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-   -   Snow thrower engine problem (http://www.diychatroom.com/f46/snow-thrower-engine-problem-119130/)

KE2KB 10-03-2011 02:35 PM

Snow thrower engine problem
 
Hi;
I have an old Sears Craftsman snow thrower. It was in the repair shop several times last season for auger issues, and when that was apparently fixed, the engine stalled out when under load.

Now, getting close to snow season again, I want to get this thing working reliably, so I am checking out the engine.

The engine starts, and runs pretty well (with occasional sputtering) when the choke is in the closed (start) position, but when I move the control fully to the run position, the engine stalls out, even when not under load.
If I put the choke control somewhere between the start, and run positions, it seems to run better, but sputters and the speed of the engine seems to be varying too much, considering that it is not under load.

From what I understand, the engine is supposed to run best when the choke control is fully open (run position).
I am considering replacing the spark plug, but not sure this will help.
Could the problem I am describing be caused by a bad spark plug?
I removed it, and it doesn't appear to be in bad shape. There is some carbon around the outer ring, and on the center pin, but it doesn't look pitted or melted.

Could this problem be caused by water in the gas? Maybe just a gas dryer would do the trick... I think I used the gas preservant, so the gasoline isn't gelled up or anything.

Thanks for your help

FW

DexterII 10-03-2011 03:39 PM

Yes, the choke allows for a richer mix to get the engine started, and, once the engine has warmed up, the engine should run best with the choke open. Since the gas sounds suspect, I would start by removing any doubts there; drain the tank and carburetor bowl, blow out the lines if possible, and dispose of the old gas. Also remove and clean or replace the air filter. While the carburetor bowl is off, make sure that the float and needle move freely. Spray carburetor cleaner inside the carburetor to loosen as much crud as possible. Fill it with clean, new gas, install a new spark plug, and see what you have. If it still does not run properly, I would then try some Sea Foam in the fuel, and run it that way for at least 20 minutes or so, to see if it cleans out the carburetor. If that doesn't work, you may need to remove the carburetor, and clean it in more detail. It sounds to me as if it is a fuel problem, but, just to be sure, you may also want to remove the flywheel cover, inspect the magneto for rust, and lightly sand it with emery cloth, if necessary. I would also pick up some oil for it, so that once you do get it running, and warmed up a bit, you can drain the old oil and replace it.

KE2KB 10-04-2011 09:59 PM

Thanks very much!
That was very informative/helpful.
I hadn't even thought of the air filter, but of course there has to be one!
I think that I'll do one step at a time, so that if I don't really need to drain the tank I don't go to all the trouble of finding a place that will take the old gas.
I guess I would take it to a gas station to dispose of it. But I would also need something to put it in that I don't want back, unless they will just dump the gas, and hand me back the container; in that case I can just put it into an empty gas can.

This machine actually belongs to my brother. I know the gas isn't more than a year old, since Sears drained the tank when they "repaired" it in February 2011.

I suppose I could also "drain" the gas tank by allowing it to run dry. It's pretty nearly full right now, so that is going to take a few hours.

FW

polarzak 10-05-2011 05:57 AM

Quote:

Originally Posted by KE2KB (Post 742435)
Thanks very much!


I suppose I could also "drain" the gas tank by allowing it to run dry. It's pretty nearly full right now, so that is going to take a few hours.

FW

You could siphon it out or you probably could disconnect the fuel line at the carb and let most of the tank drain into a container. Then start it and run it dry.

daveb1 10-05-2011 07:38 AM

I'm inclined to agree with Dexter's plan. The old fuel can be safely used in your car if there are no visible chunks or dirt in it. That much fuel in a car fuel tank should be no problem. One year old fuel in a small engine (even with stablizer) is probably your problem.

Marty1Mc 10-05-2011 10:42 AM

Quote:

Originally Posted by daveb1 (Post 742556)
I'm inclined to agree with Dexter's plan. The old fuel can be safely used in your car if there are no visible chunks or dirt in it. That much fuel in a car fuel tank should be no problem. One year old fuel in a small engine (even with stablizer) is probably your problem.

Why take the risk for a few dollars? If the vehicle has a carb and it's added to a pretty full tank, yes.

KE2KB 10-05-2011 07:17 PM

I am just concerned about how to dispose of the "bad" gasoline. Will my local gas station dispose of it for me (properly)?
Otherwise, I would have to let the snow thrower run until the tank is dry. I don't really want to put the gas in my car, considering that it's old. All I need is trouble with my car (which does not have a carburetor).

That said, I have kept gas (with stabilizer) in the plastic gas can before, and it never caused a problem. I haven't drained the snow thrower's tank in previous years either.

FW

Marty1Mc 10-05-2011 08:28 PM

I don't know about where you are, but they don't do that here. I usually use it for my branch burn pile (that's legal here) or just leave it in a pan in the sun, it will go away all on it's own.

polarzak 10-06-2011 05:37 AM

Quote:

Originally Posted by KE2KB (Post 742952)
I am just concerned about how to dispose of the "bad" gasoline.
FW

I use it to kill weeds between the patio stones and around the pool deck. Ohhh, bad boy, some might say, but what is the pollution difference using it that way, or burning in off in a snowblower (airborne hydrocarbons) or letting it evaporate in the sun. (more air pollution)

Jackofall1 10-06-2011 06:10 AM

You can start by doing what has been suggested but it sure sounds to me like your idle and run jets in the carb are fouled up. These jets are smaller than pin holes and the tarnish left by gasoline sitting there during the off season will build up and cause exactly the symptoms you are experiencing.

If you are not confident in dismantling the carb, take it off the snowblower and bring it to a small engine shop, they will clean it out and replace the float assembly for about $15 bucks, the gasket kit will come with a new manifold gasket to use when you are putting the carb back on the engine.

Personally I would not use Seafoam on the engine especially as you can't keep it running now, Seafoam will make that worse while you are running it or try to run it with that product in it.

Mark

DexterII 10-06-2011 08:12 AM

Yeah, not to confuse the issue, but I can't really disagree with Mark on the Sea Foam; might not be the best choice at this point. I have had what I attibute to success with Sea Foam, and I use it fairly regularly in my rototiller, snowblower, and generator, but he's right; it's not a cure-all, definitely not a replacement for a thorough carb cleaning, and could in fact get you to a point where you can't run the engine at all. If you do end up removing the carburetor, if need be just tap on it lightly, with a rubber mallet, to loosen it, and pull it off; don't pry it with a screwdriver between it and the block, as you could damage your mating surfaces, and mark your cables when you disconnect them, so that you put them back exactly where they are now. Not that they may not need to be adjusted at some point, but at least you'll get everything back to a point where it will run.

KE2KB 10-06-2011 09:07 AM

Do you think that any of the gasoline additives that are supposed to help clean the carb are worth a try?
I'm figuring to get away with as little work as possible.

I'm not particularly mechanical, but I have cleaned my old car's carb before. That was when I was young, and enthusiastic about such things. Now, I'm a lot older, and getting tired of these little jobs.
Maybe I'll take Jackofall1's suggestion and remove the carb take it to a shop.
Still, how complicated could it be?
I'll at least take the cover off and have a look. What usually happens in these situations is that I'll have a look at it, decide that it's not so complicated, then end up doing the work myself. For me, it's the anticipation of doing the work, not the job itself that keeps me from getting to it.

I am not allowed to burn anything outdoors here in NJ. I don't think pouring the gas on the ground would work either. It may create enough of a stink that someone will call the fire department, and I will be issued a summons.

FW

DexterII 10-06-2011 09:23 AM

Quote:

Originally Posted by KE2KB (Post 743229)
Do you think that any of the gasoline additives that are supposed to help clean the carb are worth a try?

Definitely not. The only "additive" that I would use in something like that is Sea Foam, even though it does not fall into an "additive" category, at least in my opinion. But, as Mark (Jackofall) alluded, which I agree with, and which prompted me to back off on the Sea Foam suggestion, the engine is not running right now, and there is nothing that you can dump in the fuel tank that will magically change that. If you do add anything, the chances are extremely high that you will go from and engine that is not running right on gasoline, to an engine that is not running right on what essentially aamounts to a home brew. Personally, I would prefer the engine that is not running right on plain old gasoline, because that I can do something with.

Marty1Mc 10-06-2011 10:07 AM

If you are going to take the carb to someone, take the entire unit. That way, they can fix the carb and adjust it, get the unit running correctly. Like, DexterIII, I prefer the entire unit.

KE2KB 10-07-2011 05:09 PM

Well, despite the warnings, I did buy a couple of Prestone gas additives. One is supposed to clean fuel injectors (and carbs I guess), and the other is supposed to remove water. The latter is just alcohol, but drygas has worked for me in the past.
These products were very cheap, and with a special offer, I get one of them free anyway.

Let me clarify something first: The engine is running. It is just somewhat balky. Before I did anything, the engine would start when the choke was in the full choked position, but would stall out when I opened it to the run position.
I managed to get it to run in the open position by adjusting one of the screws. It's the one on the side with a spring around it. There are two such screws next to each other, but the other one adjusts how far the automatic choke will move during operation. That is connected to a rod that goes into the engine.
There is another screw, also with a spring under the bowl, which I suspect adjusts the float itself, but I didn't touch that one.

After making an adjustment on the one screw (I turned it clockwise to it was being threaded into the carb, then the engine would run when the choke is in the open/run position.
At some point it seemed to be running pretty well. I was able to engage the auger and the drive without having the engine stall out.

But after I shut it down, then re-started it didn't run as well anymore, even though I didn't touch anything further.
I suspect what you guys are telling me; the carb is gunked up, and that is causing a couple of things;
The nozzles are partially plugged, and the float is sticking. I think that if I rap on the housing it will fix the situation, but I haven't tried that yet.

The gas additives did absolutely nothing, and even replacing the spark plug didn't seem to change anything. But again, the plug was very inexpensive, so it's a good measure regardless, in a machine that old.
i also changed the oil, but maybe I should have waited to do that, as it may get dirty again if the engine isn't running well. I will check that once I have it running right, and change it out again if necessary.

I am thinking now that I will need to buy the carburetor rebuild kit from Sears, and see what I can do. It doesn't look too scary; I think I could handle it.
One thing I need to learn though, is which screw to turn when in adjusting the carb. I am just fiddling with the screws, getting an idea of what is happening, but I know that there is a proper procedure. I'm sure I can find this online.

If I cannot get it running well, then I will re-assemble the carb and take the whole machine to a shop, other than Sears.

Thanks for your help.

FW


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