New fuel pump...question about 'third' fuel line
Thread Starter
Drifting
Joined: Jan 2012
Posts: 1,908
Likes: 129
From: Fredericksburg Virginia
New fuel pump...question about 'third' fuel line
I have a 1970. I replaced the old GM 3-line fuel pump in my car with a Holley 110 GPH 2-line pump when I completed my fueling project. I currently have the third line (fuel tank vent/recovery line?) capped where it originally tied into the fuel pump.
I have under 5 minutes of run time on this configuration and have pulled the engine out for other reasons. I am, therefore, doing a BUNCH of work to my engine bay, so I thought this was a good time to address the issue/question.
Is there a downside to just permenantly capping this line? Does this serve as the only 'vent' for the gas tank? Do I need to get a different gas cap? Or do I need to figure out how to put a one-way vent on this particular line and bring it up higher in the engine bay?
Stupid questions, I know. Just don't want to screw something up or inadvertently implode my fuel tank. I tried a search, but didn't know the right keywords, so got a bunch of unrelated stuff back.
Thanks for your time!
Keith
I have under 5 minutes of run time on this configuration and have pulled the engine out for other reasons. I am, therefore, doing a BUNCH of work to my engine bay, so I thought this was a good time to address the issue/question.
Is there a downside to just permenantly capping this line? Does this serve as the only 'vent' for the gas tank? Do I need to get a different gas cap? Or do I need to figure out how to put a one-way vent on this particular line and bring it up higher in the engine bay?
Stupid questions, I know. Just don't want to screw something up or inadvertently implode my fuel tank. I tried a search, but didn't know the right keywords, so got a bunch of unrelated stuff back.
Thanks for your time!
Keith
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
I live in the GWN and it does get hot, sometimes, in this neck of the woods. I've had my return line blocked for many, many years without issue using the QJ and two different Holleys. I just recently installed the same pump you have feeding a Holley 650DP Street HP withou a choke. Started every time without issue throughout the summer with a hot or cold engine.
Last edited by resdoggie; Nov 1, 2012 at 12:55 PM.
Advanced
Joined: Apr 2005
Posts: 89
Likes: 5
From: Madison WI
As doggie noted, it's a return line, not a vent line, to keep fuel moving in the system to prevent vapor lock. This summer being a little warmer than usual here in Wisconsin, I got tired of the vapor lock and went back to a stock style pump. I also had the same Holley pump you describe. In the close to 30 years I've had that pump on, it's only been a problem maybe 10 times. But like I said, it's a pain in the butt when it does happen and I just got tired of it.
Dale in Badgerland
Dale in Badgerland
Safety Car
Joined: Oct 2004
Posts: 3,928
Likes: 740
From: Youngstown Ohio
I've had my return line capped for 20 years and never had a problem. I'm running a 170 gph Carter mechanical fuel pump (their version of the superspeedway or nascar pump). Always good pressure and never vapor lock.
Advanced
Joined: Apr 2005
Posts: 89
Likes: 5
From: Madison WI
Like I mentioned, I hadn't had too much of an issue either. Car sits in cool garage out of sun, so the fuel in tank is also cool. But when the car would sit in the hot sun and the temp of the gas in the tank would go up, that was when the problem would occur. IMO, a performance pump is overkill. A stock pump will deliver more than enough fuel for any street application. When I bought my Holley pump, I bought it mostly because it was "pretty".
Dale in Badgerland.
Dale in Badgerland.
Thread Starter
Drifting
Joined: Jan 2012
Posts: 1,908
Likes: 129
From: Fredericksburg Virginia
I appreciate everyone's thoughts and time.
As far as purchasing a 3-line replacement "Corvette" fuel pump, that ship has sailed. Mine wasn't in bad shape or otherwise disfunctional, but it was in 'undetermined' shape. I've been having some reliability issues and have been replacing pretty much whatever I touch with new, usually racing, parts.
I'll probably continue on the path I'm on. If I have a problem with vapor lock, I'll pop my old fuel pump on and/or get a new direct replacement.
I just wanted to make sure I wouldn't screw something up by just capping the return line and going on with my life. If I have a problem with hot-starts, I'll have a direction to head for the fix, at least.
Thanks again!
Keith
As far as purchasing a 3-line replacement "Corvette" fuel pump, that ship has sailed. Mine wasn't in bad shape or otherwise disfunctional, but it was in 'undetermined' shape. I've been having some reliability issues and have been replacing pretty much whatever I touch with new, usually racing, parts.
I'll probably continue on the path I'm on. If I have a problem with vapor lock, I'll pop my old fuel pump on and/or get a new direct replacement.
I just wanted to make sure I wouldn't screw something up by just capping the return line and going on with my life. If I have a problem with hot-starts, I'll have a direction to head for the fix, at least.
Thanks again!
Keith
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Corvette & Porsche 911: How Two Icons Conquered the Last 25 Years
Joe Kucinski
2027 Chevrolet Silverado 1500 First Look: Everything You NEED to Know!
Michael S. Palmer
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski