Question about Craftsman 20 Hp 42" Deck Lawn Tractor

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Craftsman riding mower, 21hp B&S starts and dies

Fresh out of the garage, mower will start and make about a lap around the yard. Then, with no warning, the engine will die. The last time I mowed, after doing this, it simply started up again and ran like a champ (as usual).

Today, after the same issue, it wouldn't start at all after it died. I went inside to research, went back out, and it started back up, only to die again about a minute later. After having pushed it back into the garage and taking time to do more research, when I go back out, the engine will start and run for about 1 second with full 'choke'.

There is strong fuel flow from the fuel filter upstream of the carb, between the fuel tank and carb. This I can guarantee.

Any suggestions?

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  • steve792 Jun 20, 2009

    This is the 6th or seventh time I have had it out of the garage this year, even though I live in an area of the US that might be considered by most to have two seasons--winter and road repair.

    After making this post, I went back out, took the fuel line off at the carb (on the very unlikely chance that the fuel intake at the carb had debris in it, which it didn't). After putting the fuel line back on, it started right up.

    Ok, it was running, and ran some more, so I started mowing. 20 minutes later (and, of course, 85% through the lawn), blamo, dead again. Same symptoms--every once in a while, she will actually fire, but only for about a second. Most of the time, it just turns over.

    I will go get a carb kit tomorrow, should I be able to find one, but the mower isn't that old, and the fuel has been drained every season when not in use.

  • steve792 Jul 02, 2009

    Ok, I pulled the carb, and cleaned it (though it didn't need it). While doing so, I resisted all urges to put an air filter and exhaust in to allow it to breathe more and rejet before putting it back together. ;-)

    After getting it back together, she ran for a while, but still wasn't right, dying suddenly at times, and not wanting to start again.

    I started thinking more about the symptoms, and how they appeared to be associated somewhat with vibration, so I checked the plug that goes to the solenoid at the bottom of the carb. Unplugged and plugged that in a couple of times to make sure it was seated, and noticed that the ground wire (black) was up against the engine block. Thinking that the heat couldn't be good for the wire insulation, I figured I would move it out of contact.

    And then, finally, when I went to do this, I discovered that the bolt holding the ground to the engine block was loose. Tightened that up to secure the ground, started her up, and VROOM!

    I appreciate, sincerely, the suggestions and assistance. I guess adding checking that connection (or adding some locktite, which I will be doing) is another step in the solution.





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Try removing fuel bowl under carb and cleaning it. Junk and condensation can collect there. I had same problem. Did that and problem fixed.

Posted on Jun 20, 2009

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Fresh out of the garage says to me this is the first time you have used it this year. There is not a very long shelf life on gasoline anymore. Plus with all the additive they put in gasoline the diaphgram in the carb could have become tough and not very pliable. Kind of like paper. If this is the case have the carb cleaned and rebuilt (as in diaphragm replaced, probably needle and seat also.) Hopefully this will solve the problem.

Posted on Jun 19, 2009


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