300 lawn runs 20 mins then backfires and dies

[tomplum]

Or carbon build up for that matter. It could just be saying I'm old and I'm glad we're done mowing!

 

[coloradotrout]

The engine was rebuilt 15 years ago and not a lot of hours on it. What rpm should I set idle? I do have the service manual.

 

[CADplans]

Old JD mowers that used the Kohler "K" engine (like Model K301, K321,, etc,,) have an ignition system with a coil, and a condenser.
Both the coil, and the condenser are susceptible to doing this stall thing when they get warm,,

 

[coloradotrout]

Old JD mowers that used the Kohler "K" engine (like Model K301, K321,, etc,,) have an ignition system with a coil, and a condenser.
Both the coil, and the condenser are susceptible to doing this stall thing when they get warm,,

Yep it's one of those. Any tips on diagnosing?

 

[CADplans]

Yep it's one of those. Any tips on diagnosing?

Replace the condenser,, then replace the coil,, ONLY use a Kohler coil,, or you will be replacing it again in 6 months.

These are not "digital" components,, they age, and fail, usually slowly.
Diagnosing is difficult for a newbie,, it is cheaper to replace the components, than learn ,,
replace the points, while you are at it,,

 

[coloradotrout]

Any resistance measurements etc that can be done?

Any recommendations on sourcing parts other than JD?

 

[arto98607]

There is an in-tank fuel strainer that should be cleaned out if not done in the last few years.

I would replace the condenser.

 

[coloradotrout]

condenser #14

fuel filter; looks to be part of the valve. I'll have to crawl under and have a look. It seems to run a good while, 15-25mins, before it sputters, maybe backfires, then dies. Visually I am getting a spark however.

 

[arto98607]

I think it's best to remove the seat & the fender so you can lift out the gas tank and access the filter!
At least that's how I have done it. I also added an inline fuel filter after the fuel pump.

 

[scaredychicken]

my first thought was also about fuel, it might only have "access" to 15 - 20 min of fuel in the line. check the fuel line and adjust the idle.

looks like others have already responded with good info. all the Best