Hi Guys and Gals? (You never know )

With all the snow and frigid temps. all I can do is wait and think about what needs to be done to my 69 Cutlass covered outside. Have diagnosed and prepared for all issues but this one: The fuel needle is pinned to beyond full always. Thinking its the ground or is it the sending unit itself? Thanks and can't wait for Spring.

 

Your problem is an open circuit somewhere. Check the ground wire which connects the sending unit to the body. It could be in the sending unit itself. Or it could be in a wire or connector somewhere between the send unit and the dash gauge.

 

Thanks Doc,

That was my thinking as well. Will check as soon as winter is over

 

I had the same issue. There is a brown single wire in the trunk that goes to the fuel sender. If you locate that wire connector ground the wiire that goes to the front of the car. If the gauge goes to E you know the problem is between there and the tank. Either the sender or ground at the tank is probably the culprit. If the gauge does not move the problem is probably in the gauge or the hot wire feeding the gauge.

 

Thanks Sampson,
Your method of diagnoses is worth noting. Will do and let you know.

 

Thanks to all for your expertise especially Sampson. Grounded out the connector wire leading to the tank and the needle went to near empty. Broke the ground and it went back to beyond full. Will climb under when snow is gone and warmer weather prevails to check the ground at the tank and/or replace the sending unit.

You can always count on Fellow Oldsmen to solve a problem.

www.oldsmobilesforever.com

 

I had the same issue on my '70 Supreme back in the '80s. When I dropped the tank I found the brown wire had a push-on connector that went onto a stud on the sending unit. The connector was loose, so I crimped it slightly with pliers so it was a tighter fit and that solved the problem.

Now on the '71 I have the same issue, but it's intermittent. I discovered that if I grab the brown wire behind the license plate and pull on it/wiggle it, the gauge will start working again. I suspect it is the same loose push-on connector but these days I'm too lazy to drop the tank, so I just wiggle the wire whenever the gauge stops working.

 

I have had the same problem with grounds, and I have resolved many a poor ground problem by using what is called an internal / external lock washer. This type of lock washer has small barbs on both the outside circumference, and the inner hole. They are sometimes referred to as "star" washers.

 

Glad you are getting it narrowed down. I am not sure a sender for a 69 is the same as a 72. Maybe someone else can speak to that. If your problem turns out to be the sender and a 72 sender will work I have a brand new one in the box I will give you a good deal on.

 

You would think that the trunk drain plugs would be positioned where you could get to the sending unit wire without having to drop the tank. Oh well, it will be all in a days work sometime this spring. Thanks again