Hi, First post. Hope someone can help. I picked up an 83 250 with a 460 and dual tanks. Both tanks read full all the time and neither pump works. I have tried to find a schematic with no luck. I bought a Haynes, a Chiltons and the Ford shop manual for chassis and electrical but none of them show the tank selector valve that I have which has 4 lines in, 2 lines out and a 5 wire connector. If you know where I could find one I would appreciate the information.
Thanks RDM

 

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The haynes manual has it, look for the FORD Trucks 80-86 version. It is in the fuel chapter I think 7 and it is in the wire diagrams in the back. Your 6 line switch valve is just like mine, a Supply line and a return line for each tank, (4 in lines) and one supply line and one return line (2 out lines to front of truck). Your 5 wires are;1) a common ground that goes to both tanks, 2) An orange and a blue (the pumps if memory serves me) 3) A brown and red/white for the sending units. The colors change a little between years, but thats basically how they go. When you switch from one tank to the other you are simply switching polarity (+/-). If you are still having the problem shoot me an e-mail and I'll get my book back out and try to help you out. My fuel system was my single biggest headache, (and still isn't perfect) but I have gone through and rewired replaced rebuilt the entire truck to include this so if I can help I will, I know how frustrating it can be.