Tecumseh Snowking LH318SA snowblower engine no start

[earl84]

Stored last year and ran carb dry first. Gas was no ethanol with Stabil added. Cleaned carb anyway, no go. Got a new cheap Chinese carb, still no go. Almost wants to start, but no go. Thankfully, it has electric starter.
Strong spark, really strong
Gas is getting to cylinder, spark plug is wet
Compression around 110
Took cover off and it appears valves are moving fine Sprayed starting fluid while cranking and it did not start then, either.
Checked for wasp nests in intake, all clear.

I‘m thinking sheared crank key, maybe, throwing off timing? Anything else to check without taking the whole thing apart or punting it to local small engine guy? I’m pretty handy, but more of a parts replacer than mechanic.

 

[Improved700]

Pretty simple engine as you know. Seems that you have checked the boxes for the big three. Spark, fuel, compression.
If intake is clear, any change you could check the exhaust. Maybe pull muffler? Perhaps something is in there?

I could get behind the sheared crank key, but I would think it would take something major to make that happen. Like a lock
up while running, something of that nature.

Very odd that you have spark and compression, but when you spray starting fluid, it does not offer, or even try and fire.

Wish I had more to offer. Curious as to the outcome

 

[Zeke]

You should be able to check roughly when the spark occurs. Pull the plug and ground it. Put something in the hole that gives you indication of TDC. Just quickly turning the flywheel at or just before TDC, you should see the spark. If way off then you have one answer.

I'm going with the unlikelihood of a sheared FW key. Exhaust blockage would be my first check. You could find the exhaust stroke and blow air in the SP hole and listen to keep it simple before turning nuts and bolts.

Wet plug, spark, no start; it has to be something simple.

 

[earl84]

Just throwing it out there in response to clogged exhaust, there is smoke coming out of the muffler. I could certainly take it off more easily than the flywheel, so I’ll do that next. I’ll try out Zeke’s suggestions also. Thanks everyone.

 

[LopezBart]

To check the spark, you pulled the plug and laid it on the cylinder head and watched for a spark, correct? Otherwise plug may be shorted. It ran when you put it away, so very unlikely that there are mechanical failures like keys, valves, etc. I'd replace the plug just in case.

 

[earl84]

Correct, Lopezbart, that’s what I did.

 

[Bill Bowman]

taryl dactyl to the rescue. You Tube guru GOAT.

 

[finn]

Pull the muffler and try again.

Likely something is living in there

 

[nadogail]

Replace the Tecumseh engine with a Honda.

To the best of my knowledge, Honda Industrial Engines are the “Gold Standard”.

 

[Motown]

Is the flywheel rusty? That can cause a week spark. As others have said ck they flywheel key. Sometimes you can see if its sheared by just removing the nut holding it on. If you need to remove it loosen the nut and pry lightly from behind and tap the nut on the end of the crankshaft, they will usually pop off.

 

[Mr.N]

Stored last year and ran carb dry first. Gas was no ethanol with Stabil added. Cleaned carb anyway, no go. Got a new cheap Chinese carb, still no go. Almost wants to start, but no go. Thankfully, it has electric starter.

How much you want for the Tecumseh carb?

 

[earl84]

More troubleshooting today.
Valves are moving fine.
Gas is getting to spark plug, spark is phenomenal.
Pulled muffler, no blockages.
It fired for about 2 seconds. oddly enough it sounds like it’s starving for gas. BUT, it doesn’t do anything with straight starting fluid.
Pulled flywheel, the key way and flywheel were not out of synch. While I had it off, emery cloth to all the magnets, coil pickups, etc. BUT, spark is not an issue.
Double/triple/quintillion checked it wasn’t grounded out by key or throttle shutoff.
Fiddled with governor to throttle arm while cranking, along with choke, in just about every imaginable combination I could physically perform, and nothing made a difference.
I’m ready to take it to small engine guy, unless someone has a great idea.

BTW, I got this for free 3 years ago, and the stock carb was basically a ball of shellac, so I got a cheap Chinese carb, and it ran great for 2 winters. Maybe I should throw an OEM carb at it, but it has zero desire to run even crappy.

 

[Zeke]

Spark plug maybe getting wet due to choke. I'm sure you're using the choke on a cold engine. The idle jet may be fine and the main jet is clogged. Is this an adjustable carb or more or less fixed jets? If you can pull out a jet needle and squirt some carb cleaner in there you might get this thing going.

If not all that accessable, remove the carb and do your best to blow it out with some cleaner and air if you have any. I like to do this outside over a white cloth or paper towel to see any detritus that falls out with the cleaner. IDK the carb, but taking bowl off might tell the story even if put away well. You may need some Hylomar on the gasket when reassembling so it doesn't weep.

If this works then you may have to change your routine when storing engines.

I've worked on lots of small motors and when they piss me off I buy new carbs. I've had Dalmation hairs get all the way down to the jet. Hard to find and see. Somehow they either get past the filter or just stick to a funnel, etc. and I don't notice them.

 

[HalfTonTom]

Maybe you're just not using the correct curse word combinations.

 

[earl84]

Appreciate checking back in, Zeke. You may be right about wet due to choke. The thing that I have a real struggle with is why it literally does NOTHING with starter fluid and strong spark.

 

[BillK]

Throw the starting fluid away before you ruin the engine. Use Gumout carburetor cleaner instead. Mine always starts right up with a shot of that.

 

[oldmxracer]

I am not a fan of China carbs but if it worked for 2 years. Have You tried a NEW out of the box spark plug ? Sounds to Me like You might need one or at least give it a try.

 

[Zeke]

Also wet plugs tend to not operate. I don't know why that is, but whenever I've flooded an engine, it won't start until it's dried out including cleaning or replacing the plug. I raced Yamaha powered karts for 40 years. Well, there were some McCullough's early on. When they didn't start it was an automatic reaction to pull the plug and put in a new one.

So I'm a 2-stroke guy and they can be fickle. Especially kick start bikes. I've had lots of small 4-cycle motors too. Carb issues are No 1.

 

[larry4406]

Years ago I had a mini-bike with a Briggs and Stratton engine that had a Champion plug. Damn thing would spark beautifully when tested by grounding to head cooling fin, but would not fire under compression. Tossed it, put a new one in, and away I went.

Drove me nuts.

 

[Zeke]

That's what I'm talking about.

 

[earl84]

Guess it’s time to swap out the plug, which seems weird, but nothing else seems to be wrong with the dang thing, and it should run, or at least fire reliably. Otherwise, I give up and the small engine shop will get some work from me.

Thanks everyone, I’ll try to report back in the next few days.

 

[mreisner]

Most Small Engine spark plugs are junk compared to what they were years ago. Buy two new spark plugs as I have seen new ones be bad right out of the box. It may have a strong blue Spark with no compression, but when screwed in the head and under compression it may be very weak.

 

[LopezBart]

Most Small Engine spark plugs are junk compared to what they were years ago. Buy two new spark plugs as I have seen new ones be bad right out of the box. It may have a strong blue Spark with no compression, but when screwed in the head and under compression it may be very weak.

When the plug is in the engine - even a 6:1 compression ratio lawnmower, it's much harder for the spark to jump the gap - a bit over 2x the voltage is required according to https://www.mazdamaniac.com/spark_gap_calculator.htm . If the insulation is marginal in the plug, it may handle the 5700 or so volts to jump the gap in air, but since in the engine it might take 10-12k volts to do the same, an internal short may bleed off the current and prevent the spark.

 

[oldmxracer]

This is why I did My first post #17 just fixed a small motor for a friend that was driving Him nuts new plug and it ran great !

 

[Farmall450]

Also wet plugs tend to not operate. I don't know why that is, but whenever I've flooded an engine, it won't start until it's dried out including cleaning or replacing the plug. I raced Yamaha powered karts for 40 years. Well, there were some McCullough's early on. When they didn't start it was an automatic reaction to pull the plug and put in a new one.

So I'm a 2-stroke guy and they can be fickle. Especially kick start bikes. I've had lots of small 4-cycle motors too. Carb issues are No 1.

I feel my snowmobile is the opposite; it'll only start if they're wet. Ether won't kick, but filling the jugs with 50:1 and giving it a few pulls will.

 

[jonesg]

I feel my snowmobile is the opposite; it'll only start if they're wet. Ether won't kick, but filling the jugs with 50:1 and giving it a few pulls will.

same here with my skidoo, 2 strokes like to fire juicy when cold.

But this snowblower is a 4 banger , i had the same problem, 5 ys ago I went to HF and bought a predator 9 hp, the mounting holes and output shaft dia are the same. its a honda clone. It still runs perfect.

 

[trainer]

The first thing I'd do is drain the tank and start with fresh gas.

 

[jonesg]

the middle of winter with storms coming one after each other is no time to be trying to get balky engines going.

 

[Zeke]

the middle of winter with storms coming one after each other is no time to be trying to get balky engines going.

He has a choice? As in shelling out for a new blower when a carb will do?

 

[gizardlizard]

He has a choice? As in shelling out for a new blower when a carb will do?

I think his point was to do the pm on the snowblower in fall before the season starts and not wait until you need it to see if there are issues.

 

[Zeke]

Well, I think he got caught short and thought he had put the thing away so it would live another season. Something went awry and it can't be that complicated. I'm just in favor of getting the thing going if it was a good machine 12 months ago. Falling behind on the snow is the only problem so maybe for the next few days it takes to get a carb, he can hire it done, borrow a blower, etc.

OTOH, he could buy new (not the best time for a deal) and in the meantime get the old one running and sell to recoup costs. Or, If there is room, keep it as a backup maybe renting it out now and then.

So yeah, he does have options. I just had to think about it.

 

[jonesg]

He has a choice? As in shelling out for a new blower when a carb will do?

he has choices but not time.
i got caught like that with a briggs , after putting $60 in parts in it as snow fell i repowered it with a predator.
figured i could mess with the briggs later, never did get it going so I took it to the dump.
now i always run it in the summer and again in the fall before the snow.

 

[Monza Harry]

I'll go with the plug diagnosis. As noted (a lot) above, outside of vs. inside the cylinder spark, are different! While not an absolute [a leaking porcelain will stymie this tester] try one of this type of spark verifier: https://www.harborfreight.com/in-line-spark-checker-63590.html
but for $5 these are a handy tool! Also do a visual check of the plug wire/boot, with an in the dark pull of the rope while watching the wire/boot there should be no light show! Those can both be a cheap easy fix but not always. The boot commonly has a small threaded piece that turns into the wire. Worst case you buy a new coil/wire/boot ***'y. A quick, it's snowwing fix is a healthy spray of silicone spray for a one time band-aid on a gun shot wound fix! Harry

 

[theoldwizard1]

Gas is getting to cylinder, spark plug is wet

Too much fuel can "splash foul" a plug. Replace it. Next time, don't choke it or only choke for a few cranks.

I‘m thinking sheared crank key, maybe, throwing off timing?

Checking valve clearance is easier than checking for sheared key.

My bet is too much fuel.

 

[FlaGman]

My problems have usually involved the low oil pressure switch. It seems like you have good spark, though….

 

[nbpt100]

Old gas or contaminated gas?. You exhausted so many likely issues. Just drain the old gas and put in fresh. I am not sure why you thought the carb was an issue? Did I miss that?

The last 3 of 4 Chinease carbs I bought did not work. They used to be pretty reliable but in the past year the quality has diminished.. I clean Tecumseh carbs and have good success. You can get a rebuild kit on line for $10 to 15. Unless you have an ultrasonic cleaner remove the welch plug over the idle circuit. Wtih a little bit of love they are reliable and work horse engines. If you want to repower get the 8hp Preditor. Honda's are great but look what you pay for one. There are lots of good testimonials out there on people who have used Preditors on snow blowers. I have one that is on 10 years right now. Going strong.

 

[The Cobbler]

try another plug, put a bit of gas in the cylinder, put the plug in and try see what it does . if it has spark , timing & compression,it should fire off and run for a second.
if it doesn't fire, you're missing something other than fuel .
if it does run, you should be able to keep it running by shooting a bit of gas into the carb with the choke open and throttle a bit above idle .
if it runs decent with that , you have a carb/fuel issue . and be sure that the carb and intake aren't leaking air in too, that could cause a no run.

 

[nbpt100]

Most Small Engine spark plugs are junk compared to what they were years ago. Buy two new spark plugs as I have seen new ones be bad right out of the box. It may have a strong blue Spark with no compression, but when screwed in the head and under compression it may be very weak.

Yes. The Champion RJ19LM or J19LM should be good. If it is 30 plus years old it may call for a CJ8 but the others will work fine. With the exception of ngk the other brands the counter guy my try to sell you off of his x ref book will not work as well in this engine. Bosch-autolite-ect.

 

[earl84]

Well, I finally got to town today and bought a new plug. I’ll be darned if it didn’t fire IMMEDIATELY! I frankly would have never believed it had I not seen it myself. I guess everyone who had that experience helped convince to at least try a new one. I know someone said that a couple days ago, but we live about 20 minutes out of town and it wasn’t super critical. I drove the 4wd truck up and down the driveway so we weren’t stranded or anything.
Thanks everyone for your help. I learned something new with this experience.

 

[earl84]

Also played pickleball with my wife, got new tires on the truck, and saw a small herd of elk, some of them only 10 feet off the road. So it was a great day.