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Stupid friggin gas engines!

BigBlueChevy

BigBlueChevy

Compression Ignition Addict
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ok so its not a GM big block... or a small block... or hell even a 4 banger... but it is gas and I really see know where else to put this.

We have an MTD yard machine 10hp 2 stage snow blower with electric start(plug in) The damn thing refuses to start. Not even a sniff of ether is waking it up. Diagnosed it the best I could on a what I figured made sence since gas isn't my thing.

-fuel isn't the problem. I've got fuel in the tank(fresh), full present in the carb. and the primer is working. 5 seconds of cranking has the spark plug bottom wet with fuel.

I pulled the spark plug and pressed it against the frame over the bore to try and get it to spark. Nothing. Tried a different spark plug, nothing. Tried cleaning the gap to clean it up a little, no difference.


I hate gassers. Is there something I'm missing? Why can't it all just auto-ignite like a diesel?
 
how old is the machine
when was the last time it ran

no spark = bad plug, cracked wire, bad "generator", depolarized or very corroded magnet on flywheel, wrong gap on flywheel. That's pretty much it for components.

Make sure the spark plug boot is actually connecting to the plug. They sometimes can twist inside and not snap on the plug right.

If your sure the plug, plug boot, and wire is good I'd lean towards the generator. Trace the plug wire back to whatever "black box" it goes into and that's your generator.



ak diesel driver's post wasn't there when I first typed. Definitely would check that first :D Make sure the insulation isn't cracked and grounding out on some metal.
 
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not sure on age. And I can't seem to find any kind of date on manufacture on it anywhere. I would go out on a leg and say about 10 years?

Last time ran was last year. I drained the fuel then refilled it with fresh fuel yesterday.

Before you guys posted I went out and tore deeper into the motor. Pulled the pull starter off and the cover that houses the flywheel where the ignition wire disappeared into.

Found the generator and the magnet on the flywheel. Cleaned up the magnet as it had a little surface rust, but nothing that would stop it from getting the "point across" so to speak. I pulled the "ground wire" coming off the generator and tried the spark plug again. This time, with direct contact to the ground pin on the generator. Hit the starter and got it to arc every revolution

I routed a direct grounding connection to the block and right next to the spark plug as you can see in the pictures I attached. I could not get the plug to arc without directly touching that ground pin on the generator. I checked my connections, which are good, so this basically leaves me thinking that the generator is on its way out?

I have found no deformations in the ignition wire and the fact that it is arcing via direct connection to the generator means there must be a sufficient connection inside the plug boot.
 

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It leads me to believe that a safety switch is engaged, this will cause a no start, does it have something like that? If you have a helper who will hold onto the spark plug and while you gently pull on the starter he should yell at you if it gets any spark, or if you have a starter motor just bump start and see if you have anything. Most are electronically controlled now you may have to figure that in.......just kidding on the spark plug, ifit does fire while someone is holding it they will do more than yell at you....lol
 
SfcJones said:
It leads me to believe that a safety switch is engaged, this will cause a no start, does it have something like that? If you have a helper who will hold onto the spark plug and while you gently pull on the starter he should yell at you if it gets any spark, or if you have a starter motor just bump start and see if you have anything. Most are electronically controlled now you may have to figure that in.......just kidding on the spark plug, ifit does fire while someone is holding it they will do more than yell at you....lol
Click to expand...

I would usually believe that, except that I bypassed ALL of the cuttoffs by running a direct ground wire from the generators prong to 2 points on the block. One in which is not more than 2" away from the spark plug. No matter what I tried I could not replicate the results. It wouldn't spark without the plug being in direct contact with the prong on the generator.

It is electric start so thats how I as able to "bump" start it myself and determine the above mentioned. I'm going to stop by lowes tomorrow and pick up a new spark plug to see if that alters the effects at all. If the same thing happens, I'm going to blame the generator.

Ed, no its not a Briggs.
 
Very true. Back from my MX days, if a resistor plug would foul it shorted out and would never spark again.

OP, did you want to put this in the 6.5 section where more people will be likely to see it by any chance???
 
I vote for a fouled/defective plug.

On the rear of the gear case, left had side, there should be a model number placard. This should have the engine model as well.

Here is a source for parts, or at least part numbers.

www.partstree.com

It's good for most MTD products, may not be the cheapest, or the quickest. But the diagrams and p/n's can be darn handy.
 
Sorry I'm so late to chime in... I've been surfing with my phone and the pics were too small.

If I remember correctly, that engine had a kill-KEY that was right beside the choke (that red-dial-on-a-rod that comes out of the carb)... the plastic 'KEY' slipped in between a couple of contacts - one leading to the magneto and the other leading to ground - that had to be kept separated in order for the spark to reach the plug.

Look for that - if your engine has a slot for that, then it is likely that the mag is grounding out, as |Tim suggested above. Put something non-conductive between the contacts to break the ground circuit, dump a bit of gas (DON'T us ether!!) into the sparkplug hole, and start 'er up.
 
It is a Tecumsah actually. I'll go out and pick up a new spark plug and see if that wakes the damn thing up. Not having it has been killing us this storm since I was to sick to drive the plow trucks

Saratogo I was actually trying to keep it within thread specific stuff but hell if you hav no problem with it I sure won't.

I'll replace the plug and report back on my progress.
 
BigBlueChevy said:
It is a Tecumsah actually. I'll go out and pick up a new spark plug and see if that wakes the damn thing up. Not having it has been killing us this storm since I was to sick to drive the plow trucks

Saratogo I was actually trying to keep it within thread specific stuff but hell if you hav no problem with it I sure won't.

I'll replace the plug and report back on my progress.
Click to expand...

Just yankin your chain. :thumbsup:

Let us know if the $1.99 plug solves the problem!
 
I have the same type of blower. Bought it new in '95 and it's been rock solid in every way. All you guys have some great ideas. IMO make sure the plastic key is doing it's job like Jim says, and of course try the new plug. From there, I'd pull the float bowl off and make sure the needle isn't stuck. Could be flooding so bad that it wets the plug...

Good luck.
 
JiFaire said:
Sorry I'm so late to chime in... I've been surfing with my phone and the pics were too small.

If I remember correctly, that engine had a kill-KEY that was right beside the choke (that red-dial-on-a-rod that comes out of the carb)... the plastic 'KEY' slipped in between a couple of contacts - one leading to the magneto and the other leading to ground - that had to be kept separated in order for the spark to reach the plug.

Look for that - if your engine has a slot for that, then it is likely that the mag is grounding out, as |Tim suggested above. Put something non-conductive between the contacts to break the ground circuit, dump a bit of gas (DON'T us ether!!) into the sparkplug hole, and start 'er up.
Click to expand...

I forgot all about the safety key.... but that would be too easy.
 
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