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  1. #1
    Gold Member
    Join Date
    Apr 2006
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    302
    Location
    SE, Michigan
    Tractor
    PT-422 2002 Robin eng.

    Default Runs great, but does not want to stop!

    I have searched the site to try and find an answer to my problem, but it does not look like anyone has done it.

    I have seen threads on dieseling, but I am not really sure that is what is happening to my PT-422.

    I turn the key off, with throttle on high, and it just keeps running.

    I turn the key off, with throttle on low, and it just keeps running.

    I have to use the choke to get the engine to stop!

    If throttle is on high/fast, and I use the choke it just keeps running.

    If throttle is on low/slow, and I use the choke it will then stop the engine...sometimes with a backfire, but not always.

    Has anyone had this situation happen, and have you corrected the problem?

  2. #2
    Epic Contributor MossRoad's Avatar
    Join Date
    Aug 2001
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    22,769
    Location
    South Bend, Indiana (near)
    Tractor
    Power Trac PT425 2001 Model Year

    Default Re: Runs great, but does not want to stop!

    Sounds like when you turn the key to the off position, it really isn't off. I'd check the switch first, then the starter solenoid.
    MossRoad

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  3. #3
    Elite Member DieselPower's Avatar
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    Sep 2006
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    2,761
    Location
    Fairfield, PA
    Tractor
    JD 3020, JD 4230, JD 7410, JD 2440, MF 750, NH LS170

    Default Re: Runs great, but does not want to stop!

    Yep, sounds like the ignition system is still energized.

  4. #4
    Platinum Member
    Join Date
    Jan 2005
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    629
    Location
    SW Virginia
    Tractor
    PT425

    Default Re: Runs great, but does not want to stop!

    I believe the engine is shut off by grounding out the magneto, so I'd be checking for an open circuit. It may be a broken wire, or a bad ignition switch, or a disconnected wiring plug. Good luck!

    Gravy

  5. #5
    Gold Member
    Join Date
    Apr 2006
    Posts
    302
    Location
    SE, Michigan
    Tractor
    PT-422 2002 Robin eng.

    Default Re: Runs great, but does not want to stop!

    Oh no, more "trouble-shooting"!

    Oh well, time to pencil in some "quality time" with the PT again ;~) ... but not just sure of when that time is going to be.

    For now, is it going to hurt anything if when I do shut it down I use the "choke" to do it?

    Thanks in advance to the guys of the greatest forum on earth.

  6. #6
    Elite Member SnowRidge's Avatar
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    Jul 2003
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    3,091
    Location
    East Tennessee
    Tractor
    Power Trac PT-425 / Branson 3520

    Default Re: Runs great, but does not want to stop!

    It may be the fuel cutoff solenoid.

    I assume you have the Robin, which I don't have any direct experience on, but if it is like most small engines designed for power equipment, it will have a fuel shut off valve. These are usually held open by 12 volts. When you turn the key off, a spring loaded solenoid drops and shuts off the fuel. This helps prevent running on that can be prevalent with today's engines. It may also be the only engine shut off provision on some small engines.

    Assuming you do have a fuel shut off solenoid, there are only a few things related to it that could explain the engine continuing to run with the key off.

    1. A sticking fuel solenoid, althought that alone may not be enough, if an ignition based shut down is provided.

    2. A bad ignition switch.

    3. Bad wiring, possibly because someone miswired something.

    Check and see if the solenoid wire remains hot (+12 volts) with the ignition off. It shouldn't. In fact, you can test the solenoid by pulling the wire off while the engine is running. If it continues to run, the solenoid is bad.

  7. #7
    Platinum Member
    Join Date
    May 2007
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    846
    Location
    eastern PA-lower Poconos
    Tractor
    JD2320 w/R4 $21,100 w/7.16%off

    Default Re: Runs great, but does not want to stop!

    If it uses a magneto, then the OFF position on the switch MAKES a circuit. The ON position BREAK's the circuit.
    All prop planes use magnetos so they don't have to rely on the planes electrical system. When I was learning to prop a plane (hand turn the prop to prime the engine and then spin it to start) I was taught that when the pilot yelled 'switch off' that I should think LIAR. Any break in the magneto circuit, like corrosion on the switch contacts, would mean that the magnetos were live and the engine could start.
    One time the guy priming my engine yelled 'switch off' and I verified that the switch was off and yelled back 'switch off'. Well the engine started on the first turn. He came back boiling mad until I showed him that the switch was really off.
    Eastern PA -JD2320 w/R4; 200CX w/61" bucket & Markham toothbar or JD adj forks; 46BH w/16", Imatch, ballast box & York rake-blade-scarifer, 54" front plow and trailer receiver. Case 580K w/fel+bh, mule 610XC

  8. #8
    Elite Member SnowRidge's Avatar
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    Jul 2003
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    3,091
    Location
    East Tennessee
    Tractor
    Power Trac PT-425 / Branson 3520

    Default Re: Runs great, but does not want to stop!

    I took a look at the manual for the Robin EH65, which is what I assume you have. To stop the engine, it has a diode stop block, which shorts the magneto, and a fuel solenoid, which should stop it if the +12 volts are removed.

    From what I could see, either grounding the diode stop block or removing 12 volts from the fuel solenoid should stop the engine, if Power Trac wired it according to the manual, which they may not have done.

    If it is wired as indicated, then it sounds like the ignition switch has failed on two of its circuits, while the start part of the switch still functions. That seems like an odd occurrence, but it may be the case. It would also mean the fuel solenoid is powered all the time, which would eventually drain the battery.

    Let us know what you find.

  9. #9
    Veteran Member SpringHollow's Avatar
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    Dec 2006
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    1,676
    Location
    South of Rochester, NY
    Tractor
    Power Trac 1850, NH 2120

    Default Re: Runs great, but does not want to stop!

    Most electrical problems can also be caused by a poor ground.

    Ken

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