I just bought an 83' F 100 that has been sitting for a couple of years. I was told that only one tank works but not sure which one. I need to find out how to know which one it is. There is no switch on the dash. The wiring diagram looks like it works automatically off the sending units. I have found the solonoid but not the switch. Does any one know where to find the switch? And how much do they cost?


thanks/deven

 

How I would quickly find the problem.

If it has a carb (which it should), take the line off and put it into a can. Crank the engine (we want to crank enough for tablespoons, not gallons .

Got fuel? Good, if not check pump system or filter.

Crimp a fuel hose from a tank.
Crank. Got fuel? Good.

Undo crimp, go crimp the other tank's hose.

No fuel. 1st tank is has the problem.

Reverse the logic to check second tank first to double check the check before tearing anything apart.

Since you want to replace all the fuel lines anyway on a 83 truck, I would feel free to use straight jaw vise grips for the test. I find they work best for this type of thing and are easy to use underneath the truck in a confined space.