I just purchased an 87 truck and the list of things that work are shorter than those that don't (haha). It has dual tanks and the fuel gauge reads full on both tanks, well the pointer goes well past the full point and almost points horizontally right on both tanks full or not and I was wondering if this would indicate a problem with the gauge or should I look elsewhere first?

The power locks and right power window do not work, is this more or likely a switch(s) problem or again should I start searching the wires?

All the fuses are good, if that matters.

Any help appreciated, thanks you for your time

 

I have a 87 F150 also and the fuel gauges do the same thing.
My gauges stay past full till there is about 4 or 5 gallons
left in the tank and then it moves over to empty.
I don't know what the problem is but i just keep gas in both
tanks and set the tripmeter back each time I fill up.
Don

 

Interesting I just purchased the truck and just filled it up and noticed that so I will see if it does the same as yours, if it does then I am sure it is the gauge itself. Thanks for the input

 

The problem you describe is pretty common if the sending unit in the tank has worn bare spots (no continuity) in the resistive element. The only cure, I'm afraid is to replace the in-tank unit. If there's a fuel pump combined with the fuel level sending unit in the tank, you're talking about $150. The cheapest way out is to reset the trip meter and keep track of miles like was suggested by the other post. Sorry about that.

 

My 87' 4X4 does the exact same thing. I've been doing the odometer trick so far but I hear that both tanks electrically go through your dual tank switch and if that switch, reguardless if it actually switches tanks, has wear or a short, the guage will be screwy. Haven't had much time to do it myself but If you do, I hope it works. C Ya

 

Well the fuel pump is mechanical on the block, I have not had a chance to trace the line and look for shorts, dirt or faulty pieces but when I do I will let you all know if I get the fuel gauge working or not.


However I messed with the power locks and windows last night and after checking the wires motors etc I thought I would lose my mind. I checked the actual switch itself and took it apart, the little brass I will call them points that direct the power were covered with crap there is a word for it but that is the one I will use. After cleaning them the power windows and locks work man I bet whoever owned this thing before would kick themselves if they knew, no telling how long they went without being able to lower the window and lock and unlock the doors. So if someone is haveing similar problems you may give that a try. I will almost bet that the fuel switch is dirty underneath as well I guess I will find out. Appreciate the responses

 

I made an earlier post on this, but it must have been misleading.
Anyway, regarding the sending unit, I did repair mine. It was not the resistive part that failed, but rather the grounding side of the slider, which must slide against the steel housing. This was totally corroded on mine. I wrote up the whole ordeal, of dropping the tank, replacing the fuel pump, and repairing the sending unit.
The write-up is at my web site: www.winfordr.com/FordTruckStuff/f150tank.htm
And I have posted some relative pictures, though not the whole project.

Keep in mind that the Fuel gauge will read Full if the wire from the sending unit is OPEN, and Empty if it happens to short to ground.

Good Luck!

Winford

 

'87 musta been a problem year for these. My front gauge works ok, but my back gauge stays totally full till I have half a tank used. Then it starts bouncing ... yes bouncing just like this guy till I have about 5 gallons left then it bottoms out and rests. That's when I know it's time to look for fuel cause I only have 40 to 60 miles left. I only ran out once when I underestimated my fuel economy when towing, but it would be nice to have a non fuel guage.
Tony

 

I'll look at your site, my guess is it is the same problem as what you had. Appreciate it