I have a 1985 F-150 4x4 with a 302. The fuel gauge and the switch that changes tanks does not work. I Realy don't know where to start, and am tired of running out of gas. Please help..

 

These threads from the 73-79 forum apply to your truck as well.

https://www.ford-trucks.com/forums/1...uel-gauge.html

https://www.ford-trucks.com/forums/1...-1-2-mark.html

https://www.ford-trucks.com/forums/1...f-the-peg.html

for electrical values & illustration..see center of this page.

http://www.clubfte.com/users/mil1ion...strations.html

 

Hi TxMac4x4, first off I am a new user too.. I also have the (almost) same problem.. it seems that this is a common fault with these years (that's what I hear)...
when did they fix the problem, I don't know...
So to answer you, welcome to the club.

A couple of question... Do you have I tank or two? OK, I see your post, you have two.. Is the problem with one or both tanks?
Is the non working guage, not working all the time? Meaning is it intermittent? Have you seen it work before?

What I have is one tank not working at all. No guage, no gas (pump problem).
I also had a problem with the tanks fill hoses... and so, I am trying to fix both of these problem at the same time.. so I lifted the bed off the truck..

I have found out something is not right with the wire somewhere in between the rear tank and the toggle switch on the dash. OR (that's a big "or") the dash switch might be at fault.. my search is just starting to figure out my problem.

Are you gonna do your own work? Someone gonna help ya? Do you have the tools?

If you post the questions here I am sure someone will help with an answer, they did for me..
If your running out of gas, aren't you watching how many miles your driving?

 

thank ya'll for the help. this weekend I am going to take the bed off and see whats under there. I will let yall know how it goes.

 

To give you an update on my progress.....
The bed has been off for a week or two. I have had time to "play" with the conections. To see what is (not) going on. I had bad time with the back tank. I couldn't get fuel out of that tank. But the guage was working on that one...

So I took a volt meter (didgital) and a couple of very small screw drivers, the screwdrivers were for making contact with the little female conectors of the plastic conector of the fuel tank. phew! was that long to explain....
Turned on the volt meter to see if any volts happened at the plug.

Without the engine running when you turn on the key, make sure your on the right tank (front or rear), and at first I recorded no volts for the pump circuit, but volts for the guage circuit. this was for the bad working rear tank...
I went and checked the good working front tank. everyting checked out..

To the rear tank again. This time I fiddled with the toggle switch on the dash (it's located to the right side of the heater control panel). I just worked the toggle back and forth a bunch of times thinking that maybe it just needs to be worked to make a good contact... hunch was right.. checking the female conectors at the plastic plug on the rear tank and it was working (or at least I did have volts for the pump circuit).

Both circuits for both tanks seem to be working. After taking a small wire brush and cleaning the "pins" on the tank(s). I added some dielectric greese to the male and female ends of the plastic plugs. Put the plugs in place, added a bit of cyclone in little spots here and there to help hold the plugs in place. and call it good.

I did put a little gas into each tank and it seems that it was not enough.. but I did get the guage to move when each tank was selected... (didn't happen before on the front tank)
I will run the engine to see if I can get a fuel flow from the rear tank as I was not able to do so before....
I love this stuff....