Fuel Line Problem

[barebones]

1990 F350 460 Lariat LTX 2WD Dually 2 Tanks

The old Return-to-the-wrong-tank issue.

I really don't want to remove the bed to change the pumps. I already did it on an F150 last summer. Even then I thought of a better solution, the pumps were still good - 35# at the rail

While I never took an old pump apart, discussions seems to help one to imagine the workings of the innards. There is a pressure operated shuttle valve that opens the return line to the tank. When the pump runs fuel pressure opens the valve. When pump is off, a spring closes valve! Maybe, it's only a broken spring!

There is a single return line that goes to both tanks. Were I to split the return line and use two electric on/off fuel valves wired to the tank selector switch. They'll replace the function of the shuttles in the pumps.

Looking under the truck, the modification appears to have easy accessibility to place the switches and change the return lines.

Has anyone tried this? Does anyone have a different simple solution?
Any suggestion on the on/off fuel switches.

b

 

[Fellro]

The canister looking thing on the frame rail is the factory device for determining which tank it goes to. I personally don't know of an aftermarket solution to it. What you describe is actually similar to the switch that is common on diesels of that age, yet difficult to find. Some of the aftermarket tank switches would be a way to give positive control on such a situation. Otherwise a passive inline check valve would do similar.

 

[barebones]

I do know what you're talking about; however surprise, surprise, my system on the F350 is exactly the same as what I have on my '93 F150! The lines from the tanks to the rail are joined with a 'Y' connector just before the Filter, and the lines returning from the rail to the tanks splits with a 'Y' connector at the mid-ship tank. This arrangement relies on a valve integral to the pump to accept or deny fuel return. I discovered this when I was researching my F150 tank return problem. The use of a shuttle valve and it's operation is my notion.

I have no idea how Ford policies regard mid year production changes or experiments.

This truck is a 1990 F350 Lariat XLT, Extended Cab, 460, E4OD, 2WD, dually with 89K on the speedo. It spent the majority of its life in Atlanta, Georgia. It moved to Montana a few years ago and was never driven in the winter. It has never been in an accident, The body, except for the plastic, left rear fender (came with replacement), is mechanically immaculate. No dings, dents or scratches or rust. The interior looks almost factory new, but the Georgia sun and lack of protective coating has caused the exterior red paint to lose its luster. The undercarriage, considering its age, seems exceptionally clean and unmolested.

I did order a fuel tank selector (from carburetor days), and I wonder about pressure, I'll install it at first opportunity. I was originally thinking of using two of more robust switches. It'll be easy to restore if a problem arises.

I'm still open to any replies and suggestions.
Thanks for the reply,
b

 

[barebones]

Update! Major issue.

I just happened to think: High pressure hose and connectors. I'll have to mortgage my house!

I guess I must change the pumps. I'm going to need a strong branch somewhere to hang my bed. NAPA says it'll guarantee pumps fits.

It's shame that the pumps are serviceable, yet the internals are so delicate they prematurely fail. This certainly simplifies assembly and lessens initial costs, but intensifies repair time and fees.

b

 

[Fellro]

You can drop them out the bottom too. My bed bolts are so rusty it is the only way I am able to do it. The front one I was able to get out without removing the tank, but it can be a trick getting the ring out and in.