Garage gas smell

[inri]

Hi all,

Recently been parking my '69 plymouth in the attached garage and there is a very strong gas smell. IF I open the garage the smell permeates in about 10 minutes but it's very strong. Is there something I can do to lessen the odor and or eliminate it? My gas cap is vented and so it the back of the gas tank with a rubber hose.

Thank you.

 

[pnora]

Find the leak. Follow every inch.

 

[topside]

Yup - shouldn't be an aroma unless there's a leak or open container.
I have 5 cars & 4 filled fuel jugs in my front shop, and 2 trucks in my back shop, and I have no gasoline aroma in either.

 

[Fran Blacker]

Agree a leak but also you maybe boiling gas in carb. Experiment if you run an AFB/AVS if you have electric fuel pump switch it off or pop the fuse to run car out of gas. No electric pump pinch off a rubber to run carb out of gas. Pump the gas pedal to get as much gas out of carb before it stalls. Probably won't work on a Holley, secondary fuel bowl.

 

[Dave6T4]

Your smell is likely fuel evaporating from your warm carb after a drive. Today's fuel is much more volatile than the fuel that our old cars' system was designed for. Another related problem is poor starting after the car sits for a while because the fuel has left the carb bowl. The fuel pump now has to pull gas all the up from the tank to replenish the carb. My own 1967 R/T has always suffered from these conditions; stinky garage and prolonged starting.
This past summer, I had the top end of my 440 apart for a repair. When I was reassembling it, I took the opportunity to block off the heat riser ports from the heads to the intake manifold. Although doing this eliminates much of the heat to carb, I only drive my car in warm weather and the carb has an electric choke on it, so it is not dependant on manifold heat to operate correctly. Since doing this modification, my car no longer stinks up the garage with fuel evaporating from a hot carb. I also find my engine starts much better, even after sitting one or two weeks, because there is still fuel in the carb.

 

[Runcharger]

Gas filler neck grommet.

 

[sam dupont]

My last daily driver did that, it was a rust hole on top of the tank. Ask how iI found that one

 

[#41]

If it's very strong, probably the filler grommet to the gas tank. That has been my experience. It can leak slowly and soak the insulation on top of the tank without dripping on the ground.

 

[Fran Blacker]

Your smell is likely fuel evaporating from your warm carb after a drive. Today's fuel is much more volatile than the fuel that our old cars' system was designed for. Another related problem is poor starting after the car sits for a while because the fuel has left the carb bowl. The fuel pump now has to pull gas all the up from the tank to replenish the carb. My own 1967 R/T has always suffered from these conditions; stinky garage and prolonged starting.
This past summer, I had the top end of my 440 apart for a repair. When I was reassembling it, I took the opportunity to block off the heat riser ports from the heads to the intake manifold. Although doing this eliminates much of the heat to carb, I only drive my car in warm weather and the carb has an electric choke on it, so it is not dependant on manifold heat to operate correctly. Since doing this modification, my car no longer stinks up the garage with fuel evaporating from a hot carb. I also find my engine starts much better, even after sitting one or two weeks, because there is still fuel in the carb.

Did you put in a Phenolic carb spacer? OP should put one on also. MO

 

[PlymCrazy]

Check for leaks. If none are found I’d suspect boil-off as others have mentioned.

I have (3) Eddy carbs that all have a noticeable gas odor after they’re hot. I’ve concluded it’s due to boil-off. Dissipates after a short while. It’s not too annoying as the cars are parked in a larger space.

But I’d consider a phenolic spacer myself if the boil-off odor was an issue to me.

 

[ckessel]

Some time back on one of many posts about vapor lock issues, one of the gents who is also a resident of the PRC like me, found that the California swill boils at 150*. What temp does the engine run at and how hot is it under the hood when running? Think about that along with looking for leaks on the rest of the fuel system. When my 65 was a driver back in 13-16, I could hear the fuel boiling in the tank after a 30 minute or so drive. Has 3" TTI exhaust that runs right by the tank on its way to the rear bumper.

 

[BMosely]

My first marriage house was a cookie cutter starter home where they put the gas water heater in the garage exposed, using the garage for combustion air. How this met code I am not sure as any flammable liquid in the air now had an ignition source. Anyway, my workbench had to go in this space and as we know it is weekly use of highly flammable products. I installed a bath vent fan on the bench upper shelf and piped it outside. Now when I worked the vapors went directly out and away from the flame.
A 50 cfm bath fan in your garage might go a long way to keep it vented and I also liked in the summer it dumped the car heat instead of it fighting the house a/c. You can whip the fan with a cord so you just plug it in or put it on a motion run time sensor.

 

[xs-ivv]

If it is boiling the gas out of the carb try one of these insulators under the carb. It worked well for me.

 

[sam dupont]

If it's boiling, would one be able to take it for a run, shut it off, pull the air cleaner and see or hear something?

 

[pnora]

boiled gas is gone to the atmosphere, and gone quickly. Raw gas is another story. Does the poster know the difference? Beer farts or the dog can also play into this.

 

[AR67GTX]

If it's boiling, would one be able to take it for a run, shut it off, pull the air cleaner and see or hear something?

Yes, you should see the throttle plates getting wet. It may take 5 minutes or more for heat soak to take effect. I’m more familiar with this on Holleys but Carters and Edelbrocks will do the same. I’ve seen it bubbling and dribbling out of the accelerator pump shooter and the boosters on Holleys. The odor of gas, percolating off or especially baking on a hot surface is much different to me than just plain, gas odor from a fuel line drip. Percolation or a gas seep down on a hot intake or something is more pungent and lingering. A simple gas drip on a cool surface is usually evaporated and gone pretty quickly.

 

[inri]

Thanks for the replies all. Should have mentioned this is a modern Hemi swap efi with new gas tank/pump etc. I was thinking the vented gas cap should be changed to non-vented?

 

[PlymCrazy]

Thanks for the replies all. Should have mentioned this is a modern Hemi swap efi with new gas tank/pump etc. I was thinking the vented gas cap should be changed to non-vented?

How much fun was it watching us throw carb related answers at it?

 

[pnora]

How much fun was it watching us throw carb related answers at it?

No wonder why doctors cut off the wrong leg.

 

[PlymCrazy]

No wonder why doctors cut off the wrong leg.

Agreed