fuel gauge goes way over full... any ideas?

[NFGTragedy]

My car is a 4cyl to 5.0 swap car and after swapping to 5.0 gauges and putting the key in the on position where the gauges kick on I noticed that my fuel gauge goes wayyyyy over the full position... it actually goes behind the plastic trim of the gauge cluster... any ideas on what is causing this??... Is there a sensor on the gas tank that could be wrong or what?... I tried both the 4cyl and 5.0 gauges and both read the same over full... Any ideas where to start my search?

 

[Roland69]

mine goes way over the full line....but not so far that I can't almost see it.

 

[Euphoric306]

yea mine goes a good 2 or 3 mm over the full line, and you should be thankful your fuel gauge responds to the key on. mine takes a while after the car has started to setlle into one spot

 

[feifong]

same thing with my 4 banger it will go behind the trim and read FULL all the time. What causes this?

 

[bretamo]

Not that this is the solution, but when I removed the gauge needles to put gauge faces on my 92GT, I went to the gas station and filled up before putting the needle back on....I mean as full as I could get it it...and then I put the needle back on with it directly on the full line.

I recently ran the car out of gas for a fuel pump upgrade, and the needle only dipped a millimeter below the EMPTY line.

So this whole process calibrated that gauge pretty good.

 

[88Stang331]

I have the same problem, and no clue as to what it is. Maybe its the float/sensor in the tank thats throwing it off, or maybe its the cluster. I for one have no clue, but i'm looking to buy a new gauge cluster anyway because my speedo is waaay off.

 

[Bladez5_0]

Has your stang been regeared? Might want to open the diff and see what gears are in it and what gear you have driving the speedo cable before you go after a new cluster. Does the needle go down as you empty the tank? If not you might want to drop the tank and check the float.

 

[89Notch]

stock gauges are useless

 

[NFGTragedy]

Has your stang been regeared? Might want to open the diff and see what gears are in it and what gear you have driving the speedo cable before you go after a new cluster. Does the needle go down as you empty the tank? If not you might want to drop the tank and check the float.

Just curious how I would check the float? What would I look for?

 

[Bladez5_0]

Pull the assembly out of the tank. Have someone watch the fuel gauge while you move the float up and down by hand. You may want to have a bucket or a bowl of gas to keep the suction of the pump in while you have it out of the tank and power applied.

 

[Daggar]

Pull the assembly out of the tank. Have someone watch the fuel gauge while you move the float up and down by hand. You may want to have a bucket or a bowl of gas to keep the suction of the pump in while you have it out of the tank and power applied.

Better yet, disconnect the fuel pump relay under the driver's seat.

 

[CobraGT87]

the reason for the fuel gauge issues lies with the sending unit & float arm.. mine did the same thing. it would read way past full, then all of a sudden start dropping fast.

I changed the sending unit in the tank and now the gauge doesn't go up as high past the full mark and comes down much more slowly & evenly according to how much gas is in the tank. it's almost dead on now from full-empty.

The sending unit's float arm is barely making contact which in turn determines where your gauge reads. the next time you pull your sending unit, check the float arm for resistence. the more resistence you feel, the better, if theres hardly any, time for a new one as thats what cause fuel gauges to read so screwy.

been there, done that, wondered the same thing, fixed.
it

Scott