# Tecumseh HM80 with no spark



## arcticcatmatt

Hey guys. Neat forum you have here. 

My father had an old sears craftsman snowblower that would not start. He bought a new one and gave the old to me. 

I have spent all night working on it and reading things online. Here is where I am at. 

The thing has no spark. I put a new plug it it and still nothing. I took the flywheel off and sanded the slighty rusted metal contacts that come close to the flywheel magnets, still no spark. 

I then thought points. I know snowmobiles but not these four strokes. I undid the stator/magneto bolts that hold it on. I thought I had to to get to the points. Anyways, I undid the wire that held the aluminum cover on and got to the points. The gap seems to be .020 which is in spec. I got a little piece of 2000 grit sandpaper in there and lightly sanded them. I put the stator/magneto on just as I got it off. The bolts left circles where they mounted so the timing should still be the same. 

Still.. no spark. I am at a loss. Can anyone assist me is resurrecting this old beast? 

Thanks for your time! 
I did notice that there is only one wire leaving the ignition switch. On snowmobiles there are two. I cleaned where this wire attaches with no luck.


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## Maytag

I'll take a stab...........(however be aware I'm a self taught weekend backyard mechanic and very new at this game)

Capacitor (condensor) bad or has corroded connection so it's not charging?
Not sure? I would replace it while you have the flywheel off. Only like a buck or 2.

Kill switch wire shorted to ground somewhere other than where its supposed to be to shut off engine.....under a shroud where its insulation is worn or otherwise pierced?

That's my penny. At least something to look for until the pros are able to respond.

Good Luck

Maytag :drunk:


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## arcticcatmatt

^ Thanks. 

Someone told me on another forum to move the throttle, it looks like it is closed in the picture. I moved it and the damn thing has spark. Never seen this in an engine. 

Now, to go get this baby running.


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## arcticcatmatt

Well, it runs but only if I keep putting my hand over the carb inlet while on full choke. Remove my hand and it dies.


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## paulr44

I agree with Maytag - solid advice. You have the flywheel off, you should replace both the points and the condensor - both only run about $10 to $12 retail total. Gap the points at 0.018", when you tighten the screw they'll open up to the correct gap of 0.020". Oops, just let one of my little secrets go...for antique restoration anyway!
If the points have a black rubbing block, they should DEFINITELY be replaced. They had a history of the spring connection loosening up by the point contact.

If you look at your pictures, the red wire that connects to the black wire and goes up by the carb. is the ignition kill circuit, operated by the throttle control
Now you need carb. work. An adjustment of the high-speed mixture screw underneath the carb. may be enough is there isn't much gum in the carb.
Paul


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## arcticcatmatt

^ Thanks. 

I got the carb off. I have some parts soaking in cleaner overnight. 

I noticed that the float has a pinhole. Actually two. I am trying to figure out what float I need now. I know its a series 3 techumseh. 

When this baby runs I will make a video and post 

I am finding a float locally tomorrow I hope.


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## Lawnmowertech

arcticcatmatt said:


> ^ Thanks.
> 
> I got the carb off. I have some parts soaking in cleaner overnight.
> 
> I noticed that the float has a pinhole. I am trying to figure out what float I need now. I know its a series 3 techumseh.
> 
> When this baby runs I will make a video and post


Tecumseh # 632019

Points # 30547A 

Condenser # 30548B 

hope this helps you at least saves you a headache in trying to figure out what the part #s are


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## arcticcatmatt

^ Thanks! I will buy an entire carb rebuild kit if I can get one. 

I am looking at an online diagram and some floats have springs, some done. The spring goes on the pivot pin. Mine had no spring. I am wondering if it was supposed to.


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## Lawnmowertech

i can supply you with a part # for a kit i just need some info off the engine blower housing there should be a 5 digit # followed by a letter on that blower housing may say Spec in front of it it will be right after the HM80 that tells what carb it has etc. thanks 
calvin


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## arcticcatmatt

^ Not needed now but thank you! I got a kit from the local dealer. 

I just rebuilt the carb and set everything to the factory specs. It also now has a plastic float in it. 

It is sooooo close to running. It will run on full choke on its own for about a min. As soon as I go to take the choke off it dies. 

I went to adjust the throttle and my cable broke. It was working perfect the stupid thing. Now I am hoping to locate a cheap throttle cable. I don't want to put a ton of money into this thing, it is a ticking time bomb I think. 

The damn float and rebuild kit cost me 23 bucks hah.


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## arcticcatmatt

I rigged the throttle cable just to try and do the driveway. 

No go. The thing backfires and shoots flames out of the carb. It will only run on full choke. 

I am about to give up on it with a for sale sign.


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## Lawnmowertech

arcticcatmatt said:


> I rigged the throttle cable just to try and do the driveway.
> 
> No go. The thing backfires and shoots flames out of the carb. It will only run on full choke.
> 
> I am about to give up on it with a for sale sign.


hmmmmmm a big ole hmmmmmmmm sorry to hear that that flame throwing thru the carb is telling me we have a ignition or valve problem with the motor 


run on full choke so the motor will spit flames on throttle down ? 

and start backfiring ?

do me a favor check the inline fuel filter to see if it is plugged up ?

also make sure there is no water in fuel 

as well the needle under the bowl looks to me it is a valve type needle that carb did you clean and soak it before you installed the kit ? 
let me know 
calvin


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## [email protected]

Hello all! My first post. Well I don't know what to do next. I have a 4hp Ariens (Techumseh engine). I think it is a HM80 (the carb in the above pic is exactly what I have). Here is a run down of what I have done so far: I have soaked the carb for a total of 4-5 days off and on (many attempts at rebuilding it), put in a rebuild kit, have the float in tolerance, I took off the head and cleaned the carbon off the valves, I have strong spark, 93 octane fuel in a clean fuel tank, used the fuel in the spark plug hole trick (new plug), I tried starter fluid. Used the water trick and everything is allowing the water to flow. Blew out the carb with compressed air, reassembled and nothing. My question is what else is there to try and... what is the deal with the wire coming from the the flywheel? If I connect it it stops giving me spark, strong spark without it. Help, I totally rebuilt the whole machine and put alot of hours doing it, very bummed my work is all for not at this point. 
Thank you in advance for your help.


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## arcticcatmatt

Lawnmowertech said:


> hmmmmmm a big ole hmmmmmmmm sorry to hear that that flame throwing thru the carb is telling me we have a ignition or valve problem with the motor
> 
> 
> run on full choke so the motor will spit flames on throttle down ?
> 
> and start backfiring ?
> 
> do me a favor check the inline fuel filter to see if it is plugged up ?
> 
> also make sure there is no water in fuel
> 
> as well the needle under the bowl looks to me it is a valve type needle that carb did you clean and soak it before you installed the kit ?
> let me know
> calvin


Yes. Full choke, motor runs but will back fire every few seconds and shoot flames out of the carb. Sometimes it will keep running, sometimes it will die. There is no inline fuel filter on this unit. There is no water in the gas, I put the gas line and fuel tank on myself that were empty. 
The needle and seat in the carb are brand new with the rebuild kit, so is the part in the bowl. 

How do I check the valves on this motor? Maybe I have a sticking valve? 

Thanks a bunch for the reply!


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## Hack

The engine and blower are worth the effort to save. I just "purchased" a similar system. now that I got it running, I can throw snow nearly 20 feet.

It may be the timing is off slightly but it sound more like the carburetor needs adjusting. There are two screws for this.

The slow idle screw on the side of the carb between the two small bolts holding the cover mounting bracket. This should be turned all the way in a backed out one and a half turns.

The main idle screw on the bottom of the float. After fully turning it in back it out 2 turns to get it in a ballpark. Then fire up the engine and fine tune it from there.

good luck.


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## dt4ts3

I am dealing with a Tecumseh 8 horse with no spark. I've gone through what has been discussed here to no avail. If the coil itself is bad and I have to remove the coil and such, how hard is it to re time the engine? Is there something I am overlooking? I have an Ariens snowthrower, the ignition switch is broken, but I have isolated the engine from the blowers circutry as part of my problem solving.


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## Elmo31

you may have lacquer on valve stems from previous old gas....Get it running and hot, fast speed, squirt Automatic tranny fluid into carb, It will smoke like hell and slow down....Repeat two or three times, then keep squirting until she stalls.....Let set overnight. If this doesn't run OK, then you need a valve job.....This ATF stuff has worked for me many times.....ET.....


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## paulr44

If the coil is isolated from any grounding circuitry, and is gapped correctly away from the flywheel (0.0125), is mounted correctly (some are directional), the tester you're using is "known good," and still no spark, then process of elimination says it's a bad coil. They're not very expensive though...
Paul


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