Fuel lines foe an electric fuel pump

[darepairman]

Hi guys, I am installing a Holly blue fuel pump with a return line regulator in a 72 dart with a stock tank, the question I have is can I use the vent line as a return line or will that cause neg. psi in the tank? I would rather not add a fitting to the tank as it has gas in it now.
Thanks in advance Ed

 

[clinteg]

You're gonna want to have a return line into your tank plus a separate vent line. Your return line should be as large in diameter as your feed line too. If you don't run your return line and vent line separate, yes you will create a vaccum in your tank and you'll more than likely start to starve your pump because the fuel won't want to gravity feed due to the pressure difference. It might be a pain now to drain the tank to add a fitting, but not near as much of a pain as it will be later when you starve your fuel pump and engine of fuel and can't seem to get it to run right or cause a lean condition at WOT and burn up your motor. Just my 2 cents.

 

[darepairman]

Thanks for the reply, its just the $.02 I was looking for. Looks like I drop the tank.
Thanks Ed

 

[Lelo Dart]

Think the new 3/8" sending units come with a return line fitting.

 

[67Dart273]

Agree with clinteg. In my opinion, the best way around this is to add a vent fitting up high on the filler tube just like the 69/ earlier cars did, and add a 3/8 return to the tank. This would allow you to get rid of all the 1/4" vent stuff if you want, the carbon can, etc.

 

[roccodart440]

Your return line should be as large in diameter as your feed line too.

Well.... not according to Aeromotive.

My system runs 5/8 to the engine with 1/2 return. That is to their recomended specs.

 

[darepairman]

I do have a new 3/8 sending unit that I installed a couple of years ago, Ill have to look at it