Suddenly running Rough and Stalling

[FalconStig]

After 40 minutes of use my Craftsman Riding Mower (engine in rear) suddenly started to run rough and stall. It would restart and die immediately. Left it while I finished lawn with my walk-behind. After 1/2 hour, started rider again but continued to run rough long enough to get back to the garage. Replaced spark plug, fuel filter and checked oil level, fuel level and fuel for contaminants/water. No change. Carb was off and rebuilt at start of season. Was running great! Suspecting bad coil. Planning to replace coil but would like to know what VOM readings for a good coil to confirm defective.

Engine Specs: 10 HP
Engine Model 143.001000
Engine Family: YTPXS.3582CA
Displacement: 368
DOM: 0028A

Thanks for any info and/or advice,, Rob

 

[Bertrrr]

If it's firing and starting up - it's not your coil in my opinion, I think you have a fuel issue somewhere , coils either fire or not , fuel problems however behave like you're describing

 

[Rivets]

Coil part number is 35135B, but I wouldn’t purchase a new one until I did a little more testing. I would purchase an inline spark tester, most auto parts stores have them, and test to see if you have an inconsistent spark. You cannot test today’s coils unless you have expensive equipment. As stated I also think you have a few problem. When you checked the oil level, did you check if it smelled like gas? What did the old plugs look like, black, brown or white? How did you test for water n the fuel? I normally take a clean glass bottle or jar, disconnect the fuel line at the carb and fill the jar 3/4 full. Put the top on tight and shake the jar vigorously. If the fluid turns cloudy, water mixture. To verify, let the jar sit for 5 minutes and check for separation. Water is heavier than gas and will settle to the bottom.

 

[FalconStig]

Checked fuel by draining a pint into a bottle and looked for separation. None noted. Oil was actually about 6 oz. low (topped it off) and no smell of fuel. With clean fuel and clean fuel filter (I cut it open to inspect) I’d be surprised if it’s the carb but will pull it and disassemble tomorrow. Thought it might be coil breaking down due to heat but still ran rough after cool down. Will rebuild carb (again!) and will report back. Thanks for the input. I’ve learned a tremendous amount lurking since I joined and appreciate everyone sharing their knowledge and experience.

 

[FalconStig]

Checked fuel by draining a pint into a bottle and looked for separation. None noted. Oil was actually about 6 oz. low (topped it off) and no smell of fuel. With clean fuel and clean fuel filter (I cut it open to inspect) I’d be surprised if it’s the carb but will pull it and disassemble tomorrow. Thought it might be coil breaking down due to heat but still ran rough after cool down. Will rebuild carb (again!) and will report back. Thanks for the input. I’ve learned a tremendous amount lurking since I joined and appreciate everyone sharing their knowledge and experience.

 

[bertsmobile1]

Low oil
So that is a hint
Check the valve operation & valve lash
Check the height of the valves, they all should poke out the same amount as they are the same lengths.

 

[FalconStig]

Low oil
So that is a hint
Check the valve operation & valve lash
Check the height of the valves, they all should poke out the same amount as they are the same lengths.

Sorry no update yet. Sudden health issues. Will update when I know more.

 

[Rivets]

We’ll be around when your health improves. Most guys never post back and we do wonder what happens, so your post is a plus. Health is more important than any tractor, GET WELL SOON.

 

[FalconStig]

We’ll be around when your health improves. Most guys never post back and we do wonder what happens, so your post is a plus. Health is more important than any tractor, GET WELL SOON.

First, thanks for the well wishes. Feeling much better. Well enough to pull the carb and run it through the ultrasonic cleaner once again. Ran some welding tips through all the orifices and found a plugged pilot jet. Cleaned it out, put it back together and reinstalled it. Runs like a champ! Thanks for everyone’s input.