Anyone remove their vapor return line?
Thread Starter
Instructor
Joined: Apr 2000
Posts: 165
Likes: 0
From: Vacaville California
Anyone remove their vapor return line?
I have a new engine, aftermarket fuel pump, etc. and wish to leave the vapor return line off the car for simplicity's sake ('75). My engine builder said I should have no problems without it, as I have a large pump and live in a mild climate (WA). He said unless it's 110* I shouldn't see vapor lock. Well, the body's off right now and once it's back on I don't think I could get one in if I tried: so it's now or never.
Have any of you eliminated your vapor return line, and are you having problems with vapor lock?
Have any of you eliminated your vapor return line, and are you having problems with vapor lock?
Burning Brakes
Joined: Aug 2004
Posts: 971
Likes: 7
From: roanoke va
i would leave it on. you never know where the future will find you and if you need to pass emissions (later) it will need to be there. i hate to have to do something over and once i get my body back on the frame i do not want to remove it for any ones money or stupid laws.
Safety Car
Joined: Jul 2002
Posts: 4,269
Likes: 3
From: St. Charles IL
Cruise-In 5-6-7-8-9-11-12 Veteran
A CI-6 Car Show Winner
Are you talking about the vapor return line or the fuel return line? There are 3 lines total. The vapor return line is basically for emissions control and won't be a operating problem if you use a vented gas cap.
Edit: If you are running a electric fuel pump and it's located at the tank you won't need a fuel return line. People do seem to get in trouble with large volume fuel pumps located at the engine because of the vacuum they create on the fuel line causes the fuel to vaporize in hot weather. Vacuum will lower the vapor pressure of the fuel, so if you send it through the line under pressure the problem is gone. You would then need a fuel pressure regulator located as close to the carb as possible.
Edit: If you are running a electric fuel pump and it's located at the tank you won't need a fuel return line. People do seem to get in trouble with large volume fuel pumps located at the engine because of the vacuum they create on the fuel line causes the fuel to vaporize in hot weather. Vacuum will lower the vapor pressure of the fuel, so if you send it through the line under pressure the problem is gone. You would then need a fuel pressure regulator located as close to the carb as possible.
Last edited by Big Fish; Nov 13, 2004 at 06:46 PM.
Race Director
Joined: Apr 1999
Posts: 15,147
Likes: 477
From: NM
I'm confused, how does the vapor return line have anything to do with vapor lock????
The vapor return line takes fumes from the tank forward to the charcoal canister for storage until they can be sent to the carb to be burnt.
tom...
The vapor return line takes fumes from the tank forward to the charcoal canister for storage until they can be sent to the carb to be burnt.
tom...
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by MotorHead
Easiest solution is to leave it there and plug it up 
Safety Car
Joined: Jul 2002
Posts: 4,269
Likes: 3
From: St. Charles IL
Cruise-In 5-6-7-8-9-11-12 Veteran
A CI-6 Car Show Winner
Originally Posted by Tom73
I'm confused, how does the vapor return line have anything to do with vapor lock????
The vapor return line takes fumes from the tank forward to the charcoal canister for storage until they can be sent to the carb to be burnt.
tom...
The vapor return line takes fumes from the tank forward to the charcoal canister for storage until they can be sent to the carb to be burnt.
tom...
That's why I asked him if he might be talking about the fuel return line 
Last edited by Big Fish; Nov 15, 2004 at 12:19 AM.
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