carb sticking

Ken Timmerman

Ken Timmerman

Junior Member
Carb was operating fine. Today the carb throttle arm/shaft/plate is stock solid. If oil or PB Blaster is applied to shaft, it frees up and work OK. The next day it is stuck solid again. And I did not apply anything to carb.
 
Probably the corn syrup turning hard from the heat. Usually it happens to the valves when the engine sets over winter. I always mix 4 ounces of Marvel Mystery Oil with each 10 gallons of gas, and I almost always use only the good gas without corn crap in it.

Spray some Kroil on the shaft and see if that won't free it up.
 
Put some Marvels Mystery Oil on the shaft and work it a bit, then put some more on for good measure. I bet it frees up fine.
 
Are you sure it isn't the cross shaft linkage mounted to the top two flywheel cover bolts?
There are 2 hidden oil pockets on it, and they are often overlooked. You could unclip the linkage at the carb and try the shaft to see which part is sticking.
 
If it really is the throttle plate on the carb that is getting stuck, you need to note only lube it but also clean it. Once it moves use carb cleaner to get rid of the deposits that are sticking.
 
Thanks for ideas.
Update-I have been getting this A running for road for 90 year old friend. The vehicle had set in his garage for 12+ years. I have gone thru $1300 in replacement parts. Put in five gallons of gas when restore was started 6 weeks ago. Last Saturday I took it out for its final road test. It ran out of gas. So, I added another five gal. Then is when the problem started.
I have removed the carb and found the throttle plate completely stuck. The plate has a thick black film and will not move. So, now the problem is identified but am not sure of the cause. Although it could have something to do with running out of gas. Maybe the goo was sucked out of the empty tank? I hope after the black goo is removed the plate will move again. Am not sure what chemical should be used. Then what about the gas tank?
I did not know this was going to be such a convoluted restart. There was many part needed replacement and of course all the parts needed were discovered as I went along. I'm sure Snyder's and UPS got rich over this one!
 
you might have crap / goop/ oozing out the intake manifold onto the throttle plate after shutdown
old gas can cause that

your lucky the valves are not hanging
 
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I would flush fresh gas throught the tank several times and run it through a cloth to catch the junk. Then install the small brass filter in the top of the shut off valve.
 
If the issue was that goo from the gas tank caused your issue then the entire carb would be full and a mess. I would say it old left over crap that is coming loose in the throat of the carb or in the intake manifold. If it is a zenith carb it could just be rust in the throne of the carb. I see a lot of old carbs with stuck throttle plates, most can be freed up by using a little heat and some of whatever you like for thin lube, WD PB,etc. I do agree you also need to flush the gas tank as any crud will find its way into the carb and cause other problems.
 
jmeckel said:
If the issue was that goo from the gas tank caused your issue then the entire carb would be full and a mess. I would say it old left over crap that is coming loose in the throat of the carb or in the intake manifold. If it is a zenith carb it could just be rust in the throne of the carb. I see a lot of old carbs with stuck throttle plates, most can be freed up by using a little heat and some of whatever you like for thin lube, WD PB,etc. I do agree you also need to flush the gas tank as any crud will find its way into the carb and cause other problems.
Click to expand...

yep
 
Above comments are correct in that ethanol gas will dissolve coatings in any old vintage vehicle gas tank, for any type of vehicle, (i.e. tractor, car, truck, etc.), that was never before affected by non-ethanol gas.

Just one (1) Model A experience with the later introduction of ethanol gas:

My Model A tank was coated years ago, maybe 30 years ago, with what appeared to be the former Model A recommended "Permatex/Alcohol" tank sealer, which afterwards sat without running for about 23+ years.

After being later introduced to the new ethanol gas, the carburetor & intake quickly developed a very thick coating of black goo in just one (1) later 20 mile outing.

This thick coating resisted being removed & cleaned with lacquer thinner, paint thinner, alcohol, gasoline, kerosene, PB Blaster, Marvel Mystery Oil, Liquid wrench, Kroil, transmission fluid, & several other name brand penetrating oil.

FWIW: This thick coating was easily totally dissolved & very easily & quickly removed from all carburetor internal parts & intake manifold with a 1:3 mix of "warm" water based POR Marine Clean to (3) parts hot tap water.

Later dissolved & cleaned the majority of the inside tank lining with warm Marine Clean by circulation same though the tank with a small circulating pump.

My 1947 cub tractor had this similar problem after introducing ethanol gas; however, this ethanol gas dissolved what appeared to be old gas varnish like residue.

Hope this helps someone, some day, with the adverse effects of ethanol gas.
 
Tom Wesenberg said:
I would flush fresh gas throught the tank several times and run it through a cloth to catch the junk. Then install the small brass filter in the top of the shut off valve.
Click to expand...

A great idea. Get that old residue out of the tank and replace all the filters. Until you do you will have numerous problems. Wayne
 
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