Engine running lean???

[Bowieeeeeeeeee 1]

Picked up a 98' 520lxi with the 20hp Kawasaki engine.  Engine ran fine when I tested the tractor. Did fine on a cold start. Could leave the throttle at low setting and would idle fine. Did a quick run around the yard at full throttle with the PTO engaged, and still no issues. Today is the 1st time I tried cutting yard with it. Again no issues until about 15 minutes into cutting grass and the engine stalled. I just changed the plugs as a maintenance precaution so I thought I got the gap wrong. Pulled the plugs, double checked gap and reinstalled. Their was no obvious signs of misfire or carbon on the tip. Once again 10 minutes later it did the same thing. I then reinstalled the old plugs just to rule the new ones out. Same thing but this time I noted the exhaust headers were glowing red and some 'sparks' would fly out from the exhaust. The engine would start back up, but would die again within a minute. If I let the sit for 1/2 hour and tried cutting grass again it would run fine for the 10-15 minutes then the cycle of shutting down would repeat. I did some Google checks and the suggestion of the motor running lean was a common response. I would like some input from you guys (& gals) as to what you believe may be going on. If it does sound like a lean issue how can I fix it? I am no mechanic by any stretch of the imagination but I try. Hopefully I can get some direction here. If I need to adjust something on the carb please provide a step by step guide and for those who are familiar with this carb where the adjustment screw would be located and do I turn it clockwise or counterclockwise. I thoroughly cleaned the tractor prior to be being used so it's not any build up of debris causing the issue. In addition the temp gauge never went into the red zone and I got no warning lights. I also cleaned both the air and pre filter. Looking forward to your expert tutelage. I really like this tractor and I'd hate for this issue to sour my opinion. Thanks...

[Bowieeeeeeeeee 1]

[Bowieeeeeeeeee 1]

[Achto 28,958]

Have you checked the vent on your fuel cap? A plugged vent could cause vapor locking which would cause a lean condition. To check this theory run the tractor with the cap loose or with a rag covering the fuel bung, use a rubber band to hold the rag on. This will keep debris out of the tank but allow it to take in air.

[8ntruck 7,474]

I agree with it being lean -  Glowing headers and sparks.  Run the engine too long in this condition is not a good thing to do.

 

If there is a strainer on the fuel pickup, you should make sure it is clean and that you don't have any crud floating around in the tank.  Might be the strainer picks up crud as the engine runs until it starves the engine.  When you shut the engine off, the fuel pump stops and the crud might fall off of the strainer.

[Tuneup 1,441]

That shut-off solenoid at the base of the carb can likely be unscrewed and will reveal the main jet. Who knows what crud might also flow out of there.

[ranger 1,783]

I have a “Westwood” D1200, Lombadini Diesel engine. The P.O. Had spent a lot of money trying to cure this same problem, new injector, etc. It would run for an hour then die. Leave it for a while, same thing. I was given it for nothing, Sister in Law. It turned out to be the fuel tank outlet “stalk” had been crushed by the hose clip and was restricting fuel flow!

 

Doug.

[Bowieeeeeeeeee 1]

Thanks to all that have responded.  I will definitely follow-up on all the suggestions. I'm leaning on the fuel filter now. It looked pretty old and I went to replace it but found out it was 1/4" barbs not 3/8" that I ordered. Maybe I stirred up some crud when I was moving it around for removal.