90 C4 Always Shows Full Tank

[rstauff]

I drive about 30 - 50 miles a week with the C4 and noticed for the past month that the gas tank never went down. Then I came out of a clients office and on the way home, noticed that I was riding on LO fuel.
From full to low in 10 miles.. I am guessing I am going to need a gas tank sender guage. Anything else I should look at before replacing the sender guage. NOTE: I see Ecxxers has a unit including the pump for $390. Figure that is what I need - but wondering if it could be something else?
Thanks - Rick

 

[toptechx6]

Try this

http://www.corvetteforum.com/techtips/viewsubtopic.php?SubTopicID=277&TopicID=2

 

[rstauff]

Thanks

I read the article - thanks for pointing that out. Sounds like the 62,000 I have on the car, and the second owner's parking it for a year or more, could be just the problem. Rust, dirt or whatever could be sticking there. But then again, what if I do not clean it all - or even see it all.

This will go into my decision to repair or replace. Guess I was correct in the sending unit is most likely the cause.

Again thanks for your help!

 

[RoyalViking]

I had the same problem after my 89 sat for a couple years and had condensation inside the tank (the tank was nearly full when first parked). Last year I drove the car about 450 miles and it sat again from June 2007 to this May of 2008.

I am not sure if I have another problem lurking there was no pressure at the manifold when I bled the system. In fact there was no residual gas at the manifold. There was some fuel in the hoses at the tank but it was minimal. i plugged the two larger hoses to keep more from draining out. The fuel pump holds quite a bit and you may want to try to drain it into a gas can.

I didn't have a chance to go to the chevy dealer to get the gasket and bought enough cork and paper material to make a new one depending on what I came across when I took the sender out. What I did find is that the gasket is rubber and can be reused. The difference in the gasket is that it can only go one way. You can flip it over and it would still work. The difference is there are 2 holes in the upper part of the flange and 3 holes in the lower. I reused the gasket after I cleaned the dirt and rust that had clinged to it. I'll post an update if I find that it leaks at all. On mine the wiper arm was shiny. What I did find is that some of the resistor wire looked like it was making contact. If any contact was made I never noticed it on the fuel gauge. I should have measured the resistance before I took the sender apart. I used contact cleaner (it was handy to rinse the area, WD40 would have worked too) and then with 600 grit sand paper I carefully sanded the resistor wire in the direction of the wire winding. The resistance once reassembled was 13.5 ohms empty and 112.5 full. I checked the sender after it was connected and I now have a working fuel gauge!

I hope some of this helps the next guy.

 

[WLS Ruby 93]

Fuel sending unit repair

Is it best to do this job with a full tank of gas or a nearly empty one.
Also, I would assume doing this procedure on a cold day would be best for reducing the fuming danger.

Keep on cruisin'
Bill

 

[RoyalViking]

Is it best to do this job with a full tank of gas or a nearly empty one.
Also, I would assume doing this procedure on a cold day would be best for reducing the fuming danger.

Keep on cruisin'
Bill

Good point!

I did this in the early evening when it was cool and the direct sunlight was not on the car. I had used a sealed flash light and made sure I turned it on and off away from the car as any spark could ignite the vapor. This is not a job I would do in my garage either!