Fuel tank question

[GerryM]

I'm installing a Sniper EFI on my 1974 Challenger. Before I bought the car it had a blower and the 318 stock motor was replaced with a 340 which is still in it. I've recently moved from San Diego to South Carolina and it vapor locks in the heat down here in the summers. I started searching for the problem and turns out the vent has a plug in it up by the engine compartment. I've heard that's a somewhat common thing with 1/4 mile cars? My question is about the fuel tank and creating a return line which the Sniper requires. There are 4 lines coming out of the top of the fuel tank that go to a canister. Are these 4 lines related to emissions in 1974? And If so, since I'm not worried about emissions, can I use the existing vent line as the return line and install a remote mount vent valve on one of the remaining hoses and just ignore the others? Any input would be greatly appreciated!

 

[rogue]

what are you using for a fuel pump? Personally, i'd recommend ditching the stock tank and getting one designed for FI (eg. from Tanks Inc) with an in-tank pump. They're designed for return and venting considerations.

 

[MoparCarGuy]

Agree with @rogue, the Tanks, Inc. tank with in-tank fuel pump has all of the provisions you need and more. The anti-slosh baffle and a fuel pump sump are major upgrades.
FYI - A return line cannot just dump into the top of the tank as that will seriously aerate the fuel and cause problems. The Walbro 255lph pump from Tanks, Inc. has a return tube (white tube connected to "R" in the pump picture) which puts the returned fuel in the bottom of the tank so no aeration.

Here are some pictures of my Cuda's EFI fuel system. The Walbro fuel pump has a 100-micron pickup "sock". I ran an external Aeromotive billet filter housing with a 10-micron filter and used the 3/8" factory hardline as my return line. The new supply line is 3/8" Earl's VaporGuard fuel injection hose which feed the Holley Pro-Billet regulator at 60PSI and then to the Terminator X Stealth throttle body.

 

[moparroy]

Those 4 lines are vent lines - in the little canister above the rear axle there is a check valve (roll over valve). That to say I do not believe you can use that for return. Inside the tank the 4 lines got to vents in each of the 4 top corners of the tank. The vent line in the engine compartment is supposed to terminate in a charcoal canister. It is emissions related but not performance impacting. The idea is that vapors from the tank can collect in the charcoal canister when the car is sitting and then be drawn out into the engine and burned when the engine is running. It provides a vented tank while reducing gas fumes in your garage in conjunction with the proper gas cap. I rebuilt the little canister and plan to use a generic charcoal canister on mine. For EFI the tank must be vented or pressure will build up. I plan to go EFI also after I get it running on carb - I had been looking at Holley's in tank pump that does not require baffle - apparently uses some kind of surface tension thing to keep a larger sock fueled on the pump in the tank. Read some good reviews. The pump is also returnless - the regulator is on the pump in the tank so the feed line to the front is held at the proper pressure. Interesting story back in the day on my '73 Satellite I removed the charcoal canister - and plugged the line - in hind sight I am wondering if that is why I went through fuel pumps on that car and there was always pressure or vacuum in the tank.

 

[Cratos]

i went with Aeromotive tanks set-up with a return, solved the vaper locking here in florida.

 

[MoparCarGuy]

The Holley and Aeromotive EFI fuel tanks are made by Tanks, Inc. There is additional markup if you purchase from Holley or Aeromotive.