Fumes

[Apperloo]

Hi, I am a newbie herewith a new to me 30A pu. First oldtimer for me.
Parked in the garage she gives off a lot of gasoline fumes, like evaporating gas.
No visible drips on the floor, although there is residue under the carb.
I have the under dash pet cock turned off. I have checked the gasket on the cap,it may be hard, but it looks like it is seating well.
Am I missing something?
Thx,Leo
ps, I may have a few dumb questions....

[ryanheacox]

Most likely culprit is gas weeping/dripping out of the carb. Many have this issue and many cars have shutoff valves that don't seal well either. Your carb may be weeping just enough to cause that residue but it evaporates before it has a chance to drip?


Other culprits can be the sediment bowl, the steering column mount under the tank and possibly the gas gauge. Pretty much after 90 years gas can leak from anywhere. It's a simple system though, you'll find the source soon enough.


I should also mention, since the tank vents to atmosphere along with the carb bowl you may get some gas smell even when everything is functioning as it should. Not a lot of fumes though.

[Tacoma Bob]

Welcome! a photo of the carb side would be helpful. Could be several things. Do you know which carb you have? Sounds like you may have gas weeping between the carb halves. (gasket). Please watch for gas puddles on the floor. Lots of possibilities. Others will chime in but like I say a photo would help.

[mike657894]

the under tank petcock is brass on brass and can leak with scratches. I had to clean mine up. There are affordable replacements. The needle and seat are metal on metal and prone to some weeping of gas. if you have the tank drained clean or replace your pencil filter in the iron sediment bowl. The bottom threads out. use a crescent wrench(or appropriate size) on the flats above the bottom spinner. I think the spinner is a drain but mine is locked up.

[Mulletwagon]

Probably a slow leak at the shut off valve. You can confirm a leak by disconnecting the fuel line at the carb and use some flexible tubing to direct any flow into a bottle. Had the sme problem and discovered the valve leaked about two ounzes overnight. New valve fixed the problem.

[Apperloo]

Sponsored Links (Register now to hide all advertisements)

pic as requested:

https://www.fordbarn.com/forum/attac...1&d=1566226305

Sorry, having a learning session on uploading pics

[History]

It could be leaking at the glass sediment bowl gasket. Just a swipe with your finger in that area should say. Snyders has the gas cap gaskets cheap if you need one. ((((It could also be running really rich because you have an air cleaner on it. Could that saturate things to the point he gets the gas smell??))) David Renner told me not to run a filter as the carburetor was designed NOT to have one and will run too rich. They can be modified to have an air filter, according to Dave.

If you find your shut off valve, inside and under the gas tank has to be removed, you can jack the car up so what gas that's in the tank flows to one side. Some genius on here posted that idea. It's easy to forget simple things sometimes.

Don't forget to check around the gas line fittings as they could be weeping some.

[Curtis in MA]

Where are the fumes strongest?
Mine leaked from the gas gauge so fumes were strongest inside.

[California Travieso]

Apperloo,

Welcome to the Barn. Same thing happened to me. When we bought our Roadster I brought it home and parked in the garage. Next morning my wife freaked out with the gas smell.

One of the guys in our Model A Club suggested that when I drive it into the garage, turn off the gas valve and leave the car running until all the gas is drained from the carburetor and the engine stops running.

One very important thing, don't forget to turn off the key. I forgot to turn the key off once and ruined my battery.

I would try that before trouble shooting other problems.

Good luck,

David Serrano

[Apperloo]

no fumes inside. Definitely from the exterior

[Tacoma Bob]

OK thanks for posting pics. So you have a Zenith carb. Also looks like crud in the glass sediment bowl. I use Wix filter #33039. Do easy stuff first. No sense tearing into stuff. Remove the air filter. If the carb is running rich the carb screen (filter) may be "water" logged with gasoline. As mentioned run you finger around all the fittings and the carb itself. Does the gas smell fresh or like old varnish?

[Ernie Vitucci]

Good Morning and welcome. Bratton's makes a very fine secondary fuel shut-off with a quarter turn modern ball valve. I love mine. It is part number 13350 and costs $61.05. Bratton's phone number is 800-255-1929. Enjoy your new 'A'. Shut this valve only after installation. Leave the original valve on all the time if it does not leak. Run the carburetor dry...takes a couple or three minutes and things will not smell so much. Check around the fuel gauge with a piece of toilet paper to see if it is weeping. Walt Bratton has the wrench and the gaskets to repair the gauge if it is weeping. Lots of other suppliers as well. Lots of advice here on the barn. Ernie in Arizona

[lorenallen]

I had the same problem and it turned out to be the shut off valve under the dash even though the valve was less than 1 year old. I changed the valve and the problem went away. I always shut off the valve and let the car quit when it runs out of gas. Have not had any leak problems since. It only takes a small amount of gas to smell up the garage.

[Apperloo]

Wow, Lots of help, advice and good ideas on this forum . Thanks.
After work I pulled the sediment bowl, and immediately the problem was apparent. One big drip 1 to 2 min apart. I suspect by morning the bowl will be full.
I will order and replace the gas cock. Hopefully just a re+re
On another note, is there some suggestion to remove the airfilter .....

[MVal]

Don't think anyone has mentioned this but having a gas leak in a garage can be a major problem if a source of ignition is there too like a hot water heater. Park it outside until the leak issue is solved so you don't have a much larger problem.

[ryanheacox]

Yup, that’s exactly what my old shutoff did. Would run the car out of gas and 2 hours later I would be dripping gas.

I will argue that regardless of the condition of the shutoff valve, the carb should not leak gas. The float valve in the carb should be able to seal off the flow of gas.

However, a working shutoff will buy you some time before you fix the leaky carb.

[History]

I agree Ryan. His leak could have been gas oozing around the sediment bowl gasket as it appears his float valve was working as it wouldn't let gas flow back into his sediment bowl.

Originally Posted by Apperloo

On another note, is there some suggestion to remove the airfilter .....

David Renner, of Renners Corner where I purchased "flow tested" jets for a carburetor like yours told me to remove mine. He explained that originally there wasn't an air filter on these carbs. They were designed to run without one and when one is placed on the carb it now changes the air flow to less with more gas. The restriction in air flow is similar to having the choke partially on.

I haven't even started my car since I got it as I've been cleaning the fuel system and going over things ,brakes, transmission, electrical,,,,,,,,,,,. But what he said makes sense. He can take your carburetor and modify it to run as it should with an air filter. I'm going to try mine both ways and see what difference it makes, while I don't doubt his statement at all.

[Apperloo]

In cruising around thru the parts list, now that it has been confirmed to be a Zenith carb, a new modern needle kit #A-9564.
States it is designed to prevent a leaky carb. Is that only while running or?

[ryanheacox]

Renners is the go to place for everything carb related on a Model A. I have flow tested jets from them in my car.



If you aren't driving on a bunch of dusty dirt roads I agree with them about air filters.


Apperloo, did you notice any leaks/weeping around the sediment bowl or just around the carb?

[Apperloo]

Only around the carb. And still.
Even with the sediment bowl half empty which baffles me a bit.

[ryanheacox]

Those old carbs do like to leak when given the chance. If you're up for it, it's relatively easy and cheap to rebuild the carburetor and be confident that it will perform well and be leak free. There are a ton of articles about rebuilding them too.


Can you pinpoint where it's leaking from? Is the throat of the carb wet or is it just the bottom?

[Apperloo]

Thanks eh
24 hrs and the sediment bowl is 1/2 full.
I cleaned up around the carb this morning, and all is still dried up.
It was wet on the bottom.
I have a new gas valve to install, so will change that first, and if all goes well and the leaking stops, it will be onto the next issue

[History]

These carburetors are pretty simple if you're mechanically inclined. I'm glad I accepted the challenge of rebuilding mine. Of course I haven't ran the engine since then but I'm confident it's done correctly. I'm sure there's fellows who could fine tune to perfection and I'll admit I'm not one of them.

If you just need a gasket or a complete rebuild, I say go for it. Lots of information on this site.

If you do rebuild yours make sure you are carful when you separate the halves as the Venturi can become stuck in either or both sides. Mine was broken in two pieces and had been used that way as one side was sanded smooth at the break.

[Apperloo]

It’s been a fair number of years, too many, since I’ve rebuilt a Holley double or carter carb, but I will tackle whatever needs doing, at least once
Any thoughts on using Teflon tape or "?? on the pipe thread end of the gas valve threading into the tank? I suspect stock did not use any sealant ....

[30 Closed Cab PU]

Originally Posted by Apperloo

It’s been a fair number of years, too many, since I’ve rebuilt a Holley double or carter carb, but I will tackle whatever needs doing, at least once
Any thoughts on using Teflon tape or "?? on the pipe thread end of the gas valve threading into the tank? I suspect stock did not use any sealant ....

If using Teflon tape, use the gas/oil resistant type. I believe it is yellow. Not commonly found, may have to search for it. When wrapping it on the shutoff threads make sure the tape does not extend past the threads, which can cause the tape to shred and get into the gas supply.

[30 Closed Cab PU]

Sponsored Links (Register now to hide all advertisements)

Here is links on Zenith carbs. Everythings you wanted to know, and maybe more than you want to know.
https://www.modela.org/


Les Andrews books, and the Rex Reheis Way written by Gordon Biggs are also excellent books.

[Apperloo]

[QUOTE=30 Closed Cab PU;1790260]Here is links on Zenith carbs. Everythings you wanted to know, and maybe more than you want to know.
https://www.modela.org/

Great , that is a lot info for a simple system. Saved to my dropbox. Thanks

[Synchro909]

To seal any thread, I use a small dab of Permatex No 3 Aviation gasket sealer. Fuel and oil don't affect it and the thread can be undone easily later. I use it on the sump and gearbox plugs, fuel lines, diff housings - everywhere. Similar stuff was around when I was a kid so it has stood the test of time.
Clean up is with a little mineral turps on a rag.
No more leaky joints anywhere.

[Apperloo]

I let it drip last night and for sure it is seeping thru the area above the float.
The A has been pretty much sitting for 20 years, so I’m sure that gasket has gone bad.
In the job jar

[ryanheacox]

I recently changed all the gaskets in mine and put in a viton tipped float valve. No more leaks for me.

[30 Closed Cab PU]

Originally Posted by Apperloo

I let it drip last night and for sure it is seeping thru the area above the float.
The A has been pretty much sitting for 20 years, so I’m sure that gasket has gone bad.
In the job jar

If you are referring to the gasket that is between the bowl and the upper carb body, if the float valve is set and working properly gas does not reach that high in the float bowl, even with a bad gasket it should not have a leak.

[Apperloo]

Originally Posted by 30 Closed Cab PU

If you are referring to the gasket that is between the bowl and the upper carb body, if the float valve is set and working properly gas does not reach that high in the float bowl, even with a bad gasket it should not have a leak.

Thanks, I will check that