Going EFI-Need advice on fuel hose selection

[jbojo]

If you do use the vapor as a return, the tank will still need a way to vent pressure changes in the tank and allow air in to replace the fuel used

I installed another dedicated return fitting in my set up, and ran soft lines to just past the pump and at the return fitting, as well as the vent line for about a foot or so.

Engine has soft fuel lines as well. In between is metal pipe.

To prevent a vacuum from occurring in the gas tank because it's a closed system now I made a small vent hole in my gas cap. This seems to have worked in my system.

 

[Don C]

I like the looks of the FiTech fuel command center, with the pressure gauge, plus a lot lower cost than the Edelbrock surge pump.

However, I can see a potential problem with teeing into the existing vent line. If not done correctly the vent for the fuel tank can be compromised, which would result in the fuel tank trying to vent through the FCC, creating a vacuum in the fuel tank and the FCC. I have to wonder if this is what's happening to the guys on the Corvette forum. Personally I would (will) consider a separate vent line to the fuel tank for the FCC. That way if the float/needle valve in the FCC gets stuck the fuel will just return to the tank.

 

[tony-muscle]

If you do use the vapor as a return, the tank will still need a way to vent pressure changes in the tank and allow air in to replace the fuel used

I installed another dedicated return fitting in my set up, and ran soft lines to just past the pump and at the return fitting, as well as the vent line for about a foot or so.

Engine has soft fuel lines as well. In between is metal pipe.

To prevent a vacuum from occurring in the gas tank because it's a closed system now I made a small vent hole in my gas cap. This seems to have worked in my system.

John, I am curious about the vent hole in the cap. Where in the cap did your drill? I am considering my options for fuel pump so the ability to use the charcoal line as return is appealing. I am considering the BobbMc PowerSurge pump, so the vent line won't be a "full" return line, just excess gas, I guess.

Also, you said you drilled the vent orifice on top of the tank. Without drilling, would the cap allow gas to flow back into the tank, or is it a one way system?

Another possibility is to add a second tube to the sending unit to use as a return line, but that implies running a whole new hose from the engine bay all the way back to the tank.

 

[71XR7VERT]

I ran steel lines underbody, except for the tank connections and engine connections, where I used fuel injection hose.

 

[jbojo]

If you do use the vapor as a return, the tank will still need a way to vent pressure changes in the tank and allow air in to replace the fuel used

I installed another dedicated return fitting in my set up, and ran soft lines to just past the pump and at the return fitting, as well as the vent line for about a foot or so.

Engine has soft fuel lines as well. In between is metal pipe.

To prevent a vacuum from occurring in the gas tank because it's a closed system now I made a small vent hole in my gas cap. This seems to have worked in my system.

John, I am curious about the vent hole in the cap. Where in the cap did your drill? I am considering my options for fuel pump so the ability to use the charcoal line as return is appealing. I am considering the BobbMc PowerSurge pump, so the vent line won't be a "full" return line, just excess gas, I guess.

Also, you said you drilled the vent orifice on top of the tank. Without drilling, would the cap allow gas to flow back into the tank, or is it a one way system?

Another possibility is to add a second tube to the sending unit to use as a return line, but that implies running a whole new hose from the engine bay all the way back to the tank.

I drilled a small hole in the cap to allow air to enter the tank so there would not be a vacuum created as the fuel is drawn out of the tank and I used the smallest drill bit that I had. On my car the top of the tank has a cap to return fuel vapor from the air cleaner to the charcoal can and back to the tank, This line is already plumbed so it made a perfect fuel return line for me. I did not have to modify the tank in any way to get this done and it seemed a logical choice for me. I now have 1500 miles on this system with no issues so it seems to be working. MY EFI system is for cars up to 500hp.