Fuel gauge issues

[SilverRiff]

So I have had my 1987 Monte for a month or so, and drove it around here and there while I'm sprucing it up. I THOUGHT I was getting really good gas milage because according to the fuel gauge I have barely used a quarter of a tank of gas, but after calculating that I am in all likelihood not getting 65 mpg, I stopped to fill up today and it took me alittle over 17 gallons to top off. I think the tank holds around 20 or so? So yeah the gauge wasen't working. But then the weird thing was that when I got back in the car and started it up, the gauge went to full as it should. What's the deal? I can understand if it was bad, disconnected, and didn't work at all, but why would it go to full like that? Any ideas??

 

[pontiacgp]

if you look at the tank strap on the rear of the tank on divers side you'll see the ground wire held in by a small bolt. Make sure that is properly secured and it has a good contact. In that area you'll also see a connector with a pinkish wire going to the tank. Make sure the connection is clean

 

[RITTER]

It could possibly be your sending unit sticking

 

[carmangary]

Sounds about like mine. I fill it up once it goes to the half tank mark. It stays stuck on Full for days then drops. Thanks for the tip about the wiring. I will try that on mine this weekend.

 

[84cutspreme]

Yea i agree, either a ground problem or just float getting hung up. I also believe that all the g-body tanks hold 18 gallons. I know the cutlass fuel tanks are.

 

[SilverRiff]

Wow 18 gallons.... So I only had about half a gallon in there. Good thing I stopped and filled up! What kind of gas milage should I expect out of this tired little 6 cylinder?

 

[Peter]

Wow 18 gallons.... So I only had about half a gallon in there. Good thing I stopped and filled up! What kind of gas milage should I expect out of this tired little 6 cylinder?

depends on your rear end and how well it is tuned/running but if i was going pretty easy on it i could get about 16 or 17 with a 2.41 mostly non highway driving