Fuel Gauge Problem

[TJAXFF]

I just filled my 98 Eldo with premium 91 Octane ( Coastal Station ), right after that I started having problems. Fuel gauge is going from full to empty, with warning signal and low fuel coming on and off constantly. I checked everything in the manual, even took off and replaced cap several times and several clicks. Still no luck. Just purchased the car a month ago, has 42K on it and still learning about all the gadgets, I did notice that the manual says not to use fuel containing (MMT), if I did, would this be my problem? Or does something have to be re-set?? Any answers would be appreciated.
Thanks, TJ

 

[Jibit]

Was the car running when you filled it up?

 

[TJAXFF]

No, I already made that mistake, which brought the check engine light on, but had that cleared at the dealership. This is a new problem.

 

[Sifrino3]

Was the car running when you filled it up?

at:

 

[Pepsi2185]

If it is the float system it could be a bad ground or a short at the gauge.

But my vote goes for the sending unit. Thats a guess mind you, you should still grab the sending unit output to the gauge and test it. The resistive element may be screwed up, but since its the light and the gauge screwed up i dont think its the cluster.

 

[sentra2nr]

I am going to agree with ^ on that one. Sounds like the sending unit has gone kaputsy and now you are left in check engine light hell. is the car running funny, if not your fuel pump is still doing its job, you just need the sending unit.