Fuel system questions

Just installed a new sending unit in '75 CJ5.
Was hoping to clean up some of the plumbing, just want to make sure this is going to work before I put the body back on it...

2 Fuel lines come out of the side of the tank, to/from rollover check valve and/or carbon cannister?
Can I plug them up?

Sending unit has 2 lines as well, I have new line to run to the carb, the 2nd line I'm guessing is return line from carbon cannister?
Can I plug it?
Should I leave one open as a breather and put some type of 1 way valve on?


Will I be getting enough fuel to run a Holley Truck avenger 4Brl (670CFM) sitting on an Edelbrock Performer(non egr) intake? (AMC 360)
Holley says the recommended fuel pressure is 5-7 psi.


Thanks.

 

I wouldn't see any problem with plugging the two vapor separator lines from a performance standpoint, but that means disabling emission controls which may get you in trouble. The second line on the fuel sender is for a return from the fuel pump. You can plug it.

You should have no problem feeding a mild 360 with the stock 5/16 fuel line. If you are running enough power to actually need all of that 670, you may need to upgrade the whole fuel system to 3/8" (including the sending unit/fuel pickup.)

 

If you plug the vapor recovery lines, you'll need to use a vented gas cap to replace the venting that went through the canister.

If it were no great difficulty to keep the canister, liquid check valve and plumbing, I would. The vapor recovery system vents your tank and keeps liquid fuel from seeping out of a replacement vented cap, or from pouring out if you go wheels up. There's no performance penalty with vapor recovery, and very little maintenance.

I'd keep the fuel return line too. It's not part of the vapor recovery system. The proper fuel filter has a fitting for it, and its supposed to lower the temperature of the fuel in the lines to avoid vapor lock. Again, no real performance penalty, and a real advantage if the line is already there.

This plumbing actually does something positive for you, and I'd suggest you resist the urge to remove it just for the sake of tidiness.

 

My '75 doesn't have a fuel return line, that's why I suggested just plugging it. different applications, different answers

 

Good info, thanks.
I think it was 3/8's line I couldn't get to fit onto the sending unit. 1/4 fits fine, but might be too big I think...