Return to the Lawn Mowers Forum | Post a Follow-Up

Older sears mower won't start / stay running

Posted by williaea pa (My Page) on
Sun, May 10, 09 at 18:55

I picked up an older mower from a friend and am having trouble getting it to stay running. If I pull the plug and hit it with some straight gas it will often start and run for 2-3 seconds - so I'm assuming I have adequate spark. I have yet to get it to run using the primer. I'm used to the Lawnboy 2 cycle primer feel and I have no clue if this engine should have that same feel (creating a vacuum feel when you prime the lawnboy). It doesn't have much of any feel at all when I push the primer. Anyways - beyond that I have pulled the head. The piston and valves are moving normally. I have pulled apart the carb and cleaned it. I have pulled the top end off and sandpapered the ignition coil and flywheel. The engine says it's a 143.986700 (model) from 1998. I'm guessing it's a tecumseh engine as I've worked with Briggs engines a little bit and this doesn't look like one (But I'm not certain).

What should the ignition coil gap be for this engine?
Any clue of what I should be checking to try to get this guy running? Thanks


Follow-Up Postings:

RE: Older sears mower won't start / stay running

Magneto gap 0.01", or a business card.
Does it have a brass bolt in the bottom of the fuel bowl with orifices in it? Take it out and clean them, including possibly a tiny one near the top of the bolt - use wire tie wire to rod it out, then blast with carb cleaner.

RE: Older sears mower won't start / stay running


Thanks for the advice. Unfortunately after a week of being deathly sick (OK not quite dealthly - but sick enough I didn't feel like screwing with the mower) I pulled it apart last night and unfortunately it has no brass bolt. Carb bottom is black plastic, main orifice appears to be white / yellow plastic. Couple springs. Did carb clean stuff out and wire tie wired some openings, but no luck. Main jet orifice seems to have a black rubber gasket on it. Doesn't look great - but should be good enough to seal. Any other ideas? .010 was my original guess when I had the magneto off a couple weeks ago so that should be OK. Thanks.


RE: Older sears mower won't start / stay running

  • Posted by baymee LehighValleyPA (My Page) on
    Wed, May 20, 09 at 11:25

Does that carb use a diaphragm? Replace it?

 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 Lawn Mowers 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