Garage smell like gas 74 corvette
Storing my brothers 74 and it has my garage stinking like gas , no visible leaks, fuel tank close to full I pulled the air cleaner off and the carb looked wet from fuel so I put some paper towels down in the carb bowls and pumped the fuel out, this is after its been sitting for about a month now, I think I may have to kick the car out because I spend alot of time in my shop over the winter, and this fuel smell has to go away. just thought I would see if anyone had and clues or suggestions before I kick it out. thanks JR
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JR -
Re: Garage smell like gas 74 corvette
Had a similar problem once on an Olds Ciera. It only tended to happen when the tank was full. Took me a long time to find it but when I dropped the tank it turned out that the top of it was like swiss cheese, I could poke my finger right through it.
My son-in-law's 78 Corvette is showing similar symptoms and even though it is better to store it with a full tank to reduce condensation we are going to have to break that rule this winter. We will address the tank in the Spring.Golf is for those who can't play hockey. -
Re: Garage smell like gas 74 corvette
A very likely problem is the gas filler to tank seal has dried out and needs to be replaced. This can be done by removing the gas door, gas cap, and boot. Then remove the screw holding the filler neck to the tank. Replace the gasket and re-install.Comment
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Re: Garage smell like gas 74 corvette
Thanks guys I will check these things out. JRJRComment
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Re: Garage smell like gas 74 corvette
74 Corvettes came with QJet carburators. Some owners have experienced this carb leaking fuel from the fuel bowl into the intake when the engine was not running after being driven. To stop the fuel you see in the carb you could use something to block the fuel line to the fuel pump. Cut the rubber fuel line to the fuel pump and insert something round into the fuel line to block the fuel from coming out and put a hose clamp around it and let your brother install a new fuel line when he gets the car. I have used a large round steel pin inserted into the rubber fuel line when I block a fuel line. Hope your gas hot water heater is not in the garage.Comment
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Re: Garage smell like gas 74 corvette
Believe a 74 has a charcoal filter tank which uses a small paper filter at the bottom. If the paper filter is bad, fuel venting may occur, but I'm not sure that would happen when stored and not running. Never the less, it's supposed to be a closed circuit system venting back to the tank and not to atmosphere like on out C-1's and C-2's.
Just a thought.
Stu FoxComment
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Re: Garage smell like gas 74 corvette
I'll try this one as my 1974 had a similar problem in 2011. The problem should not be at the carb after a month as any upward fuel line pressure from the pump will have dissipated as will have any residual fuel. But you still have gravity feed pressure to the pump. That should be held in check by the pump diaphragm.
In my case the car ran "OK" but stumbled on fairly brisk acceleration. First thought was ignition but all seemed well. There was a noticeable fuel smell in the garage that I could not figure out. I checked all lines after driving and they seemed OK. Same with the pump. The next few days the smell was still there but no pools on the floor anywhere. But by happenstance I noticed the fuel pump body was sweating for the lack of a better term. A paper towel confirmed a gas film on the body. Not enough to drip but enough to send off fumes.
I was looking at a (small) pinhole flaw in the rubber diaphragm allowing fuel to flow from the bottom of the pump past the rubber to the vent holes in the top and out, albeit slowly. When the motor was hot the fumes just evaporated very quickly. With the motor cold it was just sweat but still produced quite a stink. A new pump fixed the problem (C3 pumps are sealed and not rebuildable).
The pic shows the old pump and fuel wash on it. My NOM 350 has a black block.
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Re: Garage smell like gas 74 corvette
Trying a few things today and also I had just installed a new pump and rubber hoses earlier this summer because of the same problem paul had with his 74 that area is dry as it is from there to the back of the tank, still looking. JRJRComment
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Re: Garage smell like gas 74 corvette
Well I tried. You may be looking at a corroded fuel tank on top as suggested by Norm. If there are no pools under the car it must be an evaporation issue.Last edited by Paul L.; October 27, 2012, 03:51 PM.Comment
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Re: Garage smell like gas 74 corvette
I had a gas smell issue with my 74' during storage a couple of years ago. It was an abnormally warm day. It turned out that I had filled the gas tank quite full and on this warm day the fuel expanded and fuel was leaking out of the bottom of the charcoal cannister. I opened the gas cap to relieve the pressure and the issue was resolved. If your gas tank is quite full you might try siphoning out a couple of gallons of gasoline to see if that helps resolve the issue.Comment
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Re: Garage smell like gas 74 corvette
1974 model year cars all have evaporative control systems, which effectively "seals" the system, so one should never detect fuel vapor once the car cools down.
The EVAP system adds a lot of pipes and hoses to the fuel system, and the hoses deteriorate with time, especially those in the engine compartment that are exposed to high temperatures.
I had a similar problem with my Cosworth Vega some time ago, and I finally found that a hose on the cowl right behind the engine that connects the rear body evap pipe to the front evap pipe in the engine compartment that leads to the cannister had a small split. Given the proximity of that hose to the engine, it runs hotter than any other hose in the fuel system.
I replaced that short piece of hose, and the fuel odor went away.
DukeComment
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Re: Garage smell like gas 74 corvette
This is one of the weak links in the 1970-1974 fuel systems. Plastic fuel tank evaporative control valve #7028035. Often the plastic will crack. if it is in good shape then check the rubber fuel line that connects to it. It will become cracked and pourous. The first thing you will notice is a fuel smell. Later you may see gas residue from dripping and evaporating on the driver side muffler. Many people omit it completely when replacing/servicing their tank. While keeping your car original is noble it is almost imperative to pay attention to these on this date range of C3.Comment
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Re: Garage smell like gas 74 corvette
Not to hijack this thread, but same problem with my '67 L71. Would appreciate any advice. Thanks!Comment
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Re: Garage smell like gas 74 corvette
Ok I did some of the tips from all and I removed 3-4 gallons of gas and noticed also the fuel was getting past the rubber gasket on the gas cap so I flipped the rubber gasket over and for about 24 hours there was no gas smell till this morning and the fuel was again getting past the rubber gas cap gasket, is there that much pressure in the system that it is pushing it past the gasket the fuel in the tank is a good 2-3 inches below the bottom of the tank filler neck what the hay, oh the fuel cap when installed feel tight and sealed.JRComment
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Re: Garage smell like gas 74 corvette
flipping the gasket over is not enough if it has lost it's elasticity. Try a new replacement.Bill Clupper #618Comment
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