# Fuel Lines



## redlineevents (Aug 18, 2014)

Can someone tell me the difference of having two fuel lines hooked up to fuel pump vs one line? My first 66 Gto (clone) had two fuel lines hooked up to fuel pump and this new 66 has just one. Isnt there supposed to be a return line somewhere? Any help or guidance will be appreciated. New to website.


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## 646904GTO (Feb 10, 2008)

I think California cars had a pressure bypass line on the fuel pump back to the tank. Emissions related I believe.


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## Roger that (Feb 6, 2010)

Are you asking about the fuel filter having an extra line? A/C cars did have an extra return line from the fuel filter back to the tank.


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## pjw1967 (Mar 10, 2014)

Roger that said:


> Are you asking about the fuel filter having an extra line? A/C cars did have an extra return line from the fuel filter back to the tank.


My '67 a/c car has the tank return line. Idea was to prevent vapor lock due higher engine room temps. However, it connects at the fuel pump.


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## Roger that (Feb 6, 2010)

I think 1967 was the 1st year of the fuel pump return so the original poster might have had a later year pump on his 66 at one time. So A/C is the answer to your question.


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## geeteeohguy (Feb 2, 2008)

'66 and early '67 cars had the 1/4" vapor return line at a canister fuel filter mounted on the intake manifold by the thermostat. Late '67 and up cars had the 3-line fuel pump. The return line was used with HD cooling systems and AC equipped cars. My early '67 has the return line at the filter,and an HD cooling system, but never had AC. On my '67, the fuel return line helps, especially with today's lousy fuels. '65 and earlier did not use a vapor return line.


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## Roger that (Feb 6, 2010)

Hey geeteeohguy, 65s with A/C did have the return line as well. Maybe even the HD cooling option? My 65 A/C has it.


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## redlineevents (Aug 18, 2014)

my current 66 is a non ac car and has one line coming from frame/tank to fuel pump.


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