Pulsing lawn mower

Discussion in 'Home Repair' started by Calab, Aug 9, 2009.

  1. Calab

    Calab Guest

    Howdy!

    I just received a three year old B&S 3.5 horsepower mower from a friend.
    Currently, it starts easy but starts pulsing once it's been running for a
    few minutes.

    I've been told that the mower ran fine until it was tipped onto it's side to
    be cleaned out.

    What I've done so far...
    - cleaned the sponge air filter
    - drained the gas and filled with new
    - sprayed the carb with carb cleaner
    - checked oil levels
    - ensured that the throttle moves freely

    The only thing that I can think of is that it's internal to the carb, or
    that the springs on the carb are not in their correct location.

    Photo's of the carb and linkage.

    http://members.shaw.ca/linkto/temp/carb1.jpg

    http://members.shaw.ca/linkto/temp/carb2.jpg

    Any ideas on how to fix this?
     
    Calab, Aug 9, 2009
    #1
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  2. Calab

    RBM Guest

    "Calab" <> wrote in message
    news:X9Hfm.90048$...
    >
    > Howdy!
    >
    > I just received a three year old B&S 3.5 horsepower mower from a friend.
    > Currently, it starts easy but starts pulsing once it's been running for a
    > few minutes.
    >
    > I've been told that the mower ran fine until it was tipped onto it's side
    > to be cleaned out.
    >
    > What I've done so far...
    > - cleaned the sponge air filter
    > - drained the gas and filled with new
    > - sprayed the carb with carb cleaner
    > - checked oil levels
    > - ensured that the throttle moves freely
    >
    > The only thing that I can think of is that it's internal to the carb, or
    > that the springs on the carb are not in their correct location.
    >
    > Photo's of the carb and linkage.
    >
    > http://members.shaw.ca/linkto/temp/carb1.jpg
    >
    > http://members.shaw.ca/linkto/temp/carb2.jpg
    >
    > Any ideas on how to fix this?



    The condition is called "hunting", and is caused by a governor that needs
    adjustment
    >
     
    RBM, Aug 9, 2009
    #2
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  3. Calab

    Oren Guest

    On Sun, 9 Aug 2009 15:26:14 -0600, "Calab" <> wrote:

    >
    >Howdy!
    >
    >I just received a three year old B&S 3.5 horsepower mower from a friend.
    >Currently, it starts easy but starts pulsing once it's been running for a
    >few minutes.
    >
    >I've been told that the mower ran fine until it was tipped onto it's side to
    >be cleaned out.
    >
    >What I've done so far...
    > - cleaned the sponge air filter
    > - drained the gas and filled with new
    > - sprayed the carb with carb cleaner
    > - checked oil levels
    > - ensured that the throttle moves freely
    >
    >The only thing that I can think of is that it's internal to the carb, or
    >that the springs on the carb are not in their correct location.
    >
    >Photo's of the carb and linkage.
    >
    >http://members.shaw.ca/linkto/temp/carb1.jpg
    >
    >http://members.shaw.ca/linkto/temp/carb2.jpg
    >
    >Any ideas on how to fix this?


    Loosen the gas cap a tad and see it runs better. If so the cap vent is
    clogged. Use a paper clip to clear the cap vent hole.

    A fouled spark plug might be the culprit.
     
    Oren, Aug 9, 2009
    #3
  4. Calab

    Doug Miller Guest

    In article <4a7f47f5$0$10302$>, "RBM" <> wrote:
    >
    >"Calab" <> wrote in message
    >news:X9Hfm.90048$...
    >>
    >> Howdy!
    >>
    >> I just received a three year old B&S 3.5 horsepower mower from a friend.
    >> Currently, it starts easy but starts pulsing once it's been running for a
    >> few minutes.
    >>
    >> I've been told that the mower ran fine until it was tipped onto it's side
    >> to be cleaned out.
    >>
    >> What I've done so far...
    >> - cleaned the sponge air filter
    >> - drained the gas and filled with new
    >> - sprayed the carb with carb cleaner
    >> - checked oil levels
    >> - ensured that the throttle moves freely
    >>
    >> The only thing that I can think of is that it's internal to the carb, or
    >> that the springs on the carb are not in their correct location.
    >>
    >> Photo's of the carb and linkage.
    >>
    >> http://members.shaw.ca/linkto/temp/carb1.jpg
    >>
    >> http://members.shaw.ca/linkto/temp/carb2.jpg
    >>
    >> Any ideas on how to fix this?

    >
    >
    >The condition is called "hunting", and is caused by a governor that needs
    >adjustment


    I have a rototiller that suffers from that problem -- any link to a site that
    explains how to adjust an air vane governor? I Googled, and found plenty of
    info about adjusting mechanical governors, but didn't find anything about air
    vane governors.
     
    Doug Miller, Aug 9, 2009
    #4
  5. Calab

    RBM Guest

    "Doug Miller" <> wrote in message
    news:h5nj5f$bkl$-september.org...
    > In article <4a7f47f5$0$10302$>, "RBM" <>
    > wrote:
    >>
    >>"Calab" <> wrote in message
    >>news:X9Hfm.90048$...
    >>>
    >>> Howdy!
    >>>
    >>> I just received a three year old B&S 3.5 horsepower mower from a friend.
    >>> Currently, it starts easy but starts pulsing once it's been running for
    >>> a
    >>> few minutes.
    >>>
    >>> I've been told that the mower ran fine until it was tipped onto it's
    >>> side
    >>> to be cleaned out.
    >>>
    >>> What I've done so far...
    >>> - cleaned the sponge air filter
    >>> - drained the gas and filled with new
    >>> - sprayed the carb with carb cleaner
    >>> - checked oil levels
    >>> - ensured that the throttle moves freely
    >>>
    >>> The only thing that I can think of is that it's internal to the carb, or
    >>> that the springs on the carb are not in their correct location.
    >>>
    >>> Photo's of the carb and linkage.
    >>>
    >>> http://members.shaw.ca/linkto/temp/carb1.jpg
    >>>
    >>> http://members.shaw.ca/linkto/temp/carb2.jpg
    >>>
    >>> Any ideas on how to fix this?

    >>
    >>
    >>The condition is called "hunting", and is caused by a governor that needs
    >>adjustment

    >
    > I have a rototiller that suffers from that problem -- any link to a site
    > that
    > explains how to adjust an air vane governor? I Googled, and found plenty
    > of
    > info about adjusting mechanical governors, but didn't find anything about
    > air
    > vane governors.


    The governor is just one possibility for hunting, any number of carburetor
    issues can cause it as well. In the op's case, it appeared that the engine
    was fine until they tipped it over, so my guess is that they inadvertently
    mucked up the vane linkage. I have a pdf I can send you with a typical B&S
    vane adjustment, just email me at
     
    RBM, Aug 10, 2009
    #5
  6. Calab

    Art Todesco Guest

    RBM wrote:
    > "Calab" <> wrote in message
    > news:X9Hfm.90048$...
    >> Howdy!
    >>
    >> I just received a three year old B&S 3.5 horsepower mower from a friend.
    >> Currently, it starts easy but starts pulsing once it's been running for a
    >> few minutes.
    >>
    >> I've been told that the mower ran fine until it was tipped onto it's side
    >> to be cleaned out.
    >>
    >> What I've done so far...
    >> - cleaned the sponge air filter
    >> - drained the gas and filled with new
    >> - sprayed the carb with carb cleaner
    >> - checked oil levels
    >> - ensured that the throttle moves freely
    >>
    >> The only thing that I can think of is that it's internal to the carb, or
    >> that the springs on the carb are not in their correct location.
    >>
    >> Photo's of the carb and linkage.
    >>
    >> http://members.shaw.ca/linkto/temp/carb1.jpg
    >>
    >> http://members.shaw.ca/linkto/temp/carb2.jpg
    >>
    >> Any ideas on how to fix this?

    >
    >
    > The condition is called "hunting", and is caused by a governor that needs
    > adjustment
    >
    >

    Or, it just might need cleaning. On my
    old Toro, it started hunting.
    I found the governor lever caked up with
    mud, grease and grass.
    After a cleaning with a degreaser (spray
    carb cleaner) to remove
    old grease, etc., it ran perfectly.
     
    Art Todesco, Aug 10, 2009
    #6
  7. Calab

    RBM Guest

    "Art Todesco" <> wrote in message
    news:h5nlq5$3pt$...
    > RBM wrote:
    >> "Calab" <> wrote in message
    >> news:X9Hfm.90048$...
    >>> Howdy!
    >>>
    >>> I just received a three year old B&S 3.5 horsepower mower from a friend.
    >>> Currently, it starts easy but starts pulsing once it's been running for
    >>> a few minutes.
    >>>
    >>> I've been told that the mower ran fine until it was tipped onto it's
    >>> side to be cleaned out.
    >>>
    >>> What I've done so far...
    >>> - cleaned the sponge air filter
    >>> - drained the gas and filled with new
    >>> - sprayed the carb with carb cleaner
    >>> - checked oil levels
    >>> - ensured that the throttle moves freely
    >>>
    >>> The only thing that I can think of is that it's internal to the carb, or
    >>> that the springs on the carb are not in their correct location.
    >>>
    >>> Photo's of the carb and linkage.
    >>>
    >>> http://members.shaw.ca/linkto/temp/carb1.jpg
    >>>
    >>> http://members.shaw.ca/linkto/temp/carb2.jpg
    >>>
    >>> Any ideas on how to fix this?

    >>
    >>
    >> The condition is called "hunting", and is caused by a governor that needs
    >> adjustment
    >>
    >>

    > Or, it just might need cleaning. On my old Toro, it started hunting.
    > I found the governor lever caked up with mud, grease and grass.
    > After a cleaning with a degreaser (spray carb cleaner) to remove
    > old grease, etc., it ran perfectly.


    More often than not, that's just the kind of adjustment they need. Damn
    things are very critical, so it doesn't take much to throw them out.
     
    RBM, Aug 10, 2009
    #7
  8. Calab

    dpb Guest

    Calab wrote:
    >
    > Howdy!
    >
    > I just received a three year old B&S 3.5 horsepower mower from a friend.
    > Currently, it starts easy but starts pulsing once it's been running for
    > a few minutes.
    >
    > I've been told that the mower ran fine until it was tipped onto it's
    > side to be cleaned out.


    ....

    One lesser possibility given it's not terribly old but alternative to
    the governor hunting is a variable air leak--loose intake or worn
    throttle shaft are most common of those.

    --
     
    dpb, Aug 10, 2009
    #8
  9. Calab

    JIMMIE Guest

    On Aug 9, 6:16 pm, Oren <O...@127.0.0.1> wrote:
    > On Sun, 9 Aug 2009 15:26:14 -0600, "Calab" <> wrote:
    >
    > >Howdy!

    >
    > >I just received a three year old B&S 3.5 horsepower mower from a friend.
    > >Currently, it starts easy but starts pulsing once it's been running for a
    > >few minutes.

    >
    > >I've been told that the mower ran fine until it was tipped onto it's side to
    > >be cleaned out.

    >
    > >What I've done so far...
    > > - cleaned the sponge air filter
    > > - drained the gas and filled with new
    > > - sprayed the carb with carb cleaner
    > > - checked oil levels
    > > - ensured that the throttle moves freely

    >
    > >The only thing that I can think of is that it's internal to the carb, or
    > >that the springs on the carb are not in their correct location.

    >
    > >Photo's of the carb and linkage.

    >
    > >http://members.shaw.ca/linkto/temp/carb1.jpg

    >
    > >http://members.shaw.ca/linkto/temp/carb2.jpg

    >
    > >Any ideas on how to fix this?

    >
    > Loosen the gas cap a tad and see it runs better. If so the cap vent is
    > clogged. Use a paper clip to clear the cap vent hole.
    >
    > A fouled spark plug might be the culprit.- Hide quoted text -
    >
    > - Show quoted text -


    Im just a tinkerer when it comes to small engines but Ive kept mine
    going over the years. Whenever I have seen this I just go over them
    checking everything. First thought usually is that its a governor
    problem but I dont think I have ever seen that be the problem. Clogged
    fuel path seems to be pretty common and a lot of "I dont knows" it
    just starts working after cleaning everything up.
    I did find one that wouldnt work with cap on. The cap didnt have a
    vent in it so I figured it had to be vented some place else. I had
    taken everything apart and cleaned and put it back together figuring
    this shouldnt be a problem. Well the problem was it had the wrong cap
    on it. I walked down to my brothers house and checked on the back
    porch. There was his gas can with the lawnmowers cap on it.

    Jimmie
     
    JIMMIE, Aug 10, 2009
    #9
  10. Calab

    JIMMIE Guest

    On Aug 9, 5:26 pm, "Calab" <> wrote:
    > Howdy!
    >
    > I just received a three year old B&S 3.5 horsepower mower from a friend.
    > Currently, it starts easy but starts pulsing once it's been running for a
    > few minutes.
    >
    > I've been told that the mower ran fine until it was tipped onto it's sideto
    > be cleaned out.
    >
    > What I've done so far...
    >  - cleaned the sponge air filter
    >  - drained the gas and filled with new
    >  - sprayed the carb with carb cleaner
    >  - checked oil levels
    >  - ensured that the throttle moves freely
    >
    > The only thing that I can think of is that it's internal to the carb, or
    > that the springs on the carb are not in their correct location.
    >
    > Photo's of the carb and linkage.
    >
    > http://members.shaw.ca/linkto/temp/carb1.jpg
    >
    > http://members.shaw.ca/linkto/temp/carb2.jpg
    >
    > Any ideas on how to fix this?


    I took another look and I think the little silver spring is installed
    wrong. I believe it should be attched loosely in the big loop on the
    throtle linkage.

    Jimmie
     
    JIMMIE, Aug 10, 2009
    #10
  11. Calab

    ransley Guest

    On Aug 9, 4:26 pm, "Calab" <> wrote:
    > Howdy!
    >
    > I just received a three year old B&S 3.5 horsepower mower from a friend.
    > Currently, it starts easy but starts pulsing once it's been running for a
    > few minutes.
    >
    > I've been told that the mower ran fine until it was tipped onto it's sideto
    > be cleaned out.
    >
    > What I've done so far...
    >  - cleaned the sponge air filter
    >  - drained the gas and filled with new
    >  - sprayed the carb with carb cleaner
    >  - checked oil levels
    >  - ensured that the throttle moves freely
    >
    > The only thing that I can think of is that it's internal to the carb, or
    > that the springs on the carb are not in their correct location.
    >
    > Photo's of the carb and linkage.
    >
    > http://members.shaw.ca/linkto/temp/carb1.jpg
    >
    > http://members.shaw.ca/linkto/temp/carb2.jpg
    >
    > Any ideas on how to fix this?


    Maybe dirt lodged from tipping in the governor and linkage, easiest is
    try compressed air to blow out everything and see if all moves
    freely.
     
    ransley, Aug 10, 2009
    #11
  12. When I took a small engine repair course, I was told that
    hunting is caused by a governor spring that's stiffened up.

    --
    Christopher A. Young
    Learn more about Jesus
    www.lds.org
    ..


    "RBM" <> wrote in message
    news:4a7f47f5$0$10302$...



    The condition is called "hunting", and is caused by a
    governor that needs
    adjustment
     
    Stormin Mormon, Aug 10, 2009
    #12
  13. Calab

    Art Todesco Guest

    RBM wrote:
    > "Art Todesco" <> wrote in message
    > news:h5nlq5$3pt$...
    >> RBM wrote:
    >>> "Calab" <> wrote in message
    >>> news:X9Hfm.90048$...
    >>>> Howdy!
    >>>>
    >>>> I just received a three year old B&S 3.5 horsepower mower from a friend.
    >>>> Currently, it starts easy but starts pulsing once it's been running for
    >>>> a few minutes.


    >>> The condition is called "hunting", and is caused by a governor that needs
    >>> adjustment
    >>>
    >>>

    >> Or, it just might need cleaning. On my old Toro, it started hunting.
    >> I found the governor lever caked up with mud, grease and grass.
    >> After a cleaning with a degreaser (spray carb cleaner) to remove
    >> old grease, etc., it ran perfectly.

    >
    > More often than not, that's just the kind of adjustment they need. Damn
    > things are very critical, so it doesn't take much to throw them out.
    >

    Critical is right. The shaft only moves
    a few degrees. It doesn't take
    much to make it work poorly.
     
    Art Todesco, Aug 10, 2009
    #13
  14. JIMMIE wrote:
    > On Aug 9, 6:16 pm, Oren <O...@127.0.0.1> wrote:
    >> On Sun, 9 Aug 2009 15:26:14 -0600, "Calab" <> wrote:
    >>
    >>> Howdy!
    >>> I just received a three year old B&S 3.5 horsepower mower from a friend.
    >>> Currently, it starts easy but starts pulsing once it's been running for a
    >>> few minutes.
    >>> I've been told that the mower ran fine until it was tipped onto it's side to
    >>> be cleaned out.
    >>> What I've done so far...
    >>> - cleaned the sponge air filter
    >>> - drained the gas and filled with new
    >>> - sprayed the carb with carb cleaner
    >>> - checked oil levels
    >>> - ensured that the throttle moves freely
    >>> The only thing that I can think of is that it's internal to the carb, or
    >>> that the springs on the carb are not in their correct location.
    >>> Photo's of the carb and linkage.
    >>> http://members.shaw.ca/linkto/temp/carb1.jpg
    >>> http://members.shaw.ca/linkto/temp/carb2.jpg
    >>> Any ideas on how to fix this?

    >> Loosen the gas cap a tad and see it runs better. If so the cap vent is
    >> clogged. Use a paper clip to clear the cap vent hole.
    >>
    >> A fouled spark plug might be the culprit.- Hide quoted text -
    >>
    >> - Show quoted text -

    >
    > Im just a tinkerer when it comes to small engines but Ive kept mine
    > going over the years. Whenever I have seen this I just go over them
    > checking everything. First thought usually is that its a governor
    > problem but I dont think I have ever seen that be the problem. Clogged
    > fuel path seems to be pretty common and a lot of "I dont knows" it
    > just starts working after cleaning everything up.
    > I did find one that wouldnt work with cap on. The cap didnt have a
    > vent in it so I figured it had to be vented some place else. I had
    > taken everything apart and cleaned and put it back together figuring
    > this shouldnt be a problem. Well the problem was it had the wrong cap
    > on it. I walked down to my brothers house and checked on the back
    > porch. There was his gas can with the lawnmowers cap on it.
    >
    > Jimmie


    It seems that every time I let someone borrow a gas can,
    it is returned sans cap. It's always the same. "Where's
    the cap?" "Eye-O-no". I think that's one reason Tasers
    were invented.

    TDD
     
    The Daring Dufas, Aug 10, 2009
    #14
  15. On Aug 9, 5:26�pm, "Calab" <> wrote:
    > Howdy!
    >
    > I just received a three year old B&S 3.5 horsepower mower from a friend.
    > Currently, it starts easy but starts pulsing once it's been running for a
    > few minutes.
    >
    > I've been told that the mower ran fine until it was tipped onto it's sideto
    > be cleaned out.
    >
    > What I've done so far...
    > �- cleaned the sponge air filter
    > �- drained the gas and filled with new
    > �- sprayed the carb with carb cleaner
    > �- checked oil levels
    > �- ensured that the throttle moves freely
    >
    > The only thing that I can think of is that it's internal to the carb, or
    > that the springs on the carb are not in their correct location.
    >
    > Photo's of the carb and linkage.
    >
    > http://members.shaw.ca/linkto/temp/carb1.jpg
    >
    > http://members.shaw.ca/linkto/temp/carb2.jpg
    >
    > Any ideas on how to fix this?


    It appears that your linkage has been modified. Go to the B&S website
    and download the PDF file that will show the proper parts. Then
    install the proper parts correctly. The linkage that the arrow is
    pointing to is not the correct part. I am not sure about the springs.

    Hank
     
    Hustlin' Hank, Aug 10, 2009
    #15
  16. Calab

    JP Guest

    On Aug 9, 2:26 pm, "Calab" <> wrote:
    > Howdy!
    >
    > I just received a three year old B&S 3.5 horsepower mower from a friend.
    > Currently, it starts easy but starts pulsing once it's been running for a
    > few minutes.
    >
    > I've been told that the mower ran fine until it was tipped onto it's sideto
    > be cleaned out.
    >
    > What I've done so far...
    >  - cleaned the sponge air filter
    >  - drained the gas and filled with new
    >  - sprayed the carb with carb cleaner
    >  - checked oil levels
    >  - ensured that the throttle moves freely
    >
    > The only thing that I can think of is that it's internal to the carb, or
    > that the springs on the carb are not in their correct location.
    >
    > Photo's of the carb and linkage.
    >
    > http://members.shaw.ca/linkto/temp/carb1.jpg
    >
    > http://members.shaw.ca/linkto/temp/carb2.jpg
    >
    > Any ideas on how to fix this?


    Try replacing or cleaning the muffler,I have this to be the problem a
    lot of the time.
     
    JP, Aug 10, 2009
    #16
  17. Calab

    Calab Guest

    "Calab" <> wrote in message
    news:X9Hfm.90048$...
    >
    > Howdy!
    >
    > I just received a three year old B&S 3.5 horsepower mower from a friend.
    > Currently, it starts easy but starts pulsing once it's been running for a
    > few minutes.


    Lots of good ideas folks! I really appreciate it!
     
    Calab, Aug 10, 2009
    #17
  18. Calab

    Oren Guest

    On Mon, 10 Aug 2009 16:39:19 -0600, "Calab" <> wrote:

    >
    >
    >"Calab" <> wrote in message
    >news:X9Hfm.90048$...
    >>
    >> Howdy!
    >>
    >> I just received a three year old B&S 3.5 horsepower mower from a friend.
    >> Currently, it starts easy but starts pulsing once it's been running for a
    >> few minutes.

    >
    >Lots of good ideas folks! I really appreciate it!
    >


    Telling us how you fix it will be appreciated.
     
    Oren, Aug 11, 2009
    #18
  19. Calab

    Ulysses Guest

    "JIMMIE" <> wrote in message
    news:...
    On Aug 9, 5:26 pm, "Calab" <> wrote:
    > Howdy!
    >
    > I just received a three year old B&S 3.5 horsepower mower from a friend.
    > Currently, it starts easy but starts pulsing once it's been running for a
    > few minutes.
    >
    > I've been told that the mower ran fine until it was tipped onto it's side

    to
    > be cleaned out.
    >
    > What I've done so far...
    > - cleaned the sponge air filter
    > - drained the gas and filled with new
    > - sprayed the carb with carb cleaner
    > - checked oil levels
    > - ensured that the throttle moves freely
    >
    > The only thing that I can think of is that it's internal to the carb, or
    > that the springs on the carb are not in their correct location.
    >
    > Photo's of the carb and linkage.
    >
    > http://members.shaw.ca/linkto/temp/carb1.jpg
    >
    > http://members.shaw.ca/linkto/temp/carb2.jpg
    >
    > Any ideas on how to fix this?


    I took another look and I think the little silver spring is installed
    wrong. I believe it should be attched loosely in the big loop on the
    throtle linkage.

    Jimmie

    If it's what I *think* it is it should have only the slightest tension when
    the engine is stopped. Is it a very weak spring about 2 inches long (or
    so)?
     
    Ulysses, Aug 11, 2009
    #19
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