Stock 69 Camaro has 2 lines going from the tank to the fuel pump. Why?

[parsonsj]

I've got a customer's car that I'm upgrading. 69 Camaro SS, 350, Q-Jet, 4 speed, numbers matching sort of car.

It'll be getting a PT upgrade (LS3/T56, etc.) soon, but I've got a question about the car in the interim. It has two lines coming from the tank to the fuel pump, 3/8 and 1/4". I'm certain the 3/8" line is the fuel supply line... but what is the other line?

Anybody got a clue?

thanks!

[BFG Man]

It's the return line... it also prevents vapor lock in hot weather.

[67 caprice]

My 68 442 has the same 3/8 and 1/4 lines from the tank to fuel pump. the 1/4 is the return line.

[parsonsj]

I hear you guys about a return line, but nearly all cars built then only had a supply line. Return lines are for EFI systems... near as I can tell. A return line implies a regulator... are you saying the fuel pump in a 69 Camaro has a regulator built in to it?

Just trying to understand the idea a little better.

thanks!

[MrQuick]

I read a very long time ago that the vent is there to help the fuel system prime quickly and to help with vapor lock by keeping a continuous flow of fuel. On some years the line connects to the fuel filter. I have noticed that it was more prevalent on high performance versions.

Thinking about it, it might actually pressurize the tank a bit, maybe just a bit over atmosphere.

Not regulated it comes out the same pressure as the outlet line.

[parsonsj]

Thanks Vince. That might explain why it's on some cars but not others.

[bretcopsey]

This grid on CRG site covers application of two vs. single fuel line:

http://camaros.org/diffs69.shtml

[kawaden]

Did the car have factory air conditioning? It was used to help stop vapor lock due to the extra heat generated by the A/C.

[parsonsj]

Thanks all. All that stuff is now long gone.

No, the car did not have factory air -- it seems it was a New York car, and how it survived in that winter salt environment is a miracle. Anyway, I've just started a project thread on the car, though it's already pretty well along.

https://www.pro-touring.com/showthread.php?89649-II-Much-Fabrication-is-building-a-69-Camaro