I want to abandon my rear tank on my 86' f350 and bypass the tank switch on the frame (cause its not working). I can figure out how to direct plumb frame hoses to tank, but I'm having trouble figuring out which wires I need to use in the 5-wire electrical harness to send tank sending unit signal to dash gauge. The wire plug into the tank switch has 5 wires:

yellow with turquoise (smaller diameter)
yellow with white (smaller diameter)
purple with yellow (thicker)
red (thicker)
brown with white (thicker)

I've been all over the interweb and cannot find an easy schematic that shows/tells wire colors. I'm understanding that the yellow with white stripe is the signal wire from sending unit to gauge. But sending unit has 2 contacts. Do I just use the thinner yellow wires and splice them directly from sending unit to frame wire loom? Or do I need a ground and signal wire?

Thanks in advance!!

Chris

 

This thread should have the info you need.

https://www.oilburners.net/threads/f.../#post-1099296


Charlie

 

Thanks Charlie. But do I connect wire #4 to one sending unit connector and then wire #5 to other sending unit connector? That simple?

 

I also recently changed the fuel tanks out to manual control valves, and had to figure this gauge sending question myself.

It is very easy actually, it's just that there is confusing looking, and little information about how to wire it up.

This being the only occasion that I ever touched that accursed FSV, and had a pleasant time of it.

Such a horrible spot to access and work on, but anyway, I deleted it.

But as you know, or have found out, that motor the slides the fuel selector port also slides the contact points for the gauge sender up and down, so if the gears are jammed, then the tank selector switch also won't work properly.

Anyways, the wiring is super simple. Looking at the attached wiring diagram will explain how it works.

Pull the electrical plug out of the FSV, and look at it like the shape of the letter D.

There are 5 pins, starting with 1 at the bottom and 5 on top.

Pin 4 is the output wire to the fuel gauge.

To pull your reading off the front fuel tank, simply insert a jumper wire between terminals 3 and 4.

To pull your reading off the rear fuel tank, simply insert a jumper wire between terminals 4 and 5.

It's been 2 days, and you've probably already solved the problem, but yes, it really is that simple.

 

Thanks for info Leroy!!! I did already figure it out. The yellow with white stripe goes to gauge. My FSV was jammed and nothing was working, so I connected the fuel tank sending unit wire (blue with yellow??) to the yellow with white and it works like it should. I bypassed the FSV completely and just running off the front tank now.

Thanks!!

 

Just to say, the brown w wht tracer is the signal wire to the selector valve (dual tank).