C2 Fuel Sending Unit False Reading

[Mark P.]

I pulled my 66 fuel tank to repair a slight leak and after repairing it and re-assembling, found that the gauge reads 3/4 full with only 5 gallons in the tank. After moving the arm, (lifting the arm up and down in the tank) it won't read below 3/4, but will read full when the arm is lifted to the top. What gives? I was very careful with the unit upon removal and disassembly. Contacts are clean and bright.

What did I do wrong or is it just a sign of old age? (the sending unit, not me...or it could be me, too.)

Any advice would be appreciated!

Mark

[Jack H.]

Re: C2 Fuel Sending Unit False Reading

Mid-year cars used a special circuit topology for the gas gauge (based on Whetstone bridge construction) making them independent of absolute B+ voltage. Typically, performance hiccups deal with wiring fault(s) especially getting good ground at the tank sender.

The 1963 Corvette Shop Manual had a nice theory of operation + trouble shooting chart based on symptom. I'd attach a copy, but it's a 425Kb .DOC file and the site's attachment manager says the limit is 97.7 Kb for uploading .DOC files...

[Mark P.]

Re: C2 Fuel Sending Unit False Reading

I've got the manual...I'll check it and see what it says. Thanks for the input.

Mark