I have a 1983 F150 2wd Single cab long bed 5.0 V8 2bbl AOD transmission. The truck has dual fuel tanks.The fuel gauge doesn't work for the front tank and the rear tank. I have used a test light and the switch in the dash is getting power and the selector valve on the frame has power, but the gauge still doesnt work. Is there a ground wire that I am not finding or could it be that the sending units need to come out and get cleaned up then reinstalled?

 

Bad rear sending unit.

 

Should i check the front tank sending unit?

 

Why? If the gauge works for the front tank, it's fine.

 

Should replacing the sending unit in the rear tank fix the problem with the gauge for the front and rear tank?

 

What problem are you having with the front tank? You said it was only on the rear that it didn't work. The ground for the gauge is through the level sender, so if the sender is bad, you get an open circuit. On pre-'87, that makes the needle fall to E.

If the circuit goes thru the valve (I don't think it does, but I'm not familiar with pre-'87 dual tanks), then yes: that could also be the source of the open circuit.

 

I made i correction on my first post. Both fuel tanks aren't reading on the fuel gauge.

 

Did both senders stop reading tank level at the same exact time or was it first one then at some later date the other?

If they both quit simultaneously there is not a problem with the sending units, it is somewhere in the wiring

I don't know squat about how the '83 is supposed to work but you need to get a wiring diagram and start tracing and checking continuity.

 

I just recently got this truck and the gauge hasn't worked at all since I got the truck.

 

I would still bet on it not being the senders. They fail occasionally, everything does, but the odds of them both going out are pretty slim

 

One of the senders could have gone out LONG before the other - he only just got the truck. And those old wire-wrapped pots weren't that reliable to begin with. I still think it's the senders, but it's easy enough to find out: withOUT disconnecting anything, splice (pierce) into the level sender wire on each tank, and ground it. Then turn the key on, watch the gauge for ~10 sec, then switch tanks & watch it.

 

The fuel gage in my truck stopped working some years ago. As my mileage has not varied since new, I merely keep track of when I filled last and save myself the hassle of messing with either fuel tank. I've replaced the pump on the frame rail and the switch for the tanks works just fine.
1989 F-150, 4.9L/5spd.

 

Your '89 uses the newer style level sender, and your gauge works totally differently from pre-'87.

 

Ok, I think I got the fuel gauge to work. Now I am now trying to figure out how some of the vaccum lines for the fuel system hook up. There is a metal line that goes from the fuel tank up to the engine bay. Do these lines need to be connected anywhere specific? Thanks.