Return Line Question

[kingcolbert83]

I have a 78 regal. It has two steel lines coming from the tank up to the engine bay. Is the smaller one the return line or canister line? I thought I took it off the canister but I cant remember. I ask this because I have a buick 430 that is a return style pump. I don't recall my sbc having three lines which is why I am thinking it was for the charcoal canister but I could be wrong. The line is factory and the one I am talking about is on the driver side, right next to the steering box.

If this line is for the charcoal canister, what are my options for the return line. Can't move the car till I get that situated.

 

[84cutspreme]

Hey, I know inline tube & the right stuff sell all the lines. I had 3 lines coming out of the tank on all my g-bodies. There is the feed line, the return line & vapor line. Vapor line is the one on driver side that goes to canister. Return line you only need if you have 3-line pump or if you encounter vaporlock. The feed & return line run up the passenger side. I just purchased lines for my car from inline tube. The lines are almost exact from factory, they bend them a little different. All in all I was happy with the lines...they also sell them in oem steel or in stainless. If I remember correct feed line is 3/8, vapor is 5/16 and return is 1/4. They also sell 1/2 feed lines too. They even sell the short lines that run from the tank to the frame behind rear end.

 

[Bonnewagon]

All cars have a vapor line but not a return line. Mostly V-8 AC cars had the return line to avoid vapor lock, but not all had it. You can add a return line but that involves dropping the tank and soldering a steel line in at the top plate of the fuel level sending unit assembly. There's usually a spot allready there next to the fuel and vapor lines to use. Otherwise the pump can be replaced with a non return type. Do not attempt to plug the return line fitting, the pump will flood your carburetor. To get the car running right now, try plumbing the return line right into the supply line with a "T" fitting so the excess fuel goes right back to feed the pump. Just don't leave it like that permanently.

 

[84cutspreme]

You can also replace the sending unit to a 3-line setup like I did just in case, because I had my tank out. So if I need a return line now, just gotta run it up the side of frame. Dorman makes it, Part # 692-089. It ran me $70 from summit, GM is astronomical in price. The only thing I would suggest is buying the lock ring from GM because the Dorman one is cheaply made.

 

[78 salon]

My 78 cutlass only has 2 lines also. If you're not using the cannister, use the vapor return line as the return line off of the pump.

 

[Bonnewagon]

The purpose of the charcoal cannister is to collect gas fumes and store them until the car starts and burns them off. For that reason the gas cap is non-vented. On a hot day, with no vent, the gas in the tank will expand and push right to the carb flooding it and diluting your oil. I don't understand why people yank it out when it actually serves a purpose and has nothing to do with performance.

 

[hotrodpaully]

I have 81 cutlass that had diesal motor in it putting 350 chevy carb in has suppy and and return line but no vent .
return line runs below fuel level in tank so cant use that for vent so planned on plugging return line and trying to find vented gas cap or would i be better off drilling hole in top of tank and adding vent line??

 

[84cutspreme]

The purpose of the charcoal cannister is to collect gas fumes and store them until the car starts and burns them off. For that reason the gas cap is non-vented. On a hot day, with no vent, the gas in the tank will expand and push right to the carb flooding it and diluting your oil. I don't understand why people yank it out when it actually serves a purpose and has nothing to do with performance.

I can concur with that...I installed my tank back in my car with a new 3-line sending unit with vent, return & feed. I did it just in case I need a return down the road, don't know if I'll encounter vaporlock. My dumbass left both the return & vent capped because it's been sitting till I finish up build. First hot day we had (Blessing in Disguise), tank pressurized and sent fuel up to carb...I had to drain oil and air out crankcase and other bullshit cleaning. It was a blessing only because the chrome dual feed line I purchased was a piece of sh*t so it was leaking. So I returned the line and got a new one, not chrome and even went and tested it this time before installing it.

 

[Bonnewagon]

It's not that hard to add a line. Worst area is the rearaxle. They put the lines on the frame and then dropped the body onto it. I just go around the impossible areas, and if it's too much, you can jump the bitchy spot with rubber hose. The sending unit usually has a spot for the 3rd line. I just drill it then solder in a piece of tubing.

 

[Peter]

resurecting this topic

i am using a 2 line system. regular feed line but am using my vapor line as my return line. so can i get a vented cap or edit my cap to be vented (without having gas sloshing everywhere)

chances are i am going to pick up a locking gas cap (prevent the haters from ruining my engine) and drill some tiny vent holes unless i find something that meets my needs