Craftsman mower stalling out

14 years ago

I have a Craftsman 21" mower, model 247.376380. The mower starts and runs well, but as soon as you begin cutting grass, even as short as 4", to a height of 2", the mower stalls. It does not bog, shudder, choke, or waver, it just quits, as fast as turning a switch. Even if I move the mower back from the grass or lift the front up as quickly as I can, it stops.

I've cleaned the carburetor, including running a copper wire through all the tiny venturi holes, and blown them out with compressed air. I've ascertained that the gaskets are in good shape, the air cleaner is clear, the float is floating and is not stuck, the float bowl is full, the fuel tank is full and flows VERY well, and the carburetor butterfly moves freely.

I also removed the spark plug, cleaned it and inspected it for damage, and verified the gap (0.030"). I performed a compression test, and had 90psi at 5 pulls, and close to 110psi at 10 pulls. I connected a spark checker (jumper lead with a HV neon strobe) between the coil and plug, and had a good strong spark as the mower ran.

After checking the compression, I fired the mower up again (incidentally, each time the mower quits, I have to re-prime it at least 4 or 5 pumps to get it to start again) and tied an old sock around the safety bar to keep it running. I then cleaned up all my tools and rags and whatnot while the mower ran... and ran... and ran! It did not falter even once, just sitting there it ran like a charm!

Then I started mowing with it. I made it 3 or 4 feet, and the engine quit, just like turning off a switch! The grass was approximately 5" tall.

I'm suspecting the governor vane or linkage, but would appreciate it if someone could provide their input, suggestion, advice, or ideas.

Regards,

Nick

Comments (3)

bryanbid
14 years ago
Is the blade sharp? (and the right way round)
Is the Grass wet or dry?
Is the grass accumulating under the cutter deck instead of being discharged?
Raise the cutting height, 2 inches at 1 go is a lot to take off at once.
I have no experience with Craftsman but no my Honda will baulk at long wet grass and a low cutting height.
n9viw
Original Author
14 years ago
Bryan,

* The blade is sharp, balanced, and the right way round.
* The grass is dry.
* The grass is being mulched, as it is a 3-in-1 (mulch, side discharge, or bag) but it will happen even with the open side discharge chute on.
* The cutting height is set to the second-to-highest setting. It will not stall out on grass it's barely cutting, but then it looks unkempt and I can't tell I've mowed. If I want the lawn to look decent, I like to keep it this side of shaggy.

I've little experience with Craftsman, but a friend of mine has almost always had them, and has not had the problems I'm having. Also, I have an MTD YardMan, and I can mow grass up to several feet in length (provided I go at it with the front end off the ground, thoroughly unsafe!), and it has no problem cutting grass upwards of 6" long, down to 1".

Thanks,
Nick
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tony1024
13 years ago
I has the same problem with my 6.5 HP Craftsman 21' mower. Cleaned the carburetor and start w/o the air filter but it still runs for like 10 secs and stalls.

If I keep priming it while it is running, it will keep run a little bit longer.

So I took out he carburetor once again and bring it inside the house and carefully cleaned each hole. especially the one where the needle valve fits with a thin wire. I don't have a air compressor so I blow it with my mouth :)
Also Sprayed WD40 and wiped clean.
Let it stay try with all the parts on the paper towel the whole night.
The next morning, Put back the carb.
I also replaced the plug. It was kind of dark already. So I
think what the heck...just replace it.
Replaced the air filter too.
Primed like 20 times because the carb was emptied out I think.
Then AHA it started and runs smoothly!
I cut the whole yard without any stalling!

In case you don't know what is the carburator and where it is. It is behind the air filter. So uninstall the air filter assembly.
Unscrew the two nuts.
Get the carburator out.
There is also a nut holding the bowl at the bottom of the bowl.
There is picture on the manual where it list all the key and part no of the parts.
There are holes in the jet nuts too. Clean it with wire.
Also watch some videos on ehow or u tube. I watched the ehow one and oh...that's the carb.. ok...