Gas gauge not working

[SoulTerror]

When I first got my car it would read a full tank as 3/4 and go down from there. Now the gauge just stays at 3/4. I'm just wondering what could be the cause so I can get it fixed.

[meissen]

There's a floating level as part of the fuel pump assembly - maybe it's caught? Might be the sending unit going bad too?

[SoulTerror]

Well I guess it's a good reason I have a trap door then. Is the fuel pump sealed in anyway or just bolted down? I know he replaced the pump just before I got it, so maybe he messed something up when he did it.

[meissen]

If you have a trap door I'd definitely take a look and just see what's up - it can't hurt and it's rather easy to do depending on how good of a job he did on the trap door. When you uncover the door, check to see if he did it like this - http://t1.gstatic.com/images?q=tbn:w.../FUELPUMP2.jpg - if he didn't, cut the notch in the top left of the pic. Trust me - it makes it a lot easier to get the quick disconnect fuel lines undone.

Either way - pop a looksy and see what's up.

[Sideswipe]

It's either gonna be the sender, whoever did the pump bent the float when they were pulling the pump out... If I have to pull mine for any reason anytime soon (I hope not) I'll post pics of what it should look like.

[Fbomb]

I'm going to need to cut a trapdoor sometime soon...too bad my paint right there under the carpet is near perfect, clearcoated and everything!

[Sideswipe]

Nobody is going to look at it haha. Your carpet will cover it. For those of you who haven't cut the access panel: #1 Do it. #2 When you're doing it, cut very lightly. #3 I will post up pics of where you should cut later

[meissen]

http://media.photobucket.com/image/t.../FUELPUMP2.jpg

[Sideswipe]

Meissen, that is an awesome example of how to cut it! Better than how I did mine, mine is a little tight, but still very doable.

[meissen]

I did a regular square and then realized how much that "notch" really comes in handy. Next time I have to go into my trap door, I'm cutting the notch to make it easier to get to those fuel lines!

[Sideswipe]

Yeah, your pump setup is slightly different because it's an LT1, but same idea goes for an LS1 fbody.

[UjGearhead]

The sending unit is definitely a possibility, but GM also used crappy stepper motors in the gauge that can can cause that problem. The sending unit is essentially a variable potentiometer, so you can test the gauge and harness by jumping the connector at the fuel tank and see if the gauge goes through the full range. If it it doesn't, you can buy new stepper motors on Ebay for under $10. They're not THAT bad to replace if you have some soldering skills.

[SoulTerror]

That sound easy enough, any more information on jumping that?