Ever since I have been working on my 7 I have been dealing with what I believe is vapor lock. The fuel pump runs but it will not push fuel until I disconnect the lines and run the pump. Once gas is moving, I can reconnect the lines and everything works fine. I did add a one way valve near the pump but that didn't do a thing. I think air is getting into the lines, the air has no place to go so the gas cannot be pumped in. What's the fix?

 

You need a fuel return line fron the carb or regulator

 

Guess I should have stated this. I am running a Dell 48, a holley red fuel pump and holley regulator. I will look into running a line from the regulator tonight. Thanks.

 

After checking I cannot run a return off my regulator. I have a holley 12-803, it looks like it has two outs and one in but no return. Any ideas? What exactly is the problem? The carb isn't getting gas but why?

 

You can mod the holley regulator or add a TEE in the supply line to your carb for a return. but you need to install a restrictor on the stock hard return fuel line. A fuel jet from a nikki carb or similar will work as long as it is wedged on the return line so it does fall or slide inside the fuel line.

However, i prefer a return from the carb...it prevents flooding also in case of a mishap.

 

Another option is a Mallory 4309 pressure reg. It has a real return fitting at the bottom. They call it the "bypass" I guess because it goes back to the tank.

With an fpr like this, you can run virtually any fuel pump and it will never vapor lock. I've got one in my car and have it set down to 2.5 psi for a hogged Nikki. The fuel pump is an MSD rated for EFI like 40gph at 43psi or something like that. Just stay away from the walbro because it's too big for this application. Your Holley pump will be fine, along with your stock 1/4" return line. Otherwise swap to a 3/8" return like they recommend.

If none of this makes sense, just go with Siraniko's recommendation.

 

I think I will try and modify the regulator I have.

Thanks for the help

 

I run a dead headed Dell with a carter pump and the holley fpr with no issues. You need to check
your vent line from the tank. If its clogged it will create a vacuum you can hear when you open
the cap and may be part of your problem.