Need some quick help with a fuel pump issue

[AirSpeed]

Trying to replace my fuel pump in my 72 GMC 4X4 with 350/350. I ordered a new one and it has one inlet and two outlets, the one I'm replacing had only two. I just looked under my truck and found a third line running from right under the battery, mounted to the frame then to the gas tank. The end under the battery, mounted to the frame has what's left of a rubber line stuck to it. Is this the return line or is it supposed to go to a charcoal canister? I'm thinking the pump on my truck now is the wrong one and I should reconnect the the unused return line and use the new pump. Is there a reason not to do this?

[slikside]

Originally Posted by AirSpeed

Trying to replace my fuel pump in my 72 GMC 4X4 with 350/350. I ordered a new one and it has one inlet and two outlets, the one I'm replacing had only two. I just looked under my truck and found a third line running from right under the battery, mounted to the frame then to the gas tank. The end under the battery, mounted to the frame has what's left of a rubber line stuck to it. Is this the return line or is it supposed to go to a charcoal canister? I'm thinking the pump on my truck now is the wrong one and I should reconnect the the unused return line and use the new pump. Is there a reason not to do this?

Was your truck made in Fremont, CA, with the AIR "smog" system as well?

My '72 2X SWB was and it came with all of that, and the two outlet fuel pump as well. I can't see my truck right now, but Ireplaced my fuel pump less than a year ago. Yes, there is a fuel vent return line to the tank, and IIRC, that line is 1/4" vs. the 3/8" fuel supply line. So that abandoned line you describe just may be the 1/4" vent return line.

[AirSpeed]

[QUOTE=slikside;6735689]Was your truck made in Fremont, CA, with the AIR "smog" system as well?

My '72 2X SWB was and it came with all of that, and the two outlet fuel pump as well. I can't see my truck right now, but Ireplaced my fuel pump less than a year ago. Yes, there is a fuel vent return line to the tank, and IIRC, that line is 1/4" vs. the 3/8" fuel supply line. So that abandoned line you describe just may be the 1/4" vent return

I'm just curious if it was for a charcoal can or if I should hook it up to the return line, I can't imagine it would hurt anything either way but I've been wrong before! I've looked for drawings of the lines but can't find one that shows where this line goes. Thanks !

[slikside]

I'm just curious if it was for a charcoal can or if I should hook it up to the return line, I can't imagine it would hurt anything either way but I've been wrong before! I've looked for drawings of the lines but can't find one that shows where this line goes. Thanks !

I have the charcoal can as well. I guess its possible that other line goes to it, but I just don't remember it that way. I've always assumed that other line was a return to tank, and I can't go look at it now.

[Sean1985]

My new fuel pump is a single in and out. Works fine. I had that same pump with the return line on mine from the p/o and he just capped the return. I didn't like that so I replaced the pump with a single in and out.

[Jurassic-1]

Originally Posted by Sean1985

My new fuel pump is a single in and out. Works fine. I had that same pump with the return line on mine from the p/o and he just capped the return. I didn't like that so I replaced the pump with a single in and out.

My 72 Blazer has 2 lines but I plugged the 2nd line off and use a 1 line fuel pump. It works fine.

[AirSpeed]

Well I got the new pump installed, used what I think is the return line and it runs great, time will tell if it continues to work. Thanks all!