I have a 1988 Ford F150 with Dual Tanks. I have seen tons of posts concerning the issue I have, which is.... The truck always pulls gas from the front. IF I switch to the rear it is still pulling from the front. However the return line is filling up the rear tank.

I removed the switch from the dash and noticed that it was warped. So I let the truck run with the switch in both the front and rear setting to see what was going on. When I set it to the rear tank the switch begins heating up until it is to hot too touch. I tried replacing this switch didn't fix the problem. Then I repleaced the 6-port Selector Valve. Do I just need to replace the rear fuel pump or what? I can't figure out why the switch itself is getting phyiscially hot....

 

You'll probably need to get a response from one of the guys who knows electrical troubleshooting better than I do.

I can post wiring diagrams of the tank switch area, if you would like, once I get home this evening. Interested?

 

I am definitely interested. I have the diagram in the Haynes manual which is very simplified. I have purchased a new relay and a new fuel pump.

 

I apologize for not checking back in last night as I said I would. I'll do my best to get you some diagrams this evening.

If I remember correctly (that's a big "if" though), on my 1994 F-150, you have:[list=1][*]Battery[*]Inertia Switch[*]Fuel Tank Selector Switch[*]Fuel Pump[/list=1]

There may be other stuff in there, but I believe these are the major components. Have you done any looking for shorts? The heating up thing is interesting. Wouldn't that seem to indicate too much juice flowing through the switch? If so, I would spend time looking at the wiring harness from the switch to the fuel pump. Another thing, shouldn't some fuse be burning out before your switch starts to melt? My tank selector switch went bad on my 94 about 2 months ago and I seem to recall a fuse or two being involved in the circuit. (After replacing the switch, all was well with my truck.)

I just don't know, though. I wish I knew more about such things. Like I said, I'll try to get you those wiring diagrams tonight.