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JP10

Process of elimination for B-10

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JP10

So I rebuilt the engine on my B-10 about 4 years ago and it has run great until now. It just does not want to start.

This is the equation:

It will turn over, I have no spark, when I hold the spark plug wire it does shock me pretty good.

Solutions tried so far:

New spark plug, unhooked key switch wire, it has a Megafire system so points/condensers are non factor.

A new coil was put in when I rebuilt the engine so I don't believe it would be that either. I suppose it could be a sheared flywheel key or maybe a bad connection with a wire but the wires appear alright. Perhaps the Megafire system went bad but I'ver never heard of them going bad.

I'm hoping that I'm missing something real simple but I fear I may have to pull the engine to get to the bottom of it. What do you guys think? What am I missing?

I appreciate your responses,

J.P.

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fishnwiz

Start cheap and replace the plug 1st..My guess would be coil as I have heard of others with similar issues and it ended up being the coil. Do you get a good spark on a plug tester?

Just for the heck of it, if you have a compression tester handy check that... I had similar issue on a b 10 but mine ended up being a head gasket that burned thru in a small area,(one time on a new gasket) therefore no compression and no start symptom. This happened to me two times on two different tractor, both b-10s. Just a thought!

Wiz

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MysTiK

random thoughts from someone who knows little about electrix. Your description of your analysis is very good.

not saying the mouseword.

ignition switch

clean regulator ground

static timing (engine)

key could be that you feel "sparked"; but have no spark. that made me think timing. No visible spark on plug? Try a third plug?

and last time I muttered "regulator ground", it led to a problem being fixed

did you change anything else lately ?

megafire doesn't fail - but maybe check the install again

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JP10

I went ahead and replaced all the old wires and cleaned all contact/ground points. I even added a new regulator that I had in the parts box. Tried three different plugs and still no visible spark but received another good shock. Megafire wires look good also.

I guess it would have to be the coil right? That would be the only thing left that I can think of. That coil is only about 4 yrs. old. Would a bad amp gauge do it? I already took the key switch out of the equation and that wasn't it either.

Any other ideas before I pull this sucker out?

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JimDk

JP, How the h**k have you been? Are those boys driving the B-10 yet?

I'd try another megafire. If you are getting shocked your coil is producimg. You do have a strange situation. If you had points and condenser, I would suggest trying an external coil. That is my solution to a bad coil if I don't want to pull the engine.

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JP10

Hey Jim,

Good to see that you're still lurking about.:D The tractor isn't fast enough for the boys so they have a go kart now. They sure grow up fast.crk8

I believe I'll try to swap out my ammeter, it isn't even moving when I try to start. I guess a bad one could keep it from starting. Also, never heard of the Megafires going bad but may have replace it next to rule it out. I'm trying to do everything I can to keep from pulling the engine.

Frustrating!yell

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RayS

Make sure the mega fire has a good ground. I don`t understand how you have no spark but get shocked holding the plug wire.

I would check head gasket and carbon holding one of the valves open or both. I have also seen rust on the flywheel magnet cause no spark to a weak spark. My Stihl 028 does this quite frequently.

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gwiseman

JP

If you get shocked there should be enough fire from the coil. Like Ray I'd check mega fire ground as well as clean engine ground. My b-10 w/novaIi is quirky; it fires at spark plug only after when starter button is depressed while engine is turning over. I've learned to start it by depressing the starter button quickly after engine starts spinning. It doesn't fail me and runs great but still has that quirk. I burned 2 coils out bf figuring out the combination.

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JP10

Well, I cleaned the ground for the Megafire, all other contact points cleaned as well. I have good compression just by putting my hand over air cleaner hole on carb. I can see valve movement through the spark plug hole. All that plus everything else I did and now I don't even get a shock from the spark plug wire anymore. I guess I'm resigned to the fact that I'll have to pull the engine and address the coil.

Also, wouldn't the ammeter move when the engine is turning over?

Thanks for all your advise, I'll whip it soon enough.}:)

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RayS

Ammeter will show a disharge when engine is cranking over. It will not have anything to do with the coil producing spark. The coil (magneto or armature) produces it`s own spark when the flywheel magnet passes it.

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RayS

You say it is turning over when you push the starter button with the key on. So the ammeter is working to some extent. The ammeter may have a problem internally, but it is allowing the engine to turn over. If you were to remove a wire from the ammeter it would not even try to crank over. Does the starter generator spin very fast? A weak starter generator that isn`t spinning very fast used with a Mega Fire or Nova II ignition can give a weak spark from what I have read on here and makes since. Kent, had posted on this in the past or atleast I believe it was him. The starter generators spin slower than a ring gear type starter to begin with. Maybe the ammeter has a resistance issue that isn`t allowing the starter generator to spin fast enough to allow the coil to produce a healthy enough spark. Do you have a volt meter?

It maybe a weak coil, rust on flywheel magnet as described above or even a mouse may have snacked on it. As well as the other suggestions listed above. Bob (BLT) runs his Mega fire through his points, but it was working before now. I will quit rambling now.

Do you have a repair manual so that you can trouble shoot the electrical? Under cool links in my profile is the large frame repair manual. It is for the newer large frames but covers the older as well.

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JP10

Ray,

I appreciate your ramblings and the ramblings of everyone else. I don't mind the problems so much because it gives me a chance to learn. Already learned much through this process and by talking to you guys. I truly appreciate the shared knowledge here.

I'll get it figured out.;)

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JP10

Update:

Finally got the tractor running. The Megafire was bad so I replaced with a Nova II ignition module and it fired right up. Amazing how the smallest things make the biggest difference. Thanks to all for your insight.

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JP10

I didn't test it. I just used a process of elimination on the entire electrical system and with my luck it was the last thing to check. I changed it out and it works now. Just thankful it was a cheap fix.

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fishnwiz
quote:Originally posted by JP10

Update:Finally got the tractor running. The Megafire was bad so I replaced with a Nova II ignition module and it fired right up. Amazing how the smallest things make the biggest difference. Thanks to all for your insight.


id="quote">
id="quote">Just curious where you bought and how much was the Nova II ?

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