I've installed a Fitech EFI system using a Force Fuel canister (#50004) which gets its fuel from the engines low pressure fuel pump and converts it to the 58psi required at the carb. The canister requires a return line back to the gas tank. Question is can I splice into the return line off the engines fuel pump or or can I run a new 3/8" line to the rear of the car and tie it into the 3/8" vent line that is already installed in the tank. The upper passenger side of the tank as a 3/8" and a 5/16" vent line that is ties together with a filter and sits up high above the tank. Do I need both lines or can one be used for the return?

 

The answer to this depends on input from Force Fuel.

Typically these devices have an orifice that limits the amount of fuel being sent back to the tank. Ask them if your 5/16" return line will handle their return flow properly.

 

They say the 5/16" return line off the mechanical pump will handle the flow but that line is currently being used by the mechanical pump. Can I remove that line off the mechanical pump and cap it and use the steel line that runs back to the the tank? Some mechanical pumps have only the feed and supply lines. Mine has 3 lines (feed/supply/return).

Other question is if using the existing return line isn't an option can I use the 3/8" fitting currently being used as a vent and only vent the tank from the 5/16" next to it? They are currently tied together external of the tank with rubber hose tied to a filter.

 

Yes, that is the correct way to handle the return flow. The Force Fuel manages the return instead of the mechanical pump. You only need one return.