Why do I smell gas???
Thread Starter
Instructor
Joined: Jul 2010
Posts: 103
Likes: 1
Why do I smell gas???
I'm stumped here...'73 L82 4spd Holley SA670
I can start the car and let it warm up in the garage, check for leaks at the fuel pump, filter and all connections and she's dry as a bone. Turn the car off and it's fine. If I take her out for a spin, bring her back home, close the garage door and go back into the garage about 5 minutes later, it REEKS of gas....like someone left glass of gas on the workbench.
I have replace the gaskets, all connections and the fuel line from the filter forward and it still smells. I'm also getting a popping out of the exhaust when I shut it off that just started recently. I've tried to adjust the timing up and down by 6* thinking maybe it would help but it just keeps popping.
Looking for any ideas....
Thanks
Jim
I can start the car and let it warm up in the garage, check for leaks at the fuel pump, filter and all connections and she's dry as a bone. Turn the car off and it's fine. If I take her out for a spin, bring her back home, close the garage door and go back into the garage about 5 minutes later, it REEKS of gas....like someone left glass of gas on the workbench.
I have replace the gaskets, all connections and the fuel line from the filter forward and it still smells. I'm also getting a popping out of the exhaust when I shut it off that just started recently. I've tried to adjust the timing up and down by 6* thinking maybe it would help but it just keeps popping.
Looking for any ideas....
Thanks
Jim
Melting Slicks
Joined: Apr 2001
Posts: 2,030
Likes: 363
From: Lubbock Texas
I chased down a gas smell issue with my '73 awhile back.
Part of the problem was the previous owner had removed the vapor canister and left the vent line from the tank to the canister open which allowed fumes into the garage from the tank. Capping the vent line would have required a switch to a vented gas cap which doesn't really help with the fumes. I installed a new vapor canister and that seemed to help quite a bit except for when the gas tank was full.
I finally discovered the check valve mounted on the drivers side of the tank was cracked and leaking fuel when the tank was full. This check valve goes to the vent line that feeds the vapor canister.
I found the bad check valve inadvertently. I had just filled the tank and pulled into the garage to add a shim to the starter. When I jacked up the passenger side of the car to access the starter, gas started dripping on the floor. Didn't take much to follow the flow of gas to the check valve.
DC
Part of the problem was the previous owner had removed the vapor canister and left the vent line from the tank to the canister open which allowed fumes into the garage from the tank. Capping the vent line would have required a switch to a vented gas cap which doesn't really help with the fumes. I installed a new vapor canister and that seemed to help quite a bit except for when the gas tank was full.
I finally discovered the check valve mounted on the drivers side of the tank was cracked and leaking fuel when the tank was full. This check valve goes to the vent line that feeds the vapor canister.
I found the bad check valve inadvertently. I had just filled the tank and pulled into the garage to add a shim to the starter. When I jacked up the passenger side of the car to access the starter, gas started dripping on the floor. Didn't take much to follow the flow of gas to the check valve.
DC
Team Owner
Joined: Sep 2006
Posts: 31,285
Likes: 4,375
From: Westminster Maryland
Hi Jim,
I think DC could be on the right track.
Check the seal on the gas cap.
Check the vapor separator & hoses/clamps on the tank.
Check the vapor canister and it's hoses/clamps leading to the pvc valve and carb.
Good Luck!
Regards,
Alan
I think DC could be on the right track.
Check the seal on the gas cap.
Check the vapor separator & hoses/clamps on the tank.
Check the vapor canister and it's hoses/clamps leading to the pvc valve and carb.
Good Luck!
Regards,
Alan
Last edited by Alan 71; Oct 30, 2011 at 03:13 PM.
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Also... if you come up empty handed with the emissions equipment... check the rubber fuel lines at the tank. And...look for seepage under the tank straps. I had one oozing under the tank strap for several years before I figured it out.... the tank had a pin hole under a strap and it was high up so it only leaked when I filled the tank.
Thread Starter
Instructor
Joined: Jul 2010
Posts: 103
Likes: 1
Thanks guys....
I replaced the vapor canister last year when I had a minor gas smell and it seemed to eliminate it. I did check the lines into the carb and the line to the PCV valve and they're good. I'll check them all again and check the lines and tank as that's good hygiene. The gas cap is old but it seems to fit pretty snugly on the tank.
Keep in mind that this is a raw gasoline smell like the cap is off the tank and the garage closed up. It only occurs after driving the car and does not happen if the car is just idling in the garage which is what is really perplexing me.
Holley had recommended I increase the squirter from a 32 to a 35 and I wondered if maybe it's dumping way too much gas into the carb and it's drying out after I stop driving it. I've got an email into them to get their thoughts and will update this posting later this week.
Jim
I replaced the vapor canister last year when I had a minor gas smell and it seemed to eliminate it. I did check the lines into the carb and the line to the PCV valve and they're good. I'll check them all again and check the lines and tank as that's good hygiene. The gas cap is old but it seems to fit pretty snugly on the tank.
Keep in mind that this is a raw gasoline smell like the cap is off the tank and the garage closed up. It only occurs after driving the car and does not happen if the car is just idling in the garage which is what is really perplexing me.
Holley had recommended I increase the squirter from a 32 to a 35 and I wondered if maybe it's dumping way too much gas into the carb and it's drying out after I stop driving it. I've got an email into them to get their thoughts and will update this posting later this week.
Jim
Pro
Joined: Feb 2002
Posts: 709
Likes: 10
From: Carlsbad CA
After the car has sat for a short while, check the top of the fuel pump. If the pump is starting to fail, fuel will leak out of the weep hole on the top of the pump. Initially, the amount of gas is not enough to make it to the ground. It will pool on top of the pump.
Melting Slicks
Joined: Apr 2001
Posts: 2,030
Likes: 363
From: Lubbock Texas
I just remembered that I also had an issue similar to yours when I first got my '73. I had problems keeping the floats in the carb set properly and it would overfill the bowls. I ended up replacing both floats (double pumper) and after dialing in the float level, it solved the problem. For some reason it took the engine getting warm before the problem manifested itself.
DC
DC
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Safety Car
Joined: Oct 2005
Posts: 3,570
Likes: 1
From: Algonac Michigan
Because you say that when stationary the smell doesn't present itself but after you drive it the smell is overwhelming, you have a leak at the gas tank near the top of the tank. Or poss. a bad cap on the tank.
Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
I had a similar problem with a strong gas smell inside the car when the tank was over ½ full. It turned out the tank was leaking around the seam and from the top near the filler neck. Here is a thread I started covering the entire sage that actually started because my fuel pump was failing. Trouble shooting that led me to the tank as you will see in this thread: LINK
Burning Brakes
Joined: Apr 2007
Posts: 1,039
Likes: 62
From: Kona Hawaii
Carb Heat Soak?
Fuel Percolation? Carb was heat soaking causing the fuel to percolate out of the fuel bowl into the manifold.Sure sign is hard to start after a shutdown of an hour or more.Was getting a strong gas smell but no leaking anywhere.If you listen closely you can hear the fuel boiling after awhile.Installed heat shield under carb.....Good Luck
Thread Starter
Instructor
Joined: Jul 2010
Posts: 103
Likes: 1
Update....
First, let me thank those who responded. I really appreciated it and after following several of the suggestions I discovered part of my problem....the gas line was loose at the fuel pump.
Now get ready, I know that there are several of you out there who have been dying to use this
so here is your chance....Part two of my problem was my wife filled the lawnmower and left the breather spout on the gas can uncapped.. 
Part three I just discovered tonight while attempting to troubleshoot a totally unrelated issue. (and this is one for the record books!) Although I had already replaced the fuel breather, I did the easy thing which was to simply remove the hoses from the old canister, plug them into the same spouts on the new canister and reinstall it. SURPRISE the a@@ that owned the car before me installed the line that is supposed to run to the PCV valve to the wipers. Needless to say I have some work to do!
Thanks again!
Now get ready, I know that there are several of you out there who have been dying to use this
so here is your chance....Part two of my problem was my wife filled the lawnmower and left the breather spout on the gas can uncapped.. Part three I just discovered tonight while attempting to troubleshoot a totally unrelated issue. (and this is one for the record books!) Although I had already replaced the fuel breather, I did the easy thing which was to simply remove the hoses from the old canister, plug them into the same spouts on the new canister and reinstall it. SURPRISE the a@@ that owned the car before me installed the line that is supposed to run to the PCV valve to the wipers. Needless to say I have some work to do!
Thanks again!
