C2 66 Fuel Gauge/Seding Unit

[Rich Freeman]

Thanks to all of your previous advice, I was able to troubleshoot my electrical problems on my 66 327/350. I found that my tank sending unit was bad and replaced it with a new AC Delco/GM unit. My problem is: after new unit installed and tank is completely empty, the gauge is not going completely to E. It stops around 1/4. Prior to installing new unit, I crossed pink & tan wires (because gauge was stuck on F - initial problem)and needle travels down to E. So, I assume gauge is good. I briefly compared new unit to old before installing and looked OK. Any suggestions?? Could float or something be bent? I looked into tank and float appears to be on bottom. I stuck my hand in tank (tight fit) and tried to nudge float down a little, but that didn't help.

[Rich G.]

Re: C2 66 Fuel Gauge/Seding Unit

I just did the same thing, but replaced the gauge also in my 66 and it works about the way you describe, although I haven't seen it empty yet as I did not do the work. The guy who works on my car owns a number of C2 corvettes and works on a lot more. His take on it is that the fuel gauge is merely a suggestion of the approximate fuel quanity, almost. As a newcomer I am interested in what others have to say and what you find.

Rich 38594

[Richard S.]

Re: C2 66 Fuel Gauge/Seding Unit

I think there are a number of posts in the archives which were detailed and should help you out. If I recall correctly,crossing the wires may have ruined the unit.

[Rich Freeman]

Re: C2 66 Fuel Gauge/Seding Unit

I'm sure the wires weren't crossed. I've looked through all of the archives and I'm getting conflicting info. With the tank sending unit on E (tank completely empty) I'm seeing around 15-17 ohms and when I move float up to full position, I'm seeing somewhere over 60 ohms(that's as high as my ohm meter goes). I'm going to try another meter. But in the archives some responses say when the tank is empty I should read @80 to 90 ohms & when full it should read @10-15ohms. (vice-versa). My sending unit is a new GM unit and the ohm meter goes steadly up through the movement of my float. The gas gauge appears to be good. When I jump the Tan & Pink wires the gauge moves to E. When I jumpthe Tan wire to ground the gauge reads full. I've checked all of the connections and they are good. So I'm about ready to throw in the towel and just figure my tank is empty when my gauge shows 1/4. Some suggestions on the archives say to bend the float rod. I dont think that is going to cure the resistance problem. Maybe I'm wrong. This is driving me nuts...

[Richard S.]

Re: C2 66 Fuel Gauge/Seding Unit

The sending unit in the tank may have been bad right out of the box. If I remember right someone who responded to one of my questions said that was very common with the new Mexican manufactured units from GM.