10795 Lawnboy, Honda Engine, Can't start-- appears no spark

S

schreib69

Member
I can NOT get this thing re-started; can't figure what I may have done to mess it up. The other day I was not able to shut it off and finally figured that the lever arm with a spring on it is meant to pull the contact off when you release the handle-- it was stuck hard. I shot it with varioius cleaners(brake cleaner, WD40, etc ) then blow dried with compressed air. It now does a fine job of moving but I can't get the mower started to even test to see if that allows it to work as it should.

I am hoping for some troubleshooting help. Below are images and questions.
#1: I noticed elsewhere on this forum folks were looking for the electrical diagram-- me too. Any help with that?

My present conviction of the problem and background:
-- I checked for spark and got one at the plug.
-- I verified the shut off valve is pointed LEFT, giving flow to the carb; so I have fuel. It was last used for an hour and worked just fine until having to shut it down by closing that valve.
-- I have no reason to believe the plug is fouled or not gapped right, checked and it is OK; no reason to believe the choke is failing, verified;
-- I sprayed starting fluid into carb and can't even get it to cough. . . THAT is really odd being there is spark.
my conclusion is that somehow electrically it is self-killing during start but no idea how that could be.
-- I pulled the recoil unit and top cowl off and found some mouse bites on the coil wire (to the plug, at the coil) but it was obviously that way while I last used it.
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I can guess that maybe the micro-switch that is closed when the handle bail is closed(see image) is damaged-- from spraying stuff on it?!@$# Who knows. If damaged the switch will not be "made" when the bail handle is closed.
Other than that I have no clue here. Hope some one here does.

thanks for reading.

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Pull the coil off.

Polish the area where the screws sit, both sides and the pads where the coil sits on the engine block. Coil needs a clean ground path to work proper. Yours is all rusted up.

Better yet buy a new coil. With all the heat and vibes these mowers take. Mice chewed wires are no good.

Toss that bulb tester in the trash. Terrible for checking spark.

This one is a couple bucks shipped to your door. Allows you to SEE the spark and open the gap up stressing out the coil. Rev the engine up and see if the coil fades out at mid and high revs.

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Funny you point this out. . . THAT tester I just received days ago because the other POS could not show up a spark.(bought 18 mo ago)

THIS one initially looked bad too until I turned out all the garage lights and put black cloth behind it and taped the "male" end onto the plug wire. The "male" end is hollow, not like the solid core of a plug(and the model YOU offer up). I will ship it back to amazon and buy your suggested one! thanks.

Thanks for all the pointers, I will follow up and get back to you guys. . . gotta finish building a raised bed garden for the boss.
 
Make sure you ground the tester to clean metal. Most I see place a plug on the painted engine block and not get spark.

A simple test light can be used too. Connect the clamp to the negative battery post or clean engine block. The probe end inside your plug boot. You can move the tip away from the boot to stress the coil out.

That one I posted about is good. Can change the revs looking for a weak coil. Some coils fire okay at low revs. At mid and high they can fail. Nice to see all that happening.
 
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many are not aware that spark distance gets less and less as compression goes up. Weak spark on a plug outside the cylinder may be no spark with compression. My favorite tool for checking spark is an inductive timing light. One needs 12v for many of them. There are rechargeable battery powered inductive timing lights. You can also check the spark timing with it. If you make a couple marks when it is known good, it is easy to check for a sheared or partially sheared flywheel key.
 
I still have a dope Craftsman inductive in my box of tricks.

sgkent said:
many are not aware that spark distance gets less and less as compression goes up. Weak spark on a plug outside the cylinder may be no spark with compression.
Click to expand...
Another reason why I preach about open gap adjustable spark testers. We need to stress these coils out. Also run the engine at low, mid and high revs looking for no spark failures. Some will spark at low revs only to fail at mid and high rpm's. Then we read on here it starts fine but lacks power.
 
Interesting, you guys apparently don't use the OHMS test to check coils. . . hmmm. Maybe the reason is coil resistance is not specified ?? on many of the small engines and it is not so reliable for some reason. More likely, guessing, running the revs and watching for clues is more indicative of the real condition under stress.
It would be valuable to have a little rule set for running up RPM's and quality of spark, maybe a Utube video on it. . . Are you aware of such a thing to help me fine tune?

However, most all of this coil talk is likely beside the point, as I stated, the engine ran fine until I cleaned the lever with WD 40. . . no reason to suspect the coil; it had been starting on first or second pull, power was fine.
 
slomo said:
I still have a dope Craftsman inductive in my box of tricks.


Another reason why I preach about open gap adjustable spark testers. We need to stress these coils out. Also run the engine at low, mid and high revs looking for no spark failures. Some will spark at low revs only to fail at mid and high rpm's. Then we read on here it starts fine but lacks power.
Click to expand...
Well, if I ever get the thing running I will try to play some sparky games. . . thanks.
 
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