John Deere 425 - firing on one cylinder

walt72August 21, 2010

I have a JD425 with 20hp water cooled Kawasaki engine. It's always run strong. It intermittently started loosing a lot of power (bogging down) when mowing. I ran thru it and discovered that there's no spark on the right cylinder.

I've replaced both spark plugs & right coil pack. Piston goes up & down when turning motor by hand, & running with OHV cover off I can see that the valves open & close while running... just no spark about 95% of the time on the right side. I'm stumped. Any ideas? Thanks!

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Don't know about Kawas but B&S & Kohler V twins use a coil for each cylinder. IF your Kawa is a V twin, might look into that.

Walt Conner

    Bookmark   August 21, 2010 at 8:14AM
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***"no spark 95% of the time"***
Do you literally mean "no spark"? or are you saying "the cylinder is dead 95% of the time"?
You replaced the "coil pack" for the right bank. Does the Kaw coil have a molded spark plug cable or do you have to transfer your old spark plug cable to the new coil?
I only have the Kawasaki service manual for their FD671D thru FD791D engines, I don't know whether the JD proprietary engine is different, or not.
The wiring schematic shows the ignition system to be a very basic "magneto type, flywheel powered, grounding wire kill" configuration. Both "kill wires" converge into a single circuit without any diodes. Therefore, if either of the kill wires were chafed and shorting to ground, it would affect both coils and not just the right bank.
So, it kinda boils down to this, are you absolutely certain that you are in fact not getting spark when the cylinder is dead? Unless the old spark plug cable had to be transferred to the new coil, I don't see anything else that could kill the spark to the right bank without also killing the spark to the right bank.

    Bookmark   August 21, 2010 at 11:34AM
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Did you ever figure this out? I have a 93 425 doing the exact same thing. I replaced the coil and plug wire. Still no spark on right side only.

    Bookmark   January 27, 2013 at 8:18PM
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As mownie stated-
Are you sure it's no spark or just no run.
Verify with a spark plug tester.

Some twin engines have a 2 barrel carb, and if one jet is clogged, it only runs on one cylinder.

    Bookmark   January 28, 2013 at 7:15PM
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Good words to verify the loss of spark. Really, these can be messy or actually really simple. If you have not already installed a new set of spark plugs, now is the time to do so. Save the old plugs --carefully comparing the deposits between the two. Does it run the same warm vs cold? BTw, your particular engine should be a 1 bbl carb

    Bookmark   January 28, 2013 at 10:33PM
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Replace time delay module. About $20 from your dealer.

    Bookmark   January 30, 2013 at 10:02AM
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I have the same problem as the original post and have troubleshooted. Was the problem corrected? If so how? Was it the time delay module or something else?

    Bookmark   April 26, 2013 at 4:55PM
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I can fix your problem..All you need is to buy the time relay and KAWASAKI 21119-2157 John deere AM105574 ignitor ..Do not buy from a dealer it cost $275.00 but you can buy off ebay $97.00..But anyways that will solve your problem..don't forget this is only for those with the issue one cyl misfiring..

    Bookmark   November 10, 2013 at 10:02AM
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Nice tip.I use ECUs for the X series off Ebay which are identical to the dealers. Edit: Bummer, I thought to myself I have just one of these left after reading this thread. I see what once was 25$ shipped to my door is now over double that. :/

This post was edited by tomplum on Sun, Nov 10, 13 at 11:39

    Bookmark   November 10, 2013 at 11:30AM
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