Fuel Sender Issues

[Damien]

Hi all.

Looking for some advice.
I've had some issues after installing two new senders and their reading.
After installing both senders, the gauge reads with the ignition turned off and then goes to empty with the ignition on.

Everything was fine with the previous sender, it was still working but was corroded so I changed it when I cleaned out the tank.

TIA.

[earntaz]

Had the same issue with my 71 Nova ... check the instrument cluster/fuel gauge ground.

[Damien]

Well, pulled the gauge cluster out and bench tested the fuel gauge and sender and everything seems to be working so I'm at a bit of a loss.
The resistor on the rear of the fuel gauge is obviously ok as well given everything is working.
The sender has a good ground at the tank as well.
I'm wondering if the tan wire may be compromised somewhere between the harness in the front and the rear?
Remembering that the crusty sender and the gauge was working fine before the sender was swapped out. Frustrating.

[Damien]

Still no gas gauge unfortunately and not a fan of having things that don't work correctly in my cars, least of all the gas gauge.
I'm going to have another crack at this, this coming weekend I think and drop the tank again!
I'm thinking the the female connector on the tan wire from the gauge to the sender, may be a little loose on the sender pin.
Running out of options at this stage.

[SS427]

If the gauge reads empty with the key on and there is gas in the tank, then the tan wire is somehow grounded or pinched is my guess. Try unhooking the tan from the harness and with the key on, see where it reads. Then using a jumper wire ground the tan wire and repeat the test. The fact that both senders read the same can pretty much rule out the senders as being the issue. Make sure you reattached the sender ground to the body up above the rear differential. That could be a problem.

[Damien]

Thanks Rick.
I think you're right with the tan wire.
I'll check through all those items.

[Damien]

A bit of a report back for anyone interested.
The problem surrounds the sender being fitted in the tank and not wanting to work as I have connected 2 new and one old senders which all worked whilst connected into the cars system but outside the tank, but once installed in the tank, only the crusty old sender works. Needless to say that sender stayed in the tank. I thought the new senders may have been grounding out in the tank somehow when fitted, so I played around with the power strap off the sender to make sure it wasn't touching anything but it didn't seem to make any difference. Anyhoo, the crusty old sender stays in for now and I will look to find another OEM sender that I can have rebuilt to install at a later date.
Cheers.

[RPOLS3]

I am having this same issue in my Chevelle - installed new tank and sender last night to replace cursty but working original units. Tested new sender prior to install. Hooked up power wire to sender then hooked up ground, moved the float up and down and the gauge in the car worked as it should. Installed everything and put 5 gallons of gas in car and the gauge reads empty. If I disconnect the power lead to the sender the gauge reads full. I had to drill a new ground as the new sender wire was too short to make the old location work, thinking that might be the problem. Ran out of time and will try again this weekend......ugh.

[Bill Pritchard]

Originally Posted by RPOLS3

I had to drill a new ground as the new sender wire was too short to make the old location work...

I experienced the same thing 15 years ago when I got a repro sending unit for my old 69 SS396 convertible. They make all the rest of the sending unit correctly and then 'cheap out' by making the ground wire a few inches too short! When I called whomever I bought the repro sending unit from, they claimed they had no complaints from anyone else on that issue, which I found hard to believe. Solved the problem by returning the repro unit and sending my original to John Wolf in Ohio, who correctly restored my original sending unit.

[X66 714]

I bought 3 for the cuda. one single line & 2 double lines. None work correctly. They all are 1/4 tank off & no matter how you modify the float, doesn't help. It read 1/2 tank when it has 3/4. Better this way than the other.....Joe