Craftsman lawn mower does not stay running.

Model number: 917.378361

So the mower has run great for years, but last fall while mowing, it started sputtering and died (like it ran out of fuel). The tank was still over half full, so I pumped the priming bulb a few times and started it right back up. It ran ~30 seconds and died again. Did this four or five more times (so I could finish mowing) and then put it away for the winter. I didn't have time to work on it then, but here we are in the spring and it's doing the same thing.

It fired right up last weekend, ran for 30 seconds, then died. After reading these forums a bit, I removed the carb, cleaned everything I could and replaced a few gaskets. Still only runs for 30 seconds. I removed the carb again, cleaned out every little hole in it, including the bolt on the bowl. Sprayed carb clean through each hole and then compressed air. Same problem. Not sure where to go from here.

 

Do you have a fuel filter ?

Could there be debris at the bottom of your fuel tank plugging it shut after 30 seconds or a minute of usage ?

 

May sound silly, but remove the gas cap and try it again.
There's a tiny vent in the cap that can get plugged up.

 

Not silly at all . . . . it's one of the first possibilities mentioned in the troubleshooting sections of Owners' Manuals; but it's still overlooked !

 

Try pinching the fuel line closed with a pair of pliers. Remove the bowl from the carburetor and put a cup underneath it. Then unclamp the fuel line. Do you get a good stream of fuel coming from the carburetor?

 

Do you have a fuel filter ? No filter

I removed the gas cap, it still only ran 30 seconds or so.

I pinched off the fuel line and removed the carb bowl, there was a good steady stream coming out.

 

The cable that goes from the deadman bar to the engine... follow it to the switch on the engine. Hold the handlebar down and then help the switch activate a little farther by hand, then without letting go of the bar, crank it and see if it will run without shutting down.

 

Just tried that, seemed to run a bit longer, but still died.

A little more information here.
The mower runs great for the first 20 seconds or so, but soon begins to adjust rpm drastically for 10 to 20 seconds then dies. I watched the carburetor while the rpm's were throttling up and down, so I stuck my finger on the shaft throttle (I think that's what they call it, the little black lever on top of the carb attached to the throttle plate). I held it there solid so it couldn't adjust itself and the mower stayed running. But as soon as I released it, it proceeded to die.

 

It's running out of gas. Something is still restricted. Use torch tip cleaners to clean the tiny hole in the center of the bowl nut.

 

I've really done this at least 6 or 7 times now, there's gotta be something else. Bout ready to dumpster the whole thing.

Not sure if you will be able to see it on this picture, but there's only 2 holes in that bowl nut, one right below the threads, and one down through the center. The pic shows my torch tip cleaner down through the middle, seen through the side holes.

 

The governor hunting is due to lean fuel mixture. Check to be sure the o-ring is behind the carburetor, sealing it to the intake. While the carb is off, try wiggling the intake tube and see if it moves. If so, it could be broken or loose at the engine. It happens occasionally.

How fast does fuel dribble through the carb with the bowl off? Is it a good solid stream, or more of a dribble? It should be a good stream. Does the bowl have a dent in the side? I have seen instances where a dent in the bowl interfered with float operation, not allowing the float to travel properly.

Did you spray carb cleaner through the bowl vent (the hole on the edge of the opening in the carb) If so, it should spray into the bowl freely. If not, it won't allow the bowl to fill with gas properly.

 

Finally got back around to working on it, was busy for the last week. Anyway, my lawn needed mowed desperately, so I just ran it for 30 second intervals, mowing as fast as I could. Then about halfway through mowing, I was getting frustrated with it and just throttled it up really high for about 3 seconds as it was about to die. Ran perfectly after this. Not sure what the problem was, but it fixed itself. Guessing something was still lodged in there and just blew out. Anyway, thanks for all the help! Very appreciated.