Return Fuel Line...how important?
Thread Starter
Melting Slicks
Joined: Jan 2003
Posts: 2,713
Likes: 31
From: Shreveport LA
LA Events Coordinator
Return Fuel Line...how important?
I just installed a Holley 80 gph mechanical fuel pump on my 75. It had only two outlets on the pump....one for the fuel line and the other to the carb. The old pump had 3 outlets....the 3rd one was for the return fuel line. I spoke with several seasoned mechanics at the dealership and they told me just plug the return line. So I did just that....and the car runs fine. Then I read some of the threads on this forum for a similar situation and the response was the same thing EXCEPT they added "get a vented gas cap" I looked on the different Corvette vendor sites (Ecklers, Corvettes of America, etc etc etc) and the vented caps end in 1974's model. I looked at my locking gas cap and saw that it was "screw on"....Since I plugged the return line, will the car run without problems and is the screw on cap vented? I am planning on going out of town this next weekend and take the Vette and wanted to make sure there would be no break downs on the road..... 
Any help would be appreciated!! 
Any help would be appreciated!!
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
I have done the same thing as you. I do not have the vented cap either and so far the longest trip I have taken is about 200 miles one way. No problems encountered yet. I would like to get a vented cap just in case though.
Instructor
Joined: Sep 2005
Posts: 241
Likes: 0
From: St Louis Missouri
My 75 is still in pieces, and I’ve just changed to a no return line fuel pump. The return line has nothing to do with venting the tank. There is a vent line that runs along the drivers side of the car up to the charcoal filter. Unless you’ve also capped that off, I don’t think you have to worry about a vented cap.
Instructor
Joined: Jan 2005
Posts: 174
Likes: 0
From: Tampa Bay Florida
Doesn't the return line prevent the fuel from being heated under low-fuel-demand situations? I think Lars had a post on this last month.
I found the thread:
http://forums.corvetteforum.com/show....php?t=1213364
I found the thread:
http://forums.corvetteforum.com/show....php?t=1213364
Last edited by cannonfl; Dec 2, 2005 at 02:39 PM.
Le Mans Master
Joined: Jul 1999
Posts: 9,206
Likes: 17
From: Sewell NJ
On cars with an evap system I don't see how you could cause enough vacuum to collapse the tank. It seems as though once the vacuum in the tank exceeds the vacuum that the engine is making the tank would draw from the evap system. Maybe I'm wrong but I think the system couldn't be completely sealed unless the evap lines were removed and plugged. Now on the other hand, not running a return line may cause vapor lock problems which is what the system was designed to eliminate but that would be more of an annoyance than damaging. Just my $.02.
Last edited by vettfixr; Dec 2, 2005 at 03:32 PM.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Originally Posted by cannonfl
Doesn't the return line prevent the fuel from being heated under low-fuel-demand situations? I think Lars had a post on this last month.
I found the thread:
http://forums.corvetteforum.com/show....php?t=1213364
I found the thread:
http://forums.corvetteforum.com/show....php?t=1213364
I'll never understand why people downgrade their cars with these aftermarket Bubba pumps
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Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
If you are at all worried about the non vented gas cap, just listen when you remove the cap. If you hear a big rush of air... be worried! (Maybe drill a hole in your cap). If not, don't sweat it.
Le Mans Master
Joined: Nov 2004
Posts: 6,434
Likes: 0
St. Jude Donor '07
Originally Posted by cannonfl
Doesn't the return line prevent the fuel from being heated under low-fuel-demand situations? I think Lars had a post on this last month.
Instructor
Joined: Feb 2004
Posts: 210
Likes: 0
From: woodstock ga
If you need a vented gas cap abd yours is not, it taleks about a minute to take the cap appart and take out the guts... when you remover the rubber on way seals you then snap it right back together... no drilling required...
