Gas Blowing Out Exhaust

S

Steve_KS

Member
Hello,

My car has a Stromburg 81 carb, gravity fed, no pump. I've had the car since memorial day and put ~200 miles on it. I'm having trouble starting it the first time each day. I have tried tried many procedures but haven't stumbled on the right one yet.

I've tried pulling the choke out for 1 crank then in while cranking all the way to leaving it out while cranking, but it doesn't start. If I put the throttle half down and crank it wont start. If I pump the pedal a time or two then crank it doesn't start.

What does work is if I crank it over once then push the throttle button to the floor. However liquid gas sprays out of the junction between the exhaust manifold and exhaust pipe like unscrewing a garden hose that's running. Some gas goes out the tail pipe too.

I think the issue is with the carb because I've tuned it up, new plugs, wires, timed it... I freely admit I don't understand the carb that well. Any suggestions?
 

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In my opinion the carb is flooding,dripping gas into the intake,needle and seat not holding gas back.Make sure gas is shutoff at the tank when car is sitting,if it starts easier then you will know it is probably flooding the manifold when just sitting.I would also make sure the float does not have a leak and have gas inside of it.You have a dangerous situation,hope you carry a fire extinguisher!
 
I agree with rocket that you are leaking fuel from the carb to manifold. A lot by your description. You have multiple factors from an internal leak inside the carb to needle and seat issues to fuel shutoff Leaking . Your problem isn’t how to start it at this point but rather resolving the above issues before you have a fire.

I know some of you guys think it’s a huge improvement running the Downdrafts but life is so much simpler and runs fine with a stock zenith for a lot less money.
Just my 2 cents worth.....
Larry
 
The needles and seats and these carburetors will not hold back this new fuel I find it all the time with anything with gravity flow you must turn the fuel off another thing for you to check just to pull the dipstick make sure no fuel is getting into your oil

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The Stromberg carb has an accelerator pump and you really don't need to use the choke. I use to run a 97 and never used the choke. There may be other problems with the carb also but the above is my experience.
I pumped the gas pedal once and it always started.

Dick
 
Try shutting off the gas and running the engine until the carb is dry. Then the next day, turn the gas on, wait a few seconds for the carb to fill, and then try starting it.
 
I had a similar problem with a Holley 94 on my '28 Phaeton. It has always been a hard starter when warm and a little tricky in the morning. I've tried another 94 with the same results.
Last week I had to park the car on a slight angle with the driver's side at a lower rake than the right side. The car sat like this for a few days while I worked on a different car in the garage. After several days, I was smelling gasoline outside and then noticed oil leaking downhill - a LOT of oil with a gassy smell. The bottom of the wishbone and flywheel housing were covered with an oily substance and the dripping was steady - and smelly. The dipstick showed no oil, although I know there is sufficient oil in the crankcase. The engine wouldn't start, so I managed to push it into the garage to drain the oil. WHOOSH!!! Out rushed a very thin gas and oil mixture that nearly overfilled the drain bucket. What had apparently happened during those days sitting at a side angle was the Holley 94 carb continued to drip fuel until it overwhelmed the intake manifold and ran into the oil pan, filling it to overflow. The reason I couldn't see any oil on the dipstick was i was seeing clear gasoline that had settled on top of the oil or quasi-mixed with it. I refilled with fresh oil and changed the filter. The engine fired right up.
Until I can address the carb issues over the winter, I intend to cut the fuel pump a couple seconds before shutting off the engine to eliminate possible lingering pressure in the line that forces gasoline to continue to dip. I will also use the on/off valve under the tank to shut off the fuel flow to the carb. So far, this seems to be working in the garage. I haven't had a chance to test this theory after driving the car to see if dripping fuel is why the car is so hard to start after driving it. That might have been the problem all these years when a hot start was problematic. I have to believe it's all related.
I see that the OP stated he has no fuel pump, so that can be eliminated as possible trouble maker. But I would also suggest turning off the fuel a few seconds before killing the ignition. Maybe we share the same problem?
Marshall
 
Last edited:
OOPS! "40 Deluxe" and I were typing and posting at the same time with similar suggestions. 'Sorry for the duplication of the same information.
Marshall
 
40 Deluxe said:
Try shutting off the gas and running the engine until the carb is dry. Then the next day, turn the gas on, wait a few seconds for the carb to fill, and then try starting it.
Click to expand...

that works, but maybe the fuel shut off valve is worn out. i have a Weber on my car and i had the same problem. i have rust in the tank and it got into the valve and wore it out. also
the valve was hard to shut off. your engine is flooded very bad. you are washing down the cylinders. washing all the oil off the cylinders
 
when i park my A in the garage i shut off the fuel, and let the motor quit. then there is no gas in the carb. but if your fuel shut off is worn out it will not shut off all the way.
 
Thanks as always for the advice. Looks like I have some stuff to try this weekend. I do have a fire extinguisher with me :D

I always shut the gas valve off before I pull into the garage so I don't think it leaks while sitting. I've cleaned the sediment bowl and there was no gas flow then so I think the shutoff works. Maybe I should remove the sediment bowl and put a can under it to see if the fuel shutoff leaks slowly.

I don't think gas is getting in the oil. The level doesn't appear to rise. Maybe I should drain it and see if gas settles to the top of the old oil.

I'll try running the carb dry then starting it the next day. If no spray then that should prove gas is somehow leaking into the intake/motor.

Thanks for all the suggestions as always. I'll try these experiments out this weekend and try to figure it out.
 
Smell the dipstick, too. If you smell more than a trace of gasoline (after all - the car DOES run on gasoline!) , fuel is getting into the crankcase. Not good. Boy howdy, did the oil I drained from my engine reek of gasoline!! Thank goodness, I couldn't get the engine started! The bearings would have been ruined and there might possibly have been a fire or even an explosion with that much fuel in the crankcase to the point that it was overflowing. YIKES!!! If in doubt, drain the oil and start over. A Model A oil change costs about $30. A new engine rebuild costs thousands. Take your pick. :)
Marshall
 
unless you are experinced with carburetor repair, I would recomend you have it rebuilt. Charlie Schwendler is on the barn and does excellent work on Strombergs.
You can contact him on here as Charlie ny. Email. cas5845@yahoo.com

John
 
Float spin a leak and drop the the bottom on the well and is floating your motor
Take float out and put it in a pot of boiling water to check for leaks

Change oil after fix
 
I originally started 2 threads one for the oil leak and one for the carb but its starting to look like its 2 symptoms of the same problem. Here is a link to the other thread just for thoroughness.
https://www.fordbarn.com/forum/showthread.php?t=247943&showall=1

Last night I cranked the car over without pulling the choke or pressing the accelerator and like usual gas blew out the exhaust manifold to exhaust pipe junction. So I think that means the fuel is already in the motor and I wasn't adding it by pumping the pedal or choking it.

I checked the oil it was right at F like normal. I drained the oil and it was black but thin, so it must be heavily diluted with gas.

I pulled the glass bowl from the sediment bowl, emptied it and reinstalled it. After 24 hours there is maybe a tablespoon of gas in it.

I'm confused, if I've confirmed gas is filling the motor it must be leaking past the fuel shut off and carb. But if the sediment bowl isn't filling with gas how is it getting there?

Is it possible for gas to leak through a sediment bowl without filling the glass?

Can gas leak into the motor from the carburetor bowl when the fuel is shut off?

Is a carburetor rebuild the next step or is there any additional tests I should do?

Any help is appreciated.
 
Steve,
I know you have the downdraft carb setup on there but in all honesty I think I extended great advice to you before which is also below. Go back to the updraft carb, it will idle well when all is right, run well, be easier on gas, and you won't have the other problems you are now.

It might not be on your cool wish list but trust me it will run better and be much simpler.
Larry Shepard

larrys40 said:
I agree with rocket that you are leaking fuel from the carb to manifold. A lot by your description. You have multiple factors from an internal leak inside the carb to needle and seat issues to fuel shutoff Leaking . Your problem isn’t how to start it at this point but rather resolving the above issues before you have a fire.

I know some of you guys think it’s a huge improvement running the Downdrafts but life is so much simpler and runs fine with a stock zenith for a lot less money.
Just my 2 cents worth.....
Larry
Click to expand...
 
It is possible for fuel to get your carburetor without feeling the sediment bowl I had a tractor that would do this all the time. I want to give you this advice Charlie prices has a needle seat for that old carburetor that will hold the fuel I'm in the process of taking the two barrels off of my 49 Ford and replacing both carburetors with those needle and seat

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Thanks for the advice Larry, I didn't add this carb it was there when I got it so I dont have an updraft or an intake that works with it.
 
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