Gas guage

[Razr]

I just had my fuel tank sending installed and hooked up to the gas guage on the dash. There is one problem though when I let the truck sit over night and then in the morning use it the gas doesn't read. But then If I let the truck sit and use it in the afternoon it reads the gas what is the problem. When I turn it on the gas doesn't work then if I let it sit for 3 hrs or so it works.

[68gmsee]

You said you just had the sending unit installed but didn't mention if it was a new one or one that was a working one out of another truck. Could be it's defective. You may be able to isolate by grounding the sending unit cable and see if the guage works or if it's the sending unit.

If you do a search, there's been a lot of posts in past about this.

[68gmsee]

Here's the link that someone posted earlier that may help you...

http://www.6066gmcguy.org/Electrical-02.htm

Also, don't forget to check all the ground wires to make sure they're tight...