Return to the Tractors Forum | Post a Follow-Up

Plug not firing

Posted by paul03 MA (My Page) on
Mon, Aug 23, 10 at 19:14

I have a kawasaki engine FH721V and the left plug does not fire. I replaced the ignition coil for that side along with new plugs and it still does not fire the left plug, the right plug works fine. This engine has 350 hours of work and it is 7 years old, this problem just startd. What else should I be looking for to get this plug to fire.
Thank you

Follow-Up Postings:

RE: Plug not firing

  • Posted by baymee LehighValleyPA (My Page) on
    Mon, Aug 23, 10 at 19:51

Can you see that the plug isn't firing? I had a similar problem with my Onan engine, but I think it was more of a fuel or valve related problem. It only did it on a cold start, where it would run on one cylinder until the second one kicked in.

RE: Plug not firing

As said above, are you sure there is no fire? Don't know about Kawas. but B&S and Kohler have a weird "kill wire" ass'y connecting the two coils. When a one of the diodes in this goes out, all sorts of weird things happen. I would disconnect the kill wire at the base of both coils and see what happens.

Walt Conner

RE: Plug not firing

The problem with the plug not firing started with black carbon on the engine and inside hood. I then put in new plugs gaped .030 and cut the grass for 1 hour. I removed the plugs to check their condition and found the right plug had the gray/black tint that it was firing, but the left plug was in the same new unused condition, not a spec of anything on it. As for the wiring, a wire comes from the main harnes to the right ignition coil, from that connector a second wire goes to the left coil, with nothing inbetween.

RE: Plug not firing

  • Posted by baymee LehighValleyPA (My Page) on
    Tue, Aug 24, 10 at 6:05

If you mowed for an hour on one cylinder and the non-working cylinder still has an original looking plug, I would check the compression first, and look for something broken. Your plug should be gas soaked, or gas should be running out of the muffler.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Tractors Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here