Hey Guys - hoping someone on here might help and apologies for the long post.

I have a stock 90 5.0 TPI which had a fuel gauge showing 1/4 tank all the time. Took it to a shop who worked on the cars at a dealer in the 80's and they diagnosed a faulty fuel sender. They replaced the sender and pump and it still read 1/4 tank so they determined it was a faulty gauge cluster. They sent gauge cluster out for repair, it came back and was now showing 3/4 with a full tank. And the gauge moved up and down when gas sloshed around in tank.

They took the tank down again, topped it off and the car is now showing slightly over 3/4 with a totally full tank. They tested the connection and apparently the sender is only showing 87 ohms when it's supposed to be showing 90 for a full tank. The shop now thinks the gauge cluster wasn't calibrated correctly and are planning to send it out for repair again.

I should add that the new sender is a GM Direct AC Delco replacement(#19111386) and the shop did say the arm was a different angle than the OEM so not sure if that's an issue. They also said the connection on the Fuel Ground and the cluster wires were all cleaned.

I'm hoping someone on here might have any suggestion or hopefully a solution to fix this and thanks in advance.