300 lawn runs 20 mins then backfires and dies

[coloradotrout]

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.

Thanks! That might be easier!

 

[coloradotrout]

Pulled fender, lifted tank. Removed gas line at fuel pump. Gas flowed good for at least 0.5 gal so assuming no gas flow issues from tank to pump. Line from pump to carb looked cracked so replaced.

Connector on one of the wires at the coil snapped when I was fiddling. Two small wires connect there. Crimped on a new one.

I did not need to lift the gas tank but did it to get a look at things. Noticed a small crack in the tank right below the recessed nut. Had noticed a leak when the tank was full. Roughed it up and dabbed jb weld on it. Maybe it works; maybe not.

Realized it has a "park brake". Somehow things are not oriented correctly so the lever does not engage underneath the way it should. Not sure how that's possible but would like to figure it out!

So no idea yet on the cause of it dying after 20m of running. Guess I'll try again and try some things at the time of failure.

 

[TractorGuy]

Recently acquired a Troybilt with a POS Kohler. It was doing the same and seemed to be running lean and overheating.

I replaced the carb, plug, air filter, changed the oil, adjusted the valves, and resealed the valve cover.

Still seems lean but continues to run.

When time allows I will probably clean the old carb and drill out the main jet a little.

Only reason I replaced the carb was I bought in a set off eBay that included the air filter, pre filter, and fuel filter for the same price TS wanted just for the air filter.

 

[coloradotrout]

If it's gravity fed fuel most likely the carb if not getting fuel but check and see if it has a fuel pump about three inch round black plastic generally screwed to the engine cover, if it has one that could be it. Back firing also sounds like a firing issue you might want to sand the rust off the flywheel and coil tips.

gravity fed to the pump ;-) pumped 4" up to the carb.

It runs for 20 minutes, then sputters; maybe runs for another few mins; then eventually dies and will not start... until it's rested for awhile (I have just waited over night). To me that does not seem like a fuel pump. I crimped on a new wire connector that was running to the coil, so who knows... will try again later.

 

[coloradotrout]

Ran it for an hour tonight. Go figure. Maybe the wire connector? Maybe draining out a half gallon of gas?

I now see a small oil leak forward and above the carb. But it's about 1/4" above the full mark.

 

[kwbretired]

I would suggest checking the spark to the plug. After the engine dies, pull spark plug wire off plug insert a screw or nail in spark plug wire then hold next to plug & crank engine. You should have a blue spark jumping 3/8” to 1/2”. If you are not getting a good spark replace points & condenser & possibly the coil. Piont gap should be set around 20 thousands.

 

[coloradotrout]

Ran fine again today. Maybe that crimp on terminal was the issue? Maybe something got flushed from the fuel line?

 

[coloradotrout]

Well. As of today it's now blowing hard out the oil fill/dipstick tube. Blows the dipstick out with a mist of oil. Exhaust valve issues? Runs normal otherwise. Kids had overfilled the oil. Could that be related? (But I don't think less oil is going to be the fix now).

 

[zzvyb6]

If your ignition is based on the 'igniter' that a flywheel element passes by, the clearance (easily adjustable) may be to large. When it heats up, the clearance becomes to great and: no spark. Unignited gas will backfire. You can test this against the weather/season, a fan on the cooling system, or a torch on the flywheel. Check your cooling system air flow to see if its contributing to your problem. it sounds all too familiar to me.

 

[coloradotrout]

I had not pulled the breather tube into the air cleaner assembly, but even with that,still a lot of crankcase pressure