Garon

Hi All-

I did some searching and didn't come across this topic. Maybe someone can shed some light on the subject.

When I fill my 2000 Chevy Silverado (120,000 miles) to FULL, the fuel guage still reads EMPTY for a few minutes. It then quickly jumps up to the accurate FULL mark while driving. This sometimes happens when I am sitting at a red light (it jumps down to EMPTY for a few seconds then back up to the accurate level).

The movement of the car does not seem to affect it, the speed of the car doesn't seem to affect it and the weather does not seem to affect it. It sometimes happens when the car is cold and sometimes when hot. The one time I can ALWAYS reproduce the problem is when I first fill up and then drive away. It takes about 30 seconds before it jumps up to the FULL mark.

Any ideas?

therewolf

Could be a loose wire either at the sender, gauge, or ground. (Pssst, what the hell, check 'em all!)

After that, the sender is the prime suspect, barring a broken wire.

ukrkoz

let me know when you find good solution, one without truck bed removal. mine does exactly same. I think, I ran tank real low on gas - and that tripped it. ever since, it does that crazy dance.

Garon

Rivereye - Thanks for the info. If there was a short, wouldn't this be an "all or nothing" thing and not randomly occur when sitting at a stop light?

ukrkoz - Sure thing. The next time it is at my mechanic, I will ask his advice. If it does involves something like removal of gas tank, he'll recommend not doing it unless it is driving me completely bonkers.

therewolf

So at idle while not under load. May I also recommend you consider you engine-to-firewall ground strap. I'm not doing you any favors here, the cables on these trucks are a stone b!tch to replace.

I'm having grounding issues, and I've started changing all the cables myself, I know.

FYI, the negative cable engine bolt may be visible thru the skirt under the driver side fender-well. It's probably 1/2". Use a 1/4 drive socket or a six-point socket if you can.

ukrkoz

and here's observation for both of you.
I had him refilled yesterday, so gauge is still in the jumping phase today. I was next to pulling out of parking garage, and decided to shut down music, so that I can communicate with the attendant.
Engine started fine, then, there was several discharge noises coming straight from the instrument cluster - and needle went boink down to empty and light came up. Discharge noises like in an electrical discharge, also known as spark. Needle came back to norm about 15 minutes down the road, as usual.

just an observation, before we start ripping truck beds off to get to the sending unit. Damn straight from the instrument cluster. left hand side to the steering wheel. Is that where the engine negative bolt is behind the firewall?

suzuki-guy

my 95 does that i do not worry about it though

suzuki-guy

I always thought it was ashort in my truck

98white5.0

There just must be something wrong with the instrument clusters on these trucks. Mine vibrates like a hummingbird and shows empty when I still have half a tank. It really acts like it thinks it has a 17 gallon tank instead of 34. After replacing the fuel pump, the gauge problem is still there. So I will just live with it. I figure the instrument cluster will have to be replaced. IDK besides that.

therewolf

The engine/firewall ground strap connects to the firewall just in front of the radio on the firewall in the engine compartment in my truck. Other years and models may vary somewhat.

Sometimes I get a clicking from under the dash, but since it sounds like the CPM when it's being reprogrammed, I just ignore it. It's partially my fault because the radio isn't turned up loud enough.

Maybe I'm just lucky, but so far the only problem I have with my gas gauge is it runs to empty far too often.