I've done a ton of car work over the years, but actually very little engine work. A testament to how good modern engines are, I guess... So my snow blower engine is acting up. It had been reliable until after the first snowfall this year. It's about 12-13 yrs old, but only gets used for 2-5 hrs a year. 5 hp Tecumseh on an MTD 21" 2-stage blower.

It used to start by going to full choke, prime a few pumps, and then pull. Would start within 2-3 pulls. Then dial the choke down to full open over the next minute or two and all was good.

Now, it won't start on full choke, but will only on partial choke, but I have to pull it several times and it clearly is not happy. I also noted that it does not seem to have the same power it used to when blowing snow.

Basics: Gas is good, fresh. Intake and exhaust were looked into and there is no plugging-up going on there (winter engine - no intake filter and nothing in the flow path that could be an issue). Every year I drain the tank and run it till it dies before storing for the summer. Changed the oil every couple years. It has "good" spark, best I can tell, but I have not yet changed the spark plug. Plug does not look bad - generally lighter-med brown color. No sludge/carbon or damage on it, and gap is close to spec. I am aiming to change the plug "just because."

I did check compression but did it with the engine stone cold. I got 50-60 psi over a few tests. That sounds very low to me, but then I think you are supposed to check it at operating temp so the rings are seated properly. I aim to do that, maybe tomorrow.

I guess from what I read I am either looking at carb issues, or maybe the engine needs new rings and honing for compression (obviously never done that, myself).

This engine has 2 output shafts. 1 is the main crank, 1 looks like an extension of the cam shaft. 1 drives the wheels, 1 the auger/blower. I don't think this is a super-common engine to find a replacement for (and Tecumseh went bankrupt), plus I need some engine work experience so I am looking for the low down from the experienced folks. What to look for and probable causes. If I need to tear into the engine, I actually found the shop manual online, so it should be a fun little project.

Any help would be appreciated. Fortunately we don't get a ton of snow here...

Thanks,
Dave

 

There is no valid reason for this problem to be anything other than fuel related unless you used it to blow leaves in the fall and ingested dirty air.

When you drain the fuel out, do you remove the bowl of the carburetor? If not, you are not getting every drop out and the residual fuel can leave a varnish/gum substance that will clog your main jet.

Another common problem is the rotting of the rubber primer hose.

Were it mine, I would:
Turn off the fuel from the tank.
Remove the shielding from the carburetor area.
Remove the needle and seat assembly from the underside of the carb bowl as a unit.
Slowly turn the needle clockwise, counting the number of revolutions and partial revolutions as you do so to establish its original position. Then, unscrew the needle completely.
Gently clean the needle and jet with a solvent like denatured alcohol, being sure to run a very fine wire through all the openings and use the air gun to blow through all the little openings.
Carefully remove the bowl and clean the inside of the bowl. It is not recommended to use steel wool to clean the bowl as that will remove the clear finish that helps prevent corrosion. Mild solvent and stiff rag will suffice.
Hold a container underneath the carburetor and turn on the fuel at the tank. Be sure you are getting a steady trickle of fuel. Be careful jostling the float around or the float needle valve will come out and it is a bit of a bugger to get back in without detaching the float itself. Try to avoid that as many Tecumseh carburetors have a little spring that applies a slight upward pressure on the float and it is truly a PITA to get back together.
Reinstall the bowl and the jet (without the needle) and turn the fuel back on. Again, you should have a steady stream of fuel coming out the bottom of the bowl.
Reinstall the needle until it seats and turn it CCW the same number of turns as it was when you first removed it. (if it is a Tecumseh carburetor it should be 1 and 1/2 turns from the seat).
Replace the spark plug "just because" it is very cheap assurance that removes one possible culprit from the equation at a very reasonable price. Champion RJ19LM is a suitable plug if you can't find whatever brand MTD put in originally.

That should take care of any fuel issues in the high speed fuel circuit. If you have a blockage in the idle circuit, that is a different matter and will require removal of the carburetor to fully clean.
Most people do not realize that an engine of this nature gets most of its fuel through the idle circuit when the engine is not under load. It may work fine if you can get the auger to engage without it stalling out.
If you can get the thing to start and stay running with the auger engaged or disengaged, run some carb cleaner (SeaFoam) through a full tank of fresh fuel.

I generally suggest folks fill the tank with stabilized fuel at the end of the season to prevent gum and varnish deposits as well as condensation collecting in the fuel system. If water condenses in an empty tank, it may very well run right down the fuel line and into the carb bowl. If condensation collects at a low spot in the fuel line, it will not evaporate out anytime soon as there is too little surface area.

Your repair manual will have all the carburetor parts I mentioned identified. Tecumseh makes an OK manual, but they do assume the person using it has some background knowledge.

Most small engine OEMS do not publish compression PSI ratings, but 60 doesn't sound bad for a 6:1 compression ratio engine. And yes, it makes a big difference if the rings are hot and expanded to seal to their full capability.

And I seriously doubt you have even diminished the crosshatch in the cylinder or worn the rings appreciably with the number of hours on the engine, assuming it has only been run in the winter to blow snow. There are really no abrasive contaminants in the air in the winter when blowing snow and that is really the only way to cause excessive ring/cylinder wear; hence no air filter on snow blower (or most boat) engines.

Post here again or PM me if you have any questions or run into a problem.
Here is a write up I did a few weeks back that has much of the same info:
https://www.ford-trucks.com/forums/1...e-of-year.html
For sure let us know how it goes.

 

Thanks, Kal. I was hoping you would see this and respond. I'll look into what you posted and follow up. I hate working in the cold garage and it is going to be a very cold week, from the looks of it. I do have an electric heater in there, but it mainly takes the chill off, especially with outside temps in single digits.

And yes - it has only used for snow in the winter and total hours on it are maybe 50-60, I'd guess.

I don't like storing equipment with gas in it, so I drain and run it out, but I know it is not perfect. I should drain the bowl too. Perhaps I will need to start doing that. The gas tank was bone dry when I opened it up to fill for the first time, so I doubt there was any condensation.

 

as Kal said, that engine is still brand new, and only needs carb work.
with the new ethanol additives in the gas the past 7-8 years, all kinds of things are happening to the carbs on engines that were not designed to use ethanol gas.
one of the biggest being that ethanol messes up the gaskets in the carb.

i have basically the same blower, a MTD 5-22 of the same vintage, and had to rebuild the carb 2 years ago. the only thing i have not done to it is replace the primer pump that the ethanol destroyed.

 

Without a doubt, today's gas is not at all carburetor friendly. You have to balance between the damage leaving the gas in and everything gumming up to draining everything and the gaskets and rubber parts drying out. The best prevention is to start it every month or so, but who remembers to do that?

I try to run my small engines out of gas and then drain what's in the tank and put it in something I'm using so I don't waste it, and then put fresh gas in every so often and run it a bit, but even doing that I'm still pulling the carbs apart every so often and cleaning them out.

Not much sense in buying a new motor either, if you treat it to the same usage cycles you'll be right back into the same problem sooner or later. It's really a matter of getting familiar with taking the carb apart and learning how to clean it out. You can do it; just take your time and be careful where you do it so any of the small parts don't fall on the floor and disappear.

 

One note though is that Tec. engines aren't made any more and in some cases makes getting parts rather difficult. Also generally they don't rec running a metal wire through any holes. I usually either use a toothpick where I can or WD40 with a noozle to open things up. I'm in the same position though in that I have a 5hp Tec that decided it didn't want to run. I do however just buy a electric snowblower and got to use it today. Nice to just plug it in and go clear the driveway. I'll get around to the carb. Sometime.

 

Take the spark plug out and clean the electrode/element with a wire brush.

My story- Purchased a Ariens 2 stage 24" snow thrower with the Subaru engine last year....In the middle of snowapalooza. Used it for a few hours. This year I went to start it and it ran for a few seconds, sputtered and died.

Stale gas. Luckily it was almost empty. I put in fresh gas & still would not start. Cleaned the spark plug and it fired up in 1 pull.

Like Ckal704 said, its fuel related.

I'm no expert, I'm a big dummy when it come to this, first home, first snow thrower and recently, first riding mower (sale @ home depot, nows the time to look for bargains )

 

I agree that OEMs do not recommend running wire through fuel orifices, but to be honest, all I have ever used is an oxy/acetylene torch tip cleaner. I think if one is prudent regarding the amount of force used with the wire you can get away with it.
Besides, Tecumseh carburetors have a tiny tiny hole in the side of the jet that is the air bleed. Sometimes they are hard to even find if only a little crud gets on the jet. In a non-adjustable carburetor (as more and more are these days) the tiny amount of air that enters the fuel streaming up the main jet into the barrel of the carb is fairly critical to the overall mixture. The only thing I have ever found that was small enough to fit in that air bleed hole is the smallest tip cleaner in the set.
Most tip cleaners have a small section at the far end of the cleaner that has no serrations or ridges on it. That is the part that I use. I think the main precaution is to not use the serrated portion as an overzealous cleaning effort would, in fact, result in enlarging the jet.
This probably would not drastically affect engine performance-might even improve it in some cases-but OEM's have to go on record recommending practices that will not affect the engine's meeting EPA emissions standards to cover their butts. Perfectly understandable.
I've worked on hundreds of snow blowers over the years. >90% of problems are fuel related. Every once in a while you get one that has never had the oil changed and, even though the hours are relatively low, the oil has lost its lubricity, causing bearing damage.
Older engines with breaker points are subject to corrosion on the points requiring cleaning and re-gapping or replacement. But nearly everything built after around 1980 has electronic ignition, and they rarely (but sometimes!) go bad.

Expecting 2-4 here tonight into tomorrow. I only have a little 2-stroke Toro sno-throw machine. My driveway is situated that I do not have a place to blow snow with a larger machine. My barn borders one side of the drive and my neighbors drive borders the other side of the driveway. It is easier for me to plow the snow and push it across the street and over the bank.

Good luck!

 

When I get around to going through my carb I might have to break down and use a wire, but so far I've always been able to get by without it. However in the last year or two it seems like carb troubles have gotten worse. I'd kind of like to get it running though since I have a son in law and daughter they bought a house and could use one.

 

Well I got to it this afternoon. There was no main jet screw in the bowl - just a brass nut holding the bowl on with some passages drilled into its shaft area for supplying fuel up the main jet. There was also a bowl drain, so I will use that in the future to get all the fuel out (hadn't looked way up under there before). I cleaned it out, but it all looked pretty clean to me. Used some alcohol and compressed air in the passages in the nut and wiped out the bowl. It seemed to start better after that and run a bit better, so maybe there was something in there, but it wasn't obvious. I'll wait and see how it performs during the next snow and report back.

Thanks for the help!

 

Ont the bowl nut, at the top where the threads start, if you look real closely, theirs another hole drilled into the side. Make sure that hole is clean also. A wire from a bread bag will fit in it. Its real small. Also their is a hole at the tip of the mixture screw, that is under a rubber cover, on the side of the carb. Screw it out also and clean the hole in the tip of it.

 

Yeah I saw all the holes in the nut, so I got all them, including that tiny one. It all looked pretty clean, so maybe there was a small particle that was gumming up the works. Dunno. I'll see how the next snow goes, and then go back in and hit the mixture screw you noted if I have more trouble. Thanks!

 

dstig1, lots of great info here I was having a problem with my older snowblower and used youtube videos to help resolve the problem with the carb and idling problem.

http://www.youtube.com/watch?v=1f0Ld...eature=related
http://www.youtube.com/results?searc...nowblower&aq=f

 

This gas they are selling is junk...this past fall as I was running a leaf/yard vaccum, it ran fin until I put some new gas in it. Stopped running halfway thru. Couldnt figure it out until I tore carb apart and found dirt in it. Now I had just cleaned everything out during the summer and put all new seals and gaskets in it. Look in my gas can and see all kinds of crap in there that was not there before. I also saw at my one local rental yard that they sell stuff that neutralizes the ethanol. I havent tried that, but after fixing a few other engines with rubber rot due to ethanol, I might try it. What I started doing is putting fuel shut off valves and filters on gas lines to.

 

Well got around to looking at the snowblower this weekend. Got it running again but it still isn't right. Still hunts a some until under load and when you try to prime it, it will start overflowing gas until you disconnect the line to the primer and then it seems to be OK. Got too cold out so I quit for now on it, but at least it can work if we get another snow.