TRUCK IS NOT IN GEAR!!! If you jump the wrong wire you could activate the starter and the truck could jump! Not good if you're standing it front of it!!!) you can jump a wire from the positive battery terminal to your fuel pump bypass and listen to see if a pump runs. Just don't leave it hooked up that way very long or you could fry some wiring.

If you do get a pump running via the bypass your problem may be in the main fuel pump power supply circuit.

 

Will this eliminate the fuel pump relay?

 

It will bypass the inertia switch, fuel pump relay, and oil pressure switch circuit, but not the tank selector relay...

Here's a look at it. No point in replacing in tank pumps before sorting out the power supply.

 

A question on this I have my self is how many wires go's to the tank? I got four wires. dose that means that I have in tank pumps? I got a 86 with a 460 automatic 4x4.

 

If there's a question about weather you have electric in tank pumps you might look on the driver's side of the block toward the front to see if you have a mechanical pump mounted there...

I've not pulled a fuel tank pump or sender so I don't have any 1st hand experience. however:

Looking at the diagram, if you have in tank pumps you should have at least three wires; power, ground and gauge, and then some fuel hoses, perhaps a supply line, vent line, and a return? Hopefully someone who's been there and done that will chime in.

 

It didn't have the original motor when I got it. The motor had a mechanical pump on it. But it has always had some short of fuel problem.