Filled up gas tank and gas gauge doesnt show it full

[savegoodautonfg]

I just filled up my gas tank in my 1990 Ford Mustang GT 5.0 and my gas guage doesnt show it to be full. It shows it on the line above the half mark. Anybody have any ideas? Cause it really sucks cuz now i'll be putting so much more gas in my car.

Any help would be appreciated.

 

[281pony]

sounds like an issue with the fuel level sending unit.

you sure its full?

 

[savegoodautonfg]

Positive.. I filled up to the point where it clicked.. you know what i mean.

 

[281pony]

yeah, sounds like its the fuel level sending unit issue.

although most of the time i hear them going out, it just pegs at full until the last 1/8th of the tank. then it just drops all the way back down.

 

[87'GTstang]

Again, fuel sending unit. All it is, is a rheostat with little wiper teeth that make contact on an electrically-charged metal strip. According to position of the teeth on the wiper, the varrying resistance is translated directly into position. The teeth get brittle and break off over time, so you replace it at this point.

 

[RYC CUKR]

While it is usually the rheostat sometimes that is not the only issue. The actual float that operates the rheostat on my 91 would come off. When that happened the car sat on empty perpetually.