Page 1 of 2 12 LastLast
Results 1 to 10 of 15
  1. #1

    Join Date
    Jun 2012
    Posts
    4
    Location
    Maryland
    Mower
    Murray

    18.5 HP Briggs and Stratton (Model #31N707) starts fine, then dies 10 minutes later

    I have a 2004 Murray 42 riding mower with an 18.5 HP Briggs and Stratton (Model #31N707) that starts without a problem, runs with absolutely no sign of problems, then after about 8-10 minutes of mowing, it dies suddenly, and will not even turn over when I try to start it. If I let it cool for about 15 minutes and try to start it again, it will turn over, but won't start. If I try again the next day, it will start as if there never was a problem , then die suddenly after about 8-10 minutes of mowing, and the whole cycle starts again. It will die completely randomly, whether I am climbing a hill, descending a hill or on level ground. It also does not matter whether I am cutting through thick grass, or making turn on a part of the lawn that has already been mowed.

    When I first checked the engine, I thought the problem was a the wire from the magneto to the spark plug had been chewed by a mouse that lived in the engine while the mower was in my shed over the winter. I replaced the magneto, replaced the spark plug, cleaned the air filter, and changed the oil.. It seemed to fix the problem, until it died suddenly and backfired a couple times after mowing about 8-10 minutes.

    Because of the backfires, I thought the carburator must need cleaning. I took off the cup of the carburator and the pin assembly. The inside looked completely clean and pristine, so I did not go through the process of taking off and cleaning the entire carburator . Besides, I don't think that it is a dirty carburator because the engine runs completely fine until it instantly dies.

    Besides the 電ead man switch under the seat, is there some other kind of kill switch that may be the source of the problem? Does anyone have any other ideas about what might be happening? Any help would be appreciated greatly.

    Again in summary, this is what I have already done:
    - Used fresh gasoline
    - Replaced the spark plug and magneto/wire assembly
    - cleaned the air filter
    - replaced the fuel filter
    - cleaned the cup of the carburator (it was so clean that I do not think that the rest of the carburator could be dirty enough to be the source of the problem)
    - inspected the 電ead man switch under the seat no signs of problems

  2.  

  3. #2

    Join Date
    Jun 2011
    Posts
    112
    Location
    Fowlerville MI
    Mower
    Ferris

    Re: 18.5 HP Briggs and Stratton (Model #31N707) starts fine, then dies 10 minutes lat

    Is there a mouse nest in the shroud around the head? Sounds like its over heating.

    Rob

  4. #3

    Join Date
    Jun 2012
    Posts
    4
    Location
    Maryland
    Mower
    Murray

    Re: 18.5 HP Briggs and Stratton (Model #31N707) starts fine, then dies 10 minutes lat

    Thanks for the reply, taxidermist.
    Yes, there was an impressive amount of debris brought in by the mouse over the winter, but the first thing that I did was to remove everything. The only viable damage was the main wire between the magneto and the spark plug had a 2" section of the insulation around the wire completely chewed through. I replaced it, but the problem persists.

    Will the engine stop suddenly and refuse to turn over if it is overheating? Maybe it is overheating for some other reason? What else could cause an engine to overheat? I just changed the oil, and cleaned the air filter (didn't replace it yet). I will take a close look for any other clogs or debris that I may have missed.

  5. #4

    Join Date
    Jun 2012
    Posts
    7
    Location
    Ireland
    Mower
    Snapper

    Well this seems to be a new one. I dont unstand how when it cuts out and u try and start it again the engine doesnt even turn over, yet ot does 15 mins later without starting. R u sure u took the blades out of gear and the machine was in neutral? If u didnt then the problem is fuel related - small blockage in fuel lines or maybe fuel tank breather blocked. Good luck

  6. #5

    Join Date
    Apr 2012
    Posts
    548
    Location
    Texas
    Mower
    Troy-Bilt Super Bronco

    Re: 18.5 HP Briggs and Stratton (Model #31N707) starts fine, then dies 10 minutes lat

    You may be dealing with multiple problems. You will have to get the problem to be evident and make some checks while the problem is happening. Make the problem happen and when the engine does not crank with the starter, see if you can rotate the flywheel by hand. Is there a click sound when you try to start the engine after it dies? We have to start somewhere and the problem(s) may be related.

    Some of the ideas that come to mind that would cause your engine to die after 8-10 minutes could be a plugged fuel tank cap, ignition coil going open, wiring damage from mouse causing intermittent electrical problem. The no crank condition could be a separate problem so lets look at the no crank after it dies.

    The problem with the no crank after engine dies condition prevents you from checking for spark so that's why I recommend looking at the no crank condition first.

    Perform the above checks, answer the questions and report your findings.

  7. #6

    Join Date
    Jun 2012
    Posts
    4
    Location
    Maryland
    Mower
    Murray

    Re: 18.5 HP Briggs and Stratton (Model #31N707) starts fine, then dies 10 minutes lat

    Thanks a ton for all the replies. I will open it up in the morning and try your suggestions.
    If the flywheel key was sheared, it would run a lot different and stall sooner than 8-10 minutes, right?

  8. #7

    Join Date
    Apr 2012
    Posts
    548
    Location
    Texas
    Mower
    Troy-Bilt Super Bronco

    Re: 18.5 HP Briggs and Stratton (Model #31N707) starts fine, then dies 10 minutes lat

    Quote Originally Posted by Pahl View Post
    Thanks a ton for all the replies. I will open it up in the morning and try your suggestions.
    If the flywheel key was sheared, it would run a lot different and stall sooner than 8-10 minutes, right?
    A sheared flywheel key would cause the engine to be out of time in regard to spark timing, not valve timing, so the short answer to your question is yes. Usually a sheared flywheel key would cause a no start condition if far enough out of time or an engine that does not run properly and it would be all the time and not intermittent. Many times when an engine has a sheared flywheel key the engine will backfire as well.

  9. #8
    Carscw's Avatar
    Join Date
    Aug 2011
    Posts
    5,346
    Location
    Georgia
    Mower
    Toro

    I have the same engine does the same thing with a new coil a new $216.00 carb I have put carb and coil on Briggs 20 hp and it ran fine for as long as you wanted to run it. So I took it to a shop as much as I hate to spend money. They said the engine is fine but it still shuts off after a few mins.

    Sent from my iPhone using LMF

  10. #9

    Join Date
    Jun 2011
    Posts
    112
    Location
    Fowlerville MI
    Mower
    Ferris

    Re: 18.5 HP Briggs and Stratton (Model #31N707) starts fine, then dies 10 minutes lat

    Things to check when it dies

    Will it turn over by hand from the crank pulley

    When you hit your key do you have power at the starter

    Also does this motor have a low oil alert ?

    Rob

  11. #10

    Join Date
    Jun 2012
    Posts
    27
    Location
    North Carolina
    Mower
    John Deere

    Re: 18.5 HP Briggs and Stratton (Model #31N707) starts fine, then dies 10 minutes lat

    Cause was a pluged fuel cap causing a vacuum in the gas tank and no fuel flow. My cap has a very small vent hole about a 1/64",and was pluged, purged it with compressed air and problem solved.

Similar Threads

  1. Briggs 20hp v twin runs 5 minutes then dies like you turn key off.
    By Joey77 in forum Briggs & Stratton Forum
    Replies: 2
    Last Post: 05-01-2013, 05:56 PM
  2. craftsman starts and runs fine, then dies?
    By gray squirrel in forum Small Engine & Mower Repair
    Replies: 7
    Last Post: 04-07-2012, 11:09 AM
  3. Briggs 17 hp starts fine, dies in tall grass.
    By Zrxpilot in forum Briggs & Stratton Forum
    Replies: 9
    Last Post: 09-06-2011, 07:39 PM
  4. Briggs and Stratton engine starts but dies right away
    By cransonb in forum Briggs & Stratton Forum
    Replies: 3
    Last Post: 08-29-2011, 03:40 PM
  5. Briggs And Stratton Snapper riding lawn mower runs but dies after 5 sec
    By dssdj2009 in forum Briggs & Stratton Forum
    Replies: 7
    Last Post: 08-29-2011, 05:04 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •