Gas Tank

[93zierra]

Hey guys I've got a 2000 gmc, but its a 3/4 ton ccsb so it's an obs. My fuel gauge doesn't work correctly it bounces so fast that the needle is a blur and doesn't read correctly. But what worries me is when I go to put gas in the tank and unscrew the cap it sucks alot of air. Also when I park it and shut it off within a minute or two I can hear the gas tank "pop" back out. Kinda like if you suck all the air out of a pop bottle and then let it go back. Any ideas or advice would be great! My truck also doesn't seem to have the power it should thought maybe this could be part of it. Thanks in advance!

Edit: I have already chnaged the gas cap, didn't help.

 

[93Chevy_1500]

Have you tried not tightening the gas cap as tight as it will go? Leave it a few turns from tight.

 

[DRAGGIN95]

The fuel gauge issue is very common on the 95+ dash, the little servo motor that is in the cluster is going bad, I myself have had 2 of them do that, you can either swap out the whole cluster, or replace that motor.

 

[93zierra]

Yeah I've tried not tightening the cap and changing the cap. I figure the gauge issue is either the sender or the gauge itself but I just threw that in there for extra info incase it had anything to do with my other problem.