Sled Cutting Out

  • Batman09
    Michigan
    Posts: 121
    February 2, 2009 at 9:11 pm #1213364

    I’ve got an older John Deere with an issue that needs resolved soon.
    It’ll start and idol fine. Put it on jack stands and it will run 4-5000 rpms smooth, with a few boosts higher in the 6-7k range.
    As soon as you put in on the ground I can get maybe 100yrds and it starts cutting out at speeds over 1/4 to 1/3 throttle. If I let off soon enough it catches itself, but I have to run it just above idol back to the shop.
    —–
    Took the carb off (again) and it looks clean, but we cleaned it again. I was thinking the main jet had some dirt but that wasn’t it. 130 and 135psi in the cylinders, new fuel lines and clamps, new fuel pump, new plugs, new trac, rebuilt the suspension, fresh paint) So you see, I’d really like to get this out of the shop.

    thegun
    mn
    Posts: 1009
    February 2, 2009 at 9:26 pm #743742

    hard to say for sure! sounds like everything is good until you put a load on it! maybe a few things! I assume it is a points system! try cleaning and checking clearances there! that is where i would start then check your coil!

    this is under the assumption you have checked to see all the fuel related items are good!

    is the diaphragm good in the lift pump?

    Air fuel mixture good! not to rich and the motor is loading up!

    hope this gives you some ideas on things to check! cant really say for sure without running it for myself!

    lots of smart people here! hope some one can help!

    Good luck!

    ranger520
    Posts: 32
    February 2, 2009 at 9:35 pm #743746

    What kind of carbs are on it???

    backlasher
    Fridley, Mn
    Posts: 195
    February 2, 2009 at 9:40 pm #743750

    I would start by checking the fuel pick-up line. They usually have a weighted filter on the end, so check if it’s plugged or off and not staying down in the tank. Also I would check the carb vent lines to make sure they are clear. It sounds like a fuel starvation problem, so if these don’t do it, one of the carb passages are plugged. Maybe the nozzle or needle and seat. Good luck.

    Batman09
    Michigan
    Posts: 121
    February 2, 2009 at 10:27 pm #743775

    1980 JD trailfire with a 440 (ta440a)
    Sorry, I should have said it has a CDI box. Is there a way to check the ignition coil?
    Single Makuni VM slide carb. But I really want to say the carb is OK

    johnie1610
    Eau Claire, WI
    Posts: 121
    February 2, 2009 at 10:54 pm #743786

    sounds like your cdi box to me or a coil. But I’m leaning towards the cdi. I had a dirtbike that did the same thing! You could ride it around warming it up and even trail riding but when you needed the juice like climbing steep hills it acted like a fouled plug just no beans.

    mallard_militia
    Fulton County, Illinois
    Posts: 1108
    February 2, 2009 at 11:13 pm #743796

    I see you were in the carbs. How did the needle and seat look on your float? You could be loading up with fuel. Are you plugs really wet? Does it run half choked? Does it backfire?

    Batman09
    Michigan
    Posts: 121
    February 2, 2009 at 11:38 pm #742585

    Quote:

    I see you were in the carbs. How did the needle and seat look on your float? You could be loading up with fuel. Are you plugs really wet? Does it run half choked? Does it backfire?

    no backfire at all, new plugs haven’t been ran long enough to show color but the old ones were dark tan and dry after running.

    ranger520
    Posts: 32
    February 3, 2009 at 12:36 am #743820

    When it starts to bog with it keep running if you choke it?? If so you have a plugged jet in there.

    big_g
    Isle, MN
    Posts: 22538
    February 3, 2009 at 12:41 am #743822

    Its been awhile since I tackled a bogging sled issue, but I would definitely lean towards a carb issue. In the jack stands, if you pin it, it will run fine ? Why it does not bog down on the jack stand does not make sense. If it did, then its time to get the starting fluid and see if that keeps it running instead of bogging. Good luck

    big G

    trumar
    Rochester, Mn
    Posts: 5967
    February 3, 2009 at 12:55 am #743824

    Just fix a polaris with the same EXACT issue ….

    water in the fuel, removed tank and cleaned, now runs as good as a Polaris can

    Just a thought

    Batman09
    Michigan
    Posts: 121
    February 3, 2009 at 1:19 am #743833

    Quote:

    When it starts to bog with it keep running if you choke it?? If so you have a plugged jet in there.

    tried this, it didnt change.

    I’ll check the tank filter and fuel tomorrow. Be nice if this was all it was. If not my guess is the cdi or ignition coil. I’ve read mixed things about the cdi boxes. Some say that they are either bad or good.

    Jack Pine
    East Central MN
    Posts: 6
    May 30, 2009 at 12:47 am #780440

    I am not a mechanic but I had a similar problem with an old Aortic Cat. The fuel line had broken down into pieces. The hole in the line allowed debris to bypass the filter. It would start fine but when you revved it up it would suck the little chunks of fuel line in and plug the line. If you let it sit a few minutes, the suction would release the debris and it would start again but only at low speed.

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