5HP, on Craftsman snowblower , 3 years old.

Late last season it started losing power, idled poorly or not at all. Some popping post fires in muffler especially at low speed.

I got thru the season. Took off carb and sure enough the main jet passage, or what I think was that, was badly clogged. I thought for sure problem solved. Well it ran quite a bit better but still didn't idle well and had that popping at smaller thorttle settings and stupidly figured it just might work itself out. Duh.

So today it snows. Engine will not take a load. Started pretty good when cold but kills under load and starts badly. Pops in exhaust like crazy.

Wasn't sure I had the governer set right so unhooked it and played with it and no matter what I do the thing runs barely. Fuel flow is fine. Looked a carb again, nothing to see. So I wonder, is this really a carb issue?

Any tips welcome.

Bob Pierson

Have you tried a new spark plug??

When the trouble started last year I replaced it but suppose I should look at it again. Will do in the AM.

When they pop like that I always try a new plug first, next I would suspect a blown head gasket, then I would check the valves. Keep us posted and I am sure together we can all come up with a solution.

check the nut that holds the bowl on with the main set screw if there is a 1/4 gap between the thread that is where your idle pickup is you might have a plug idle hole for the idle pickup

Definitely check the very small hole on the side of the "Jet Nut" that holds the float bowl on the carb and be sure the step in the bowl is oriented so the high area is under the float pivot. Have you checked the intake and exhaust valve clearances?

I think the idle air bypass, if that's the term, is clogged. I can't open it up. Something rock hard in there. Ordered a new one for two bucks. Will be back in a week if that doesn't do it.

Thanks

So I got the air bypass and it ran, barely, the same, and then the light went off. There is a molded hose going to nowhere, out of the head, from right under the intake manifold. Sure enough it's a vaccuum hose. Plug it and it runs just fine.

It's a short little hose which as I said doesn't go anywhere. I sure don't recall taking anthing off it but then I am nearing senior age. I can't imagine any function that needs vaccuum on this thing so I'll just plug it and go I suppose. Any other suggestions welcomed.

Bob

That is the crankcase breather tube. There's a disc type reed valve located in the breather assembly, sounds like the reed valve is stuck open not letting engine build any vaccum. Disc needs to cleaned or replaced. If you keep the hose plugged it will start blowing oil out of gaskets and oil fill tube.

What is the model and spec number of your engine?

That would let me know where the hose on your engine is supposed to do.

That hose may go to a primer bulb, if thats the case and it was unplugged from the carburetor then it would keep the engine from running, if it's the oil breather tube I can't imagine that you could find a place to plug it in that would have made the engine run.

It's a breather, which is what I thought initially till I found it pulling such a vacuum. It's attached to a small plate right under the manifold. There is apparantly no reed valve in there and the hose is empty of any valve. There is a subplate which I can't remove easily, I suppose reed could live under there but I don't want to bend the thing, it seems to be pressed into the casting.

I didn't get it running right because the carb was flooding. Now I took it off and found nothing which would explain that. Whatever. I just wonder about this breather. What's missing?

Sears engine # 143. 025001

I doubt that anything is missing from your breather as the IPL shows that breather tube just hangs down from the breather and does not plug into the air filter assembly or carburetor.

You can see an exploded view at this link:

http://www.partstree.com/parts/?lc=tecumseh&mn=143-025001+Craftsman&dn=10EHSSK501167410S-EN

you can also look at the carburetor break down as well here:

http://www.partstree.com/parts/?lc=tecumseh&mn=TEC-640084B&dn=10CA191640084B-CA

That whole breather assembly is meant to be one replaceable piece. Most of these just vent air back into the atmosphere. All a breather does is vent moisture and acidic crankcase gasses out of the engine so it doesn't corrode. Some will have a hose running to the carbueretor. if the hose coming out of that piece is flat, it either just stays there or plugs into the air intake assembly or carb. if you see any nipples sticking out of the carb or breather aseemblies, that is where the hose goes. These engines run like crap if this extra vaccum pressure is off circuit. But I suspect yours is supposed to simply vent out and that's that.
As several people have mentioned, check the brass bolt that holds the bowl of he carb on. These are NOTORIOUS for getting clogged. Its hard to tell too because they have 1 or 2 tiny holes- one on the side in the threads, and sometimes on the bottom. Checl that just to make sure as it is easy to do and usually fixes the problem.

The purpose of the oil breather in addition to venting moisture and acids formed from combustion, is to maintain a vacuum in the crankcase when the engine is running, without a vacuum in the crankcase the engine would use excess amounts of oil.

Been busy as heck and no snow on the horizon so have been putting this off. I'll check the brass bolts ports again, maybe that was it.

I am surprised about this breather, which I thought was a breather and ignored till I put my finger over it and it was continuously sucking, ie. vaccum and it did seem to run better. Started thinking it was on the intake side. Then the carb was leaking so I took that off and that's where I am now. Obviously however it is a breather, I'm not used to looking at flatheads.

How the thing is pulling continuous negative pressure in the crankcase escappes me. I'm probably mistaken but was so sure that is what it felt like.

OK, Put the carb back on. Made sure the ports in the brass nut are clear. They absolutely are.

When cold and choked it starts but won't really rev and kills. When hot it will rev up some but then it slows, backfires thru exhuast and dies. (Whatever that thing was where I thought plugging the breather tube.... well , never mind)

The gas line is certainly not plugged. Several little lakes when taking carb off prove that. The carb is perfectly clean. I don't know about the float height but can't imagine it makes a difference. So it seems like it isn't getting enough gas but why.

To review, this engine has maybe 30 hours on it. It started running crappy last season but it muddled thru. Now it's dead.

I've been keeping my Jap 4 cylinder bikes running for 25 years but I cant make this 19th centruy lump run. Go figure.

I took the carb to a shop. I didn't pick it up and havent talked to them but they replaced the trottle shaft, for fun I guess, and left instructions with the wife to be sure to use clean gas. The gas was clean. whatever.

It still will start when primed, then die.

I don't actually understand the governor and the governor to throttle butterfly link is off but the throttle lever to govenor spring is attached but no matter how I manipulate them manually it is always the same. It starts with a prime, then dies out. About the only thing that has changed is that it not longer pops in the exhaust when doing it.

Bemused in Michigan, but if it snows will go postal.

The throttle link from governor to butterfly needs to be hooked up, as it will hold the throttle butterfly open and allow fuel to enter combustion chamber, if the throttle is not held open the engine will start and die as you describe, or it may sputter for a few seconds and die, unless you manually hold the throttle open. If you do hold it open and the engine starts, you have to be careful not to allow the engine to over speed.

http://www.hobbytalk.com/bbs1/attachment.php?attachmentid=36000&stc=1
Gov.pdf