weedeater one 875 series riding motor wont run but turns over

hustler1979

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  • / weedeater one 875 series riding motor wont run but turns over
HI guys please help.. weedeater one riding mower won't start. it turns over, appears too have spark using a spark checker and has fuel . it may have weak spark i am not sure what it is supposed to have. it has fired a few times but will not run. appears to flood easy on carb cleaner. i took carb off and pilot jet clean and carb appears to be fine. note i was a powersports tech for many years and am not a complete noob. spark plug is new.

what should compression be?
this mower has a carb that is controlled by mechanisms that adjust choke and throttle on its own
is there anything weird these are known for in not starting?
can a seat switch affect amount of spark?
 

ILENGINE

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  • / weedeater one 875 series riding motor wont run but turns over
Compression should be 70-100 after 10 pulls of the starting rope. Seat switch not likely to effect spark quality since those mowers use relays to control starting and shutdown, but I would check fuel quality, and if questionable try changing the fuel. and try a new plug just in case.
 

hustler1979

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  • / weedeater one 875 series riding motor wont run but turns over
i have changed fuel and plug. i will check compression in morning. I wonder if it may have a tight intake valve?
it should run on carb cleaner also. i suspect a bad coil as well. Spark looks weak to me.
 
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ILENGINE

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  • / weedeater one 875 series riding motor wont run but turns over
Could be a valve issue. Also just because you have fire when the plug is outside the engine, doesn't mean it will fire under compression so it is a possibility.
 

hustler1979

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  • / weedeater one 875 series riding motor wont run but turns over
Could be a valve issue. Also just because you have fire when the plug is outside the engine, doesn't mean it will fire under compression so it is a possibility.

How does this system work with the ignition coil. Do snit have a stator with magnets and is it possible there is something covering those where the air gap is supposed to be. How do you test a weak ignition coil or check and see if stator is not putting out correctly on these?
 

ILENGINE

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  • / weedeater one 875 series riding motor wont run but turns over
The ignition module is on the outside of the flywheel and is self powered by magnetic induction from the magnet on the outside of the flywheel. There is a single black wire that goes to the module that can be unplugged from the module after removing the blower cover. Also make sure you have the correct air gap between the module legs and the flywheel. Without the exact model number of the engine I can't give you the correct gap. Some are .010-.014 and others are .006. the easiest way to check spark with the spark plug installed is with one of those blinking light type spark tester that can be purchased cheap. Sometimes they will give a fault positive, but work very well.

Be aware that if you start the engine with the kill wire disconnected from the module you can't shut off the engine without either reconnecting the wire, or using something like a screwdriver to ground the spade terminal to the engine block.
 

hustler1979

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  • / weedeater one 875 series riding motor wont run but turns over
Thanks ilengine. Model is a we261. It looks like you can adjust airgap which one should I go with ? And is that on magneto or coil for gap off the flywheel?
 

ILENGINE

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  • / weedeater one 875 series riding motor wont run but turns over
That is the model of the lawnmower What i am needing is the number off of the engine itself will look like and actually say what is typed.

Model type Code

XXXXXX XXXX XX XXXXXXXX

either on the blower housing above the spark plug or one the side, or on the flap above the muffler, or sometimes on the metal shield around the cylinder. that is the gap between the ignition module, or coil if that is what you want to call it, and the magnet on the flywheel.
 

hustler1979

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  • / weedeater one 875 series riding motor wont run but turns over
It is 12S907-1411-B1 and has 56 psi of compression
 

ILENGINE

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  • / weedeater one 875 series riding motor wont run but turns over
Module are gap is .010-.014 with a spark plug gap of .020 Most engines run a wider gap so make sure to use the correct gap. Also If you haven't all ready put a new plug in. Those plugs that they used in those engines with the narrow gap have a bad happen of just fouling out for no reason, and in a short period of time.

the plugs that they use now don't have the sealant on the ceramic so fuel will soak into the ceramic and cause a internal short to the plug. And blink type spark testers will give a false positive.
 
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