I have a 1986 F150 4x4 302 EFI motor with dual tanks. I understand it has three electric pumps 1 in each tank (low pressure units?) and one on the frame rail (high pressure ?).

I am contemplating a switch to carb if I cannot get the EFI to run reliably. So, I am trying to find out the running pressure on the two in tank pumps and whether they could be used to feed a carb.

I know that the transfer valve is an issue too. I am wondering if anyone has tried this and how it turned out.



Thanks in advance

Chris

 

switching to carb from EFI isn't going to solve your fuel delivery problem if that is the problem. do both tanks work? do you have an issues with fuel being directed from one tank to the other? have you changed the fuel filter?

 

I want to say the low pressure pumps are 9-10 psi, but I have no official source for that. If that's the case, it's still too high for a carb. Also a carb system "dead heads", meaning when the carb doesn't need any fuel, it stops the flow. All 3 pumps in your system are not designed to dead head, with no relief in the pump if it happened.

There are plenty of cheap electric pumps on the market though that would work, and are designed for a carbed system. You would just have to mount it on the frame somewhere, and take the pumps out of the tanks.

 

I am going to check to tank pumps first to see if they are working. I bypassed the relay and got the front high pressure pump to come on but could not hear either tank pump running. There was no gas making it to the front pump, so I think the problem is either in the in-tank pumps or the wiring. I have found the wiring schematic and will see if I can figure it out.

Just wanted to know if the EFI in-tank pump pressures were in the range of a carb'ed fuel pump. If they are 9-10 psi then you could probably use a regulator to bring it down to 5-6 psi and run a return to the tank using the factory steel line.

I would prefer to keep the EFI, but I do not want to chase all sorts of issues with a 25 year old system. Also that Dual Function Reservoir is a snake's nest. What a piece of art. Man, I hope it is working OK, but if not I may just run on one tank.

Thanks

Chris