Mower Will Only Run With Choke ON

goose864September 6, 2009

I have a Craftsman riding mower with a Kohler 20HP (CV20S) engine. One day I ran the mower out of gas and once I fueled again, it will only run with the choke on. It runs just as it always has with the choke on (good but short on HP) and I have even mowed twice with it on since. When the choke is turned off, the mower runs for about 3 seconds (the engine even perks up as normal) and then seems to run out of gas.

I have removed, dissasembled & cleaned the carb with no change. After looking at the electrical drawings I suspect the fuel shutoff solenoid. I am going to test it for operation shortly; however, this should not even allow the mower to run with the choke on.

The fuel filter, air filter and plug have been changed. The fuel pump is working properly.

Thanks for reading and any help.

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Checked fuel solenoid, was OK as well as the power feeding it. Now I suspect the main fuel jet might be plugged, but need to verify it.

Thanks again for any advice.

    Bookmark   September 6, 2009 at 10:45PM
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Goose, I finally located the thread that you need to read.
I suspect you got some piece of trash swirled into the main jet when the refuel surge washed into the carb. Be sure you remove the jet and clean and blow out the cavity behind the main jet too.

Here is a link that might be useful: Refuel then run erratic thread

    Bookmark   September 7, 2009 at 12:28AM
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When you removed and cleaned the carb, did
you remove and clean the needle shut off valve?
I suspect dirt is holding the valve more closed
than open causing a lean out condition.

    Bookmark   September 7, 2009 at 7:20AM
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IMO the carb is still dirty or plugged up and leaning out do to lack of gas. when you pull the choke out IMO it prevents the normal amount of air entering and thus richen's up the fuel air ratio and the engine will run. other areas of problems would be any vacuum leak between the carb and intake manifold to head. Outside change it could be adjustment problem if you moved the mixture screws or they vibirated making there orginal adjustment off now.

    Bookmark   September 7, 2009 at 8:10AM
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I've had some decent luck with a product called SEAFOAM.
Not only has it helped with the California CARB non adjustable carbs that run way too lean, the stuff in the can helps stabilize fuel if your equipment sits for weeks on end

    Bookmark   September 7, 2009 at 8:49AM
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Took the carb back off, cleaned very Very VERY throughly (starter fluid & 125psi compressed air, put it back together and now its runs better than the day I bought it (used) 5 years ago. Until now, I could never idle at min throttle.

Thanks to all that replied and helped.

    Bookmark   September 7, 2009 at 8:55PM
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Can I send you 3 of my carbs? I'd love to have them running sweet and smooth

Ok, Only 2 really need YOUR touch....

    Bookmark   September 7, 2009 at 9:01PM
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just my opinion, but I would not buy starter fluid (ether) any more. you will get better results with carb. cleaner designed to dissolve and clean the carb. even if you use it as a starting fluid. It has more agents and will do a better job. Glad you got it fixed.

    Bookmark   September 8, 2009 at 6:22AM
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I had a very similar problem with my mid-90's 18hp Kohler Command. When mowing, all of a sudden it would seem like it was running out of gas and only ran with the choke full on. With the choke on, there was not even enough power to run the PTO.

When I had to refill the tank, I used straight unleaded fuel (no 10% ethanol) by accident. The problem did not come back. The next tank, I used the 10% stuff and it ran like I described above. So I switched back to the straight stuff and the problem has not come back since.

Not sure if it would help, but it's worth a shot if you use the blended fuel

    Bookmark   September 14, 2009 at 1:10PM
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rcmoser - Starter fluid was all I had at 1am. If it had not worked, I was on my way to walmart (only thing open) to get carb cleaner.

markymark-ca - Bring'em on. If I can't clean it with ether & air, I'll get out the drill and moto tool. That'll get it cleared out for sure.

    Bookmark   September 18, 2009 at 10:22PM
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I had the same problem on my JD L100 series. Tractor would only run with the choke full open. Took it into the JD dealer, he cleaned the vent on the gas cap, it was plugged and would not allow air into the system. Probelm fixed. No charge.

    Bookmark   September 28, 2009 at 5:39AM
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