The gas gauge is stuck on full on my 1968 Buick GS 400 convertible. I think it is likely the fuel tank sending unit, but I am not sure if I should just get a new fuel tank too or just replace the fuel tank sending unit. Did these come with a 1 line or 2 line sending unit? Is there a specific brand of sending unit that is the best? What is the best brand for the fuel tank? Would this be the correct sending unit to get for a 68? https://www.stage1restoration.com/product/fuel-tank-sending-unit-1970/
https://www.v8buick.com/index.php?threads/fuel-gauge-and-sender-operation-and-diagnosis.330220/ https://www.rockauto.com/en/catalog...+v8,1379741,fuel+&+air,fuel+sending+unit,4436 I think the 1970 sending unit is the same, so yes, you can get it from Todd. If you have A/C, you need the 2 line unit.
Possibly, look at your fuel pump. If it has a vapor return line, you’ll have 2 lines at the tank. Look at the bottom of your fuel pump. If you see 2 hose connections, one 3/8", the other 1/4", your fuel sending unit will have 2 connections.
I just replaced mine and it was a two line but it had been replaced before by the previous owner so who knows what was original. I did have a used single line version in the parts box he gave me, not sure what it was from. You will need to look at what you have on there. My tank 2as clean and had been replaced before so I just changed the sending unit.
I think my fuel pump is original based on what it looks like (but not sure) and it has the 2 lines. Looks like the hoses have been replaced in the last 60 years. I just ordered new fuel tank sending unit from Todd.
