OK we are swapping the fuel injected 87 v6 with a carbed 383.

And I already took the tank out removed the electric fuel pump and plugged off the return line and vacume canister lines at the tank.

I installed a holley high flow mechanical fuel pump with a single line coming from the tank and a single line going to the carb.

My question is about what happens when the fuel pump fills the carb with fuel and it does not need any more fuel. The pump is still running off of the cam so it is still pumping right???

Is there a pressure relief vavle in the pump that turns the supply line into a return line. and if so does that mean that my fuel tank is being pressurized since I have plugged the vacume canister line.

I left the line with the small filter on it that hangs down by the driverside wheel in place with the filter on it. (is this line to allow air into the tank or is it a pressure relief line???

 

For decades cars only had a pickup line coming from the tank going to the mechanical fuel pump. My '57, for instance. The pump self-regulates, it simply isn't capable of producing more than 6 psi (or whatever it's putting out).

With this type of a setup, you need a vented gas cap in order to allow pressure into the tank, actually. AKA "air".

 

I see you asked on the Carb forum as well. The answers there were correct (and the same).

 

Ok so one line is good but what about the vent? is that line that hangs down in front of the left rear tire a vent. you know the one that looks like it has an in line small plastic fuel filter at the end of it??

If not do I go with a vented gas cap??? What about emission controls??

PS. I only posted this on the carburator board cause nodbody replied here. Not because i didnt like the answers.

Thanks
Ric