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???

 

The mechanical pump has a pressure relief spring built into it. It will hit 6 PSI (or whatever it's rated for) and won't pump any more.

The tank must be vented to prevent too much pressure from building up (and prevent VACUUM from building up as the fuel level drops). Typically, the line that used to go the original charcoal canister will perform this function adequately.

 

What is the line with the little filter on it hanging just in front of the drivers side rear wheel for????

and if does not do any pressure relief I quess you are telling me I have to pull the tank down and open up the line that used to go to the charcoal filter.????

 

you could of just put a fulepress reglater in. if you did this you would not have had to drop the tank. the reg coast around 70 to 100$ this would reduce the 40 some ood pounds to 6-8 pounds pluse it is fully adjustable if you are going to be adding NOS in the furture i would install a other line for a new pump just for the NOS.All in all the think i would of dun was got the reglat and ran it to the carb.then i would cap off the block where the mican pump would go

 

I Decided to go with the mechanical fuel pump because I have already had to change two of them in the tank. I drove this car for 8 years before we started to restore it. The pump in the tank parts only cost me about 250$ at Canadian Tire. Can't imagine what a GM pump would have cost.

Ric

 

The "filter thing" is a vent. As long as it's not plugged and you have a return line back to the tank then you're set, the extra fuel just gets returned.