Hi everyone,
I have had dual fuel tank issues in my 86 f150 with the 5.0 efi engine for over two years now. I need a permanent fix. I am on my third fuel selector valve and now it’s failing again after less than a year. I would like to change out the pressure activated one with one that is electrically operated.
First does anyone know if I can replace the older one with a newer model and if so how do I wire in the electrical connector. I see a electric valve and connector for sale on line. Also are there any fuel line connections issues?
Thanks for information you can provide.

 

Ford used a variation of the fuel reservoir you are are having trouble with in EFI trucks from 1985 thru the end of small blocks in trucks. Sorry that your replacements were not up to snuff. A possible easy, inexpensive fix could be to buy a four port reservoir for a single tank truck. $70 shipped. Eliminate one tank and the moving parts, diaphragm & shuttle valves inside the six port you have now. No fuel passage to diaphragm o-ring to swell shut. You should still easily have a 275 mile range at average f150 fuel economy.

I would be grateful if you could describe how your valves are failing. Always looking to learn something new about this fuel system.

 

Thanks for your reply.
When I bought the truck three years ago It would only run on the rear tank. I had the front tank and tank fuel pump replaced. It still would only run on the rear tank. I found a new old stock selector valve and had it installed. It worked at first but then the high pressure in-line pump started making a groaning noise. Later it pumped all the fuel from the front tank into the rear tank and over flowed onto the ground. Then I found a new remanufactured one. That one was working when the high pressure inline pump failed. After replacing that it worked for the next two times I drove it. Now today when I drove it the new in-line pump is making groaning sounds again and the front tank gage reads empty when I just put at least 8 gallons in both tanks. It is stalling out when using the front tank but runs fine with the rear tank except for the fuel pump noise and the tank reading empty.
I’m really getting frustrated with this and maybe I should take your advice and just go with one tank. I would really like to find a reliable solution to the two tank issue though.
Thanks again for your advice.

 

A common issue with the six port reservoir/selector is the tiny passage from the low pressure (tank side) inlet to the top of the diaphragm. The small o-ring in this passage swells and blocks the fuel flow into and out of the chamber above the diaphragm. If this chamber is full of fuel and the fuel cannot flow back out when the front tank is selected and fuel from that tank tries to push back up, the valve gets stuck. Usually somewhere between and fuel then flows from one tank into the other. If the replacement units were assembled with a less than great o-ring, it is likely it may be swollen to the point of obstructing the fuel signal passage. Another possibility is the anti siphon (check) valve from one of the tanks (the one that overflowed) have fallen out. These are the two covered ports in the roof of the filter section. You can see by looking if they are both intact or if one is rolling around in the bottom of the reservoir (screw on cap).

There is a site on the web where a Bronco guy goes into detail as he refurbishes a six port. I'll try to find it when I get a chance.

The HP pump noise is probably cavitation which is usually linked to fuel starvation. Normally it takes up to 5psi inside the reservoir from the tank pump to push fuel back through the return line.

 

A wealth of information on both single and dual function reservoirs here. Link to dual function reservoir starts HERE. Preceded by single function type.

 

If you went to a single tank operation you could still keep your second tank and only use it when you needed more range by using a fuel transfer pump. Seems those are pretty cheap and run off the cig lighter for power. Something I've thought of doing if my valve goes bad. I'm diesel so I don't have the same mothballing and fuel stability issues you do. But maybe when the second tank is not in use try to pump it out dry. Use seafoam, or stabilizers or maybe a squirt of diesel?