Hi all,
Im helping a friend of mine try to fix his truck. its a 1987 Ford F-250 with dual tanks. The front tank wont work even after putting in 3 different used sending units and 1 new sending unit. And the rear tank the guage will read full when there is any gas in it and empty when its starting to run out.
Would this be a wiring issue?
I do have a multimeter but I am not sure on how to hook it up or use it to help us find the problem.
His truck has the 5 wire? plugs for the sending unit. what are each of the wires for?
Any help would be greatly appereciated!!
Thanks[/align]

 

check the swithing valve its located on the left frame rail just behide drivers seat

 

also check fuel pump relay located on left inner fender and inertia switch located under dash right above where clutch pedal should be on firewall

 

we alreadt tried that,
would anyone else know?????

 

i tried all that to on my 87 f-350 crew cab and it wold run about 200 feet and run out of fuel so i finally pulled the units out of both tanks and they were new at 200 bucks each pulled the pumps off of them took a piece of tubing and rubber fuel line and extended the pickup to the right depth bought an ac fuel pump and canister filter hooked the fuel pump up to the hot wire coming from the inertia switch install filter between tanks and fuel pump that finally solved all my problems except rear gauge doesn't work all this cost me about a 1000 bucks after new tank units new switching valve new relay and a month of headaches good luck

 

I had the same issues in my 89 F350, but some different symptoms. My mechanic laughed at me and said he had the same issues with his truck and his brothers. Told me he doesn't even attempt to correct these issues anymore....... I am just guessing on how much fuel is left now and thankful for that second tank when it goes dry unannounced......Good luck