OK, I have an 86 F150, EFI, when I got it it needed some serious work. I changed the fuel pump in the rear tank and the one on the frame rail. Now I can't seem to get it to bleed out. I have power at both pumps and I know they are pumping. It also has a new filter. I just can't get it to get a prime. Any help would be appreciated.

 

There is no need for a fuel injection vehicle to "prime" as you would think of this on a conventional carbed vehicle. On efi, the fuel recirculates, pumping from the rear to the fuel rail, and then returning to the fuel tank by going through the pressure regulator mounted on the fuel rail at the engine. So any air in the system is pretty much gone after a couple of tries at starting.

Are you getting fuel up front? One problem you may have is no fuel pressure test port. Some of the early vehicles did not have a port where you can test for fuel(looks like a tire valve on the fuel rail). You might have to pull a line off to see if you have fuel. Be careful, this system runs around 40 psi pressure.

 

Welcome to the forum first off!!!

when you replaced the LP pump in the tank...did you clean out the tank? There is often dirt and grime built up in there that can clog the pump.

Have you checked the lines between the 2 pumps to make sure they are clear and in good condition...no cracks and not colapsing?

You can try disconnecting the line between the pumps and see if you are getting fuel to the HP pump when the LP is running. Run the line to a gas can or something so it's not just going everywhere. This would isolate it to the LP pump if not.

 

Welcome to FTE! Do you have dual tanks? If so, the valve that determines which tank to draw from may be stuck drawing from the wrong tank. Those valves are finicky and I've seen them do very strange things - like draw from one tank and return to the other.

If you do have two tanks you can bypass that valve by buying a fuel line splice kit from a parts store. You will have to bypass both the supply and the return.

 

It was the tank selector valve. I bypassed it and she is running beautifully. Thanks for all the help. I think I am going to install a 38 gallon tank in the rear, do any of you know if I have to replace the sending unit or can I just modify the existing one?

 

Is the 38 gallon a stock Ford tank?

Ah Gary...where's those catalog pages??

 

Glad to help. Those valves are fraught with problems. In the 70's Ford used a manual valve for the tank and a switch on the dash for the gauge, and they worked fine. But, that was apparently too complicated for some people so they went to an electric valve controlled by the same switch that controlled the gauge. Worked pretty good, but you had to keep track of what was in the other tank because if it was dry you ran out before the gauge told you it was dry. In the latter part of the 80's they went one step further and put in a valve controlled by the in-tank pump's pressure. Worked ok when new, but when they fail they do strange things that defy all logic.

Attached are the master parts catalog pages for fuel tanks as well as sending units. We would have to ask so many questions about your truck to figure out which tank you have and which one you are thinking of installing that we'd get done next year. This way you can figure out which ones, and then go down to the sending unit pages and figure out which one you'll need.

Yes, kinda a pain! We need a sticky on fuel tanks and associated sending units.

 

Thanks, I had found an after market tank on rockauto.com. I am pretty sure I am going to have to extend the bracket for the pump and sending unit. I haven't found one you can buy. Thanks for the parts info. I need to decide which way I want to go with the truck, either way that silly valve is gone.

 

It is for a Bronco.

 

The aftermarket 38 gallon comes with instructions for modifying the existing sender unit.
38 Gal. Steel Tank,Pick-Up

Bronco Graveyard also shows some 45 gallon tanks with sending units included.

Note you must relocate the spare tire somewhere else. And If you have 4x4 then not sure if you can use the skid plates?