Fuel Gauge Reading 3/4 or more...

[Mark P.]

My fuel gauge reads full when full, but unly reads correctly until three quarters full, then it stops there. Is that a gauge problem, a sending unit problem or a wiring problem? I have moved the sending unit in the tank up and down and that's all it get....3/4.

Any ideas?

Thanks,
Mark

[John H.]

Re: Fuel Gauge Reading 3/4 or more...

Mark -

Sounds like the sending unit - the diagnostics article at this link may be helpful.

http://www.lbfun.com/warehouse/tech_...rFuelGauge.pdf

[Mark P.]

Re: Fuel Gauge Reading 3/4 or more...

Thanks, John. I thought it was the sending unit, but needed some definitive instructions other than the repair manual. It was not very helpful. Since it worked before I repaired the tank, I thought I might have damaged it in some way, even though I was careful. I'll test it, make sure what the problem is and get it replaced/fixed.

Thanks again,
Mark

[Mark P.]

Re: Fuel Gauge Reading 3/4 or more...

If it is the fuel sending unit for sure, would I need to find an NOS unit, or is there an acceptable reproduction unit out there that gives good readings? I heard Corvette Central sells a decent reproduction unit (from this article and from other sources), but not sure. I have hear discussions on this in the past, but I'm not sure anything definitive came out of them. Any advice would be great.

Mark

[Jack H.]

Re: Fuel Gauge Reading 3/4 or more...

When the Whetstone bridge circuit topology made its debut (makes the gauge reading INDEPENDENT of specific battery voltage), the service manuals described the new circuitry and gave technician troubleshooting directives based on symptom. For Corvette, these can be found in the Corvette Shop Manual.

From the 1963 Corvette Shop Manual, a symptom that sounds like it might apply to your case is:

"Pointer needle does not read below 1/2 position"

With the troubleshooting advice:

"Poor connection of terminals in light green wire or break in light green wire. Check connections at connector. Check continuity of light green wire between connectors."