My fuel gauge goes way past full and probably pegs when you fill the tank. Is this a gauge needle adjustment or the sending unit in the tank? I can't see that the sending unit would push the gauge that far above the full mark, but then again....I could be wrong. I was wonering if there is an adjustament for the needle position on the rear of the gauge or if I need to pull the tank and do something with the sending unit (or float, whatever they used). If the sending unit, how do you adjust that?
I'm also having a temp gauge that doesn't go very much into the marked running temp range. I replaced the sending unit at the thermostat housing area and that at least made the gauge work. I just think it should be showing a bit more than barely entering the run temp range.
Suggestions or help with these appreciated. Thanks

 

Pull the wire off of the temp gauge sender & ground it to the block right beside the sender. Turn the key to run and the gauge should read full hot.

If it does you probably have a bad thermostat.

Check the wire for the fuel gauge, if it's shorted to ground the gauge will go past full.

 

Yeah, that tells me if the temp gague is working, which it does. The engine gets hot but the gauge doesn't seem to be going up to where I would think it should. I'll have to check the actual water temp with my meter and thermocouple.

As for the fuel gauge. It also works but is just no positioning correctly with the gauge needle. I haven't trusted the gauge much below 1/2 tank because I might be almost empty. I've been resetting the trip meter and kinda going by mileage but that sucks as mileage can change drastically depending on how you drive.

 

I am curious if you have thought about changing the instrument cluster or least pulling it and cleanign all the contacts. Might try one of these maybe it will help. Dirty conections are not uncommon in our trucks becuase of their age.

 

Yeah the gauges on these things are a hoot.

The gauge for the front tank on my 87 shows full as it should, but stops dropping at the half tank mark. Go figure.

Rear tank works fine, so i've got a bad sender in the front tank.

Since your temp gauge does show full hot when you ground the sender wire & since you've allready replaced the sending unit, it looks like a bad T-Stat.

But, it sure cant hurt to check the temp with your thermocouple.

BTW, heres what the EVTM for my 87 shows.

All gauges erratic high or low: Check engine to body ground

 

> All gauges erratic high or low: Check engine to body ground

I agree this is a good place to start. It is a mesh cable near the pass. exhaust and frequently breaks. I run a ground directly from the battery to the voltage reg.(14 gauge), radiator support(12 gauge), body (12 gauge), exhaust (14 gauge), frame (6 gauge), and motor (6 gauge) on my older EFI vehicles. It solves a lot of problems.

I use a quality marine terminal with 5/16 studs on the + and - battery posts.

 

Your sending unit in your tank has more than likely craped out you will need to drop the tank and replace it.Your temp guage is probally fine if it runs in the first quater to half range, factory guages are not the most accurate.

 

Okay, from the experience of previously owning an '86 Ranger and now an '87 BII, the fuel guage situation is a 'normal' issue... even if it pegs high on fill-up. Of course, I have yet to own ANY Ford that didn't peg high on filling up. Anyhow, yes, the main issue aside from this is the innacuracy from half-tank to empty. The most likely contributing factors are a bad sending unit/float and/or wiring.

As far as the temp gauge, there are several issues: 1) bad temp sender 2) bad gauge 3) bad engine-to-chassis ground 4) bad thermostat 5) the most OVERLOOKED problem... cooling system dirty/clogged. If you haven't replaced the sending unit/thermostat, when you pull them, if they are all gunked up, I would highly suggest a VERY thorough flush. That's just my $0.02