Mach_1_II

I have a 2005 GT that is having some baffling fuel gauge problems. About a week ago I noticed that the fuel gauge was pinned empty. I filled up the tank just to be sure, and it stayed pinned to empty. Then the next morning, the gauge read a correct full tank. A day or two later, I noticed that the fuel gauge was pinned full and when I turned the car off, the needle would rest on half tank. It did this for a day, and then today I noticed it was reading correctly again. On the days it was reading oddly, it was sunny and in the mid 70s, and I am beginning to wonder if the heat is affecting it.

This isn't the first fuel system problem this car has had. When I bought the car 2 years ago it had 23k miles on it and signs that it sat around a lot. The first time I went to see the car, it was running rough, and then after a little bit, it wouldn't start at all. The Buick/GMC dealer I bought it from replaced the fuel pump. It ran, but it still had fuel gauge issues. So then I took it to a Ford dealer and they replaced the pump a second time, and that fixed the problem. But now with the gauge acting up again, I wonder if I should take it to Ford and have them take a look at it and possibly have it replaced again.

If you have encountered this problem or have any advice, it is much appreciated.

2005Redfire6

Sounds like the stepper motor in the gauge itself. It is a common issue in 2005 Mustangs and early 2006 I believe. I had to replace my whole gauge cluster but it can be repaired by the buying the stepper motors themselves and replacing them. My MPH, RPM, and fuel gauge went out before I replaced it. Sometimes they would act erratic or not at all.

ski

My 05 GT also has the same fuel gauge problem, which happens only when the ambient temp gets cold(45F and below). But I work around it by resetting the trip odometer at every fill up and gassing up at about the 275 mile mark(car gets approx. 20 mpg for the type of driving I do). Also, the low fuel light still works, which is the failsafe signal in case I forget to check the miles.

2005Redfire6

+1, my RPM and MPH were completely dead and wouldn't move regardless of temperature. However, the fuel gauge mainly acted up when it was cold out.

Nuke

+1 on the chronic stepper motor issue which plagues the 05's and early 06's.

Art161

Yes, it could very well be the stepper motor. Personally, I'd take a shot at something easier before going the replacement route. Try a bottle of Techron additive. It could be that the sensor is fouled and the Techron will clean it up. It's cheap, easy, and won't hurt anything if a fouled sensor is not the problem.

2005Redfire6

Meh, I'd still bank on the stepper motor. Pretty much every 2005 on here that complains of gauge problems in general is the stepper motor almost every time.