Fuel Line Leak
Thread Starter
Intermediate
Joined: Mar 2011
Posts: 38
Likes: 5
Fuel Line Leak
I've noticed recently that after driving I smell gas the garage. I've also seen gas sitting on top of the engine as well. After watching it carefully while idling I noticed some small amount of gas come out of the fuel line where it hooks into the carb. I tightened it up, but I still get the smell and see a little gas in spots. I've read that the threads can be messed up easy on the original quadrajets (which this one has). If the threads are good, should I use some Teflon tape on the threads? Thanks! Don
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
Have you seen what happens when you mix gasoline and a corvette ?
If you can see gas, fix your problem before driving further.
Inspect your lines completely from front to back, and repair.
these old gas lines rust from the inside also. (Especially in the middle where you can't see)
Teflon tape is only used on tapered NPT fittings.
(National Pipe Thread) ~ USA
with NPT the threads are the sealing area.
with a Flared gas line, the Flare area,
NOT the threads is the sealing area.
If you can see gas, fix your problem before driving further.
Inspect your lines completely from front to back, and repair.
these old gas lines rust from the inside also. (Especially in the middle where you can't see)
Teflon tape is only used on tapered NPT fittings.
(National Pipe Thread) ~ USA
with NPT the threads are the sealing area.
with a Flared gas line, the Flare area,
NOT the threads is the sealing area.
Burning Brakes
Joined: Jul 2010
Posts: 755
Likes: 8
From: delco pa
I've noticed recently that after driving I smell gas the garage. I've also seen gas sitting on top of the engine as well. After watching it carefully while idling I noticed some small amount of gas come out of the fuel line where it hooks into the carb. I tightened it up, but I still get the smell and see a little gas in spots. I've read that the threads can be messed up easy on the original quadrajets (which this one has). If the threads are good, should I use some Teflon tape on the threads? Thanks! Don
either teh fuel line needs to be replaced or teh carb fitting needs replacing,,,both are available...
i just replaced teh carb fitting on my 68, for teh same reason....
hope this helps.....
Race Director
Joined: Aug 2004
Posts: 10,628
Likes: 132
From: Duvall, WA
the fitting on your q jet has an inverted flare, taht fits teh flare on teh fuel line,,, if either is damaged, or has dirt, etc, in it, it won't seal,,, teh nut only presses teh line to teh carb fitting, so sealing the threads won't help,,,,
either teh fuel line needs to be replaced or teh carb fitting needs replacing,,,both are available...
i just replaced teh carb fitting on my 68, for teh same reason....
hope this helps.....
either teh fuel line needs to be replaced or teh carb fitting needs replacing,,,both are available...
i just replaced teh carb fitting on my 68, for teh same reason....
hope this helps.....
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
I've noticed recently that after driving I smell gas the garage. I've also seen gas sitting on top of the engine as well. After watching it carefully while idling I noticed some small amount of gas come out of the fuel line where it hooks into the carb. I tightened it up, but I still get the smell and see a little gas in spots. I've read that the threads can be messed up easy on the original quadrajets (which this one has). If the threads are good, should I use some Teflon tape on the threads? Thanks! Don
The problem is so common that a self tapping replacement fitting is made to fix it. Available in Help section at auto parts.
Le Mans Master
Joined: Aug 2006
Posts: 7,423
Likes: 1,558
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Inlet nuts.
There are two types of fuel inlet nuts, one has a gasket near the flats and the other has a gasket near the beginning of the threads.
Before you get the self tapping replacement see if a new gasket is the fix.
Before you get the self tapping replacement see if a new gasket is the fix.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Drifting
Joined: May 2008
Posts: 1,647
Likes: 5
From: Roseville CA
Me too. I'm dealing with some fuel line issues now too. I've never worried so much about fuel lines until I got the 71. Just installed the fire extinguisher a few days ago.
Race Director
Joined: Aug 2004
Posts: 10,628
Likes: 132
From: Duvall, WA
I would not use a self tapping fitting to fix it. The two big carb experts that I know, Cliff Ruggles and Lars, both advise against it. Pull it off of the car, take it to a carb shop and let them re-thread the inlet.
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 314
2024 C3 of the Year Finalist - Unmodified
Hopefully your carb bowl inlet is not cracked. Mine was when I first got the car. Going for a ride, smelling gas and then finding all that fuel puddled on top of the intake manifold was enough to freak me out. I also wonder about people who drive around with rubber fuel hoses and plastic or glass fuel filters on top of the engine. 
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
On a Q-jet, there is a piece that screws into the carb body, which holds the filter. It has a gasket, the threads don't seal anything. The fuel line screws into this piece, with a flair, so the threads don't seal anything there, either.
Hold the filter-holder in place with a 1" wrench, I believe, when unscrewing the fuel line, which I believe is a 5/8"? Maybe 9/16"? Anyway, make sure the fuel line itself isn't twisting when you unscrew it.
Once the fuel line is removed, remove the filter holder with the 1" wrench. There should be a plastic gasket at the end of the threads, a fillter element, and a spring that holds the filter up against the fuel supply. Inspect the threads, male and female, on the fuel line, filter holder, and carb body. if everything looks ok, put it all back together, with a new filter and gasket. The filter holder needs to be tight, but remember, the carb body is made of zinc, which is relatively soft, like aluminum, so don't get crazy. Should take care of any leaks in that area.
Scott
Hold the filter-holder in place with a 1" wrench, I believe, when unscrewing the fuel line, which I believe is a 5/8"? Maybe 9/16"? Anyway, make sure the fuel line itself isn't twisting when you unscrew it.
Once the fuel line is removed, remove the filter holder with the 1" wrench. There should be a plastic gasket at the end of the threads, a fillter element, and a spring that holds the filter up against the fuel supply. Inspect the threads, male and female, on the fuel line, filter holder, and carb body. if everything looks ok, put it all back together, with a new filter and gasket. The filter holder needs to be tight, but remember, the carb body is made of zinc, which is relatively soft, like aluminum, so don't get crazy. Should take care of any leaks in that area.
Scott
