Fuel Sender Question

[cblazer1500]

I'm getting some rear frame rail work done and to do so the fuel tank will be dropped. Now since the tank and sender unit is undoubtedly the original parts I'm gonna replace these. My question is there are 2 sender units available for my 1980 Cutlass, a 2 line and a 3 line... Now 1 line is for the fuel and the second is probably for the evap... What was the third line for? And how do I know which one to get without actually looking at the one I have in place now? Trying to get all the parts before it heads to the shop...

 

[crucial118]

3/8 would be supply, 5/16 would be vent/evap, and 1/4 return. I don't think the 80 had the return on the fuel pump or sending unit. My 80 Monte only had a 2 line system. You can upgrade your fuel system by installing a 3 line pump and sending unit if you want, you would have to run, or buy, a 1/4 line from tank to pump tho. That's what I am doing now.

Look up where the rubber lines turn to hard lines at the rear, near the passenger spring top. If you see only 2 lines coming off the tank, then you have the 2 line system. If there is 3, then you have the 3 line system.

 

[truracer20]

If you ever have plans to run an electric fuel pump the 3 line sender is what you need.