[Pinion]

I am using a 4-5psi electric fuel pump in line before the mechanical one. The only reason I am still using the mech one is that it has a return line to the tank. Well my mech. one finally crapped out the other day and I was wondering how the return line functioned in the mech pump. Does it just dump back to the tank once the operating pressure to the carb has been met?

By this I am asking if I could just cut the line a foot or so after my electrical pump, install a "T" fitting and then hook the return line from the stock pump into that? Does it need some sort of check valve on it?

[Poser]

if your engine actuated mechanical fuel pump has failed, putting fuel through it, may cause it to leak into the crankcase, diluting your engine oil…

[Pinion]

Thanks, I know that and just proved it after dumping out the oil. I dont think I got too much in it regardless. Any ideas about the return line though? Im going to take the hoses off the mech pump and leave it on as a block off plate for now until I get one made up.

[Pin_Head]

Only the later stamped top mechanical pumps had a return line. If your carb has a fuel return line (up to '78) then just hook the carb return line to the return hose. If you don't want to run a mechanical pump (no need for 2 pumps), just block off the mounting boss and plug the return hose. Just make sure that your tank is properly vented for what ever year is appropriate.

[Pinion]

Unfortunately Im using the Holley 3 fiddy or whatever so it doesnt have a return line. Their literature says that it needs around 4-5 psi and that is what my pump puts out for max pressure. Under idle though I could still hear gas trickling back into the tank, so I dont know what to think. I do know however that I prefer the electric pump. I dont have to worry about it dumping gas into the oil pan if it fails, and its pretty sweet to jump in and turn the key and have it start up almost as if it were fuel injected.

I have an Aisin carb I rebuilt from one of my old 60's, but I dont have any of the linkages so it sits on a shelf in a plastic bag. :(

[clemson55]

You don't need to get a block off plate made you can go buy one from TPI4x4.com and I'm sure some of the other cruiser suppliers have it to. I just got mine there since they are close to home, got it in 2 days.