I recently changed from the stock tank to a RCI cell (20 gallon) and I have some new problems. The gauge reads past full when not connected to the sending unit on the cell, and goes to E when I ground it, which is correct right? The problem is I have nothing in between.... I put 5 gallons in the tank and it stays on "E", added another 5 gallons still was on "E". So I pulled out the sending unit checked to make sure it was a GM, turn it upside down 90 ohms (simulated full) right side up 0 ohms (simulated empty) put it back in and now the gauge goes past full when I plug it in on the cell, and stays there. If I ground the tan wire it goes to E.... What is the missing link here?

I am trying to drive it to Pleasanton Good Guys tomorrow so the more ideas the sooner the better...

Thanks guys!!!

tan wire isnt a ground
tan wire hooks to where you read the 90 ohms on the sending unit.
now another wire should hook to the body of the sending unit to a good ground.
the sender wont work properly without a good ground.
if you dont have anything in between then you got a bad sending unit.
you can check that by using a digital ohm meter on the sending unit while its on the bench.
black lead to sender body red lead to terminal where the tan wire goes.
move the float by hand and ohms should go from 0 (empty) to 90 ohms (full).

Thanks Dawg, I got dirty hands as I type this, I will try this, what I am getting on the ohm meter is 1, when the tan wire is connected to the cell and I have the sending unit grounded directly to the battery. I am pulling the sending unit now. If I still get a 1 what does that mean?

When I connect

OK just tried this on the bench new sender from the cell, empty - get almost 0. Barely move the sender off of empty ohm meter goes directly to 1, not to 90 or anything else. If I move the float I can get a reading for a second but the readings are all over 180...... Does this sound like sender to you?

Did same test on stock tank and it was accurate, read almost 0 on empty and a little over 93 @ full.... Did I do the test right?

changed a couple settings on the ohm meter and @ full float all the way up I get 559 ohms!!!! Bad sender right?