Fuel Guage shows way over full

[Maniak]

Nope, I'm not sure.. I'm just going by what I read here a while ago.

I do know I can fit close to 22 gallons in our '92 4 door tank (its a little less now that I dented the tank).

~Mark

 

[Rhett]

You got me curious, I will have to measure the dimensions of the gas tank on my friends 93 XLT and compare it to my 94 Sport gas tank dimensions...

 

[StaTTiKK]

How you doing man? I have a 98 Mountaineer with this same problem. The gas guage is pinned all the way full, while the computer in the console reads that I have a low fuel level. I don't know it is confusing. I have unplugged the electrical connector which goes to the gas tank and is located near the drivers rear wheel well. When I do this, the guage stays all the way full. Does this suggest that my problem is not with the float but instead with something forward from the tank?

 

[Tony H]

If the gauge gets out of spec as you say it is, you better bring a few gallons of gas with you, You may be bone dry at 1/4 tank.

That wouldn't be funny.

 

[Critter92X]

My 92 and 93 both have a 19.3 capacity.The book says the 91 is the same(I don't know myself)Mine also holds about 22 gallon if you top it off.When I first bought my 92 someone had put in the whiteface guages and got the gas gauge off,it ran out at 1/4 tank.So I put in 11 gallons and moved the needle to 1/2 it seems to be pretty accurate now.

 

[Creager]

The highest ive reached is 21.333 gallons... i cant remember if that was a time i ran out of gas or not. Maybe the gas station is lying! I've gotten it over 19.3 gallons, im thinking it adds two extra gallons with the filler neck.

 

[Critter92X]

The highest ive reached is 21.333 gallons... i cant remember if that was a time i ran out of gas or not. Maybe the gas station is lying! I've gotten it over 19.3 gallons, im thinking it adds two extra gallons with the filler neck.

That's probably about right,When mine ran out I put in 11,set my gauge then drove to the station and put in about 11 more.I probably used the 7/10ths or so going to the station.

 

[ghedrick]

Fuel gage reads 3/4 at start and moves to over full

Back to the problem...

I have cleaned the 4 pin connector with contact cleaner - no change.

I will check the connecting wires for loose or open connection.

Ammeter gage sometimes bounces but suspect alternator problem.

What wires are to be checked for resistance at the 4 pin connector "
I have read here that 160 ohms at full and near zero at empty are to be expected - but which wires ?

Previous owner claims to have replaced the fuel pump. I also read here that the sender may have been positioned improperly.

 

[Bwana Bob]

Fuel sender wires

On the 4 pin connector:

Pink/Black (Pink with black tracer) = Fuel pump +12 V

Black = Fuel pump ground return

Yellow/White = Fuel gauge sender

Orange = Fuel Gauge sender ground return

Also, you might check/clean the contacts on the big round bulkhead connector that brings the cables through the firewall into the driver's side footwell, under the dash.

Disconnect the battery negative before unmating connectors and making ohmmeter measurements.

Bob

 

[ghedrick]

Fuel gage shows way over full

My connector is on the driver side, I think when someone
replaced the fuel pump they rerouted the cables to that side.

In the connector:
My wires are Orange & Grey opposite each, and
Red and Black opposite each other.

I read infinity between the Orange and Grey; and
assume there is an open in the tank at the float
connection.

I further assume I must remove the tank. Hayes mentions a special
tool to disconnect the fuel lines. Anyone know if this is required on
a 91 ?

 

[sirhk100]

ANCIENT THREAD BUMP! But hey, can't claim I didn't search...

Gas gauge has worked normal for quite a while with no issues. I filled up this past weekend, all normal. Drive 20ish miles of highway, then 16 miles of pretty washboard dirt road. Hop back on the highway and the needle is pegged way past full. HUH, that's not right! No biggie though, I had reset my odo and figured I had a 200+ mile drive home, I'll base gas off mileage and figure it out later. I assumed the needle had stuck and just like mentioned here, figured, bad sending unit, wire issue, faulty gauge. So I'm driving and driving and I notice, crap, it's actually working, it's now down on full and I've gone about 120 miles. Sure enough, around 200 miles it's now reading about 3/4's of a tank. WTF??? So the gauge seems to still be functioning, it just seems like the range in which it functions has drastically shifted. Is that possible?

I read in this thread Maniak mentions pulling the cluster and physically pulling the needle and realigning it. Could the needle have simply somehow slipped on mine? Maniak, do you by chance remember how difficult this was to do? I can get the cluster out but then was it just a matter of pulling the lens and simply by hand pulling the needle off it and realigning it?

Any ideas? Right now I'm leaning towards doing just that, fill the tank full, pull the lens, turn the ignition on so that it should read full and then put the needle to where I want it. Any other ideas beyond that though?

 

[Maniak]

I would check the impedance of the sending unit first to see where the problem is.

If you have access to an electronics store (maybe RadioShack can help) you can buy a potentiometer to test the gauge.

The sending unit should read about 145 ohms empty and 22 ohm full (That's from an old thread by DannyBoy when he was rebuilding his dash).

So, With a potentiometer AND DVM you can set the pot. to 145 or so ohms and make sure you gauge reads empty and then do the test again at 22 ohms. If the gauge reads correct then you have an issue with the sending unit (bad).

I would test this by disconnecting the wire from the sending unit at the tank. That way when your doing the test your testing the gauge and the wire at the same time...

Now, lets assume that when you use the pot that the gauge doesn't read correctly... That means the issue is in the wire or in the cluster.. At that point I'd pull the gauge out and use your DVM and measure across the sending unit wire that goes to the cluster. If you seeing the same impedance there that you set the pot. to then you know the issue is the gauge. At that point you can pull up on the needle to remove it and reset it or just replace it.

If you can't find a potentiometer then you can at least use your DVM and measure the impedence on the sending unit wire and see if it matches about how much gas is in the tank. If you have 1/2 a tank figure you should have around 100 ohms on the wire.. The sending unit ohm value should be linear... sso you can figure out what impedance you should be seeing.

hopefully that all makes sense.. it did when it was in my brain..

~Mark