Hello all. I have a 1984 E350 Holiday Rambler Ambassador motorhome with dual tanks, a 460, and a 750 cfm Holley. My fuel pumps currently only work when cranking. My oil pressure switch is jumped. I would like to upgrade my current system but I need help understanding it.

I bought a Carter fuel frame mount fuel pump, and want to run this one pump for my system. It should be adequate. Can I use the stock switching valve? From what I understand, pressure from the tank is needed to operate the valve. What are the 5 wires that go to the tank valve switch for? Also, where is the location of the inertia switch, fuel pump relay, and fuel pump cutoff relay? I do not trust all the jazz going on in this system.

 

Hi brendo613,
here might be a great place to start:
https://www.ford-trucks.com/forums/1...lem-460-a.html

See if that helps and post back. jim

 

Hi Jim, thank you for that link. I had found that the other day and read through it but I still have some confusion. I want to upgrade my current pump but retain use of the fuel gauges. I need to cut power to the stock pumps but I'm not sure where power goes to them from. Is the source the relay on the driver's side inner fender? Also, what do the wires on the tank switching valve do? There are 5. Thank you

 

Pins 3, and 5 are the fuel sender inputs, pin 4 sends the selected tank sender to the gauge. To run the frame mounted pump all the time, you could remove the selector relay and use the PK/BK wire going to the relay.

Two questions I have are how are you going to modify the fuel pick up in the tanks, and is the frame mounted pump going to supply too much pressure to a carb-ed system? Subford did the original diagram and may see the post to comment. jim



Single frame mounted pump to replace in tank pumps.

 

Thank you very much for the detailed response! I had to drain the tanks from old gas and there is sufficient fuel flow through the in-tank pickup even when using an external pump. The new pump I have has a built-in regulator. It's a Carter pump designed for carburetor equipped systems, 4-8 psi if I recall correctly. Weather permitting, this should be a successful weekend endeavor.

I was planning on using only the oil pressure switch as a trigger for a separate relay powering the new pump. Thank you much for your help!

 

I replaced the mechanical fuel pump on my IDI with a frame mounted electric. I am not familiar with your gasser setup, but if it only pumps while cranking then i would assume it is a mechanical pump mounted on the engine. If this is true then you do not need to touch the selector valve wiring or drop the tanks. Just mount the electric pump on the engine side of the selector valve. Run a mount a 12v relay with a constant 12v and a 12v signal from a circuit that is only hot with the key in the start/run position. Run a new duel line to the carb.Remove the mechanical pump and block off the opening.

 

Hello all, turns out the module fuse blew due to a short in the emissions control circuit. Apparently they share this fuse! Now the chassis runs the pumps with engine on as well as during crank.

Next step is to locate the inertia switch.

 

MOST of the time, it is under the dash on the passenger side kick panel, in a cutout at the top.

Cargo vans it is under the dash, driver's side, to the right of the steering column.

 

Fantastic! Thank you so much for that. Some people have just the right diagrams and technical writeups. Amazing

 

Shhh, don't tell anybody, it is in the Owner's manual here:
Owner Manuals | fleet.ford.com

I just cut/pasted 2 pages together in one graphic. I used to teach owner's manuals but on jet planes, not vans.
jim