Can't get mower restarted

Discussion in 'Mechanic and Repair' started by Odyssey, Nov 13, 2006.

  1. Odyssey

    Odyssey LawnSite Member
    from Texas
    Posts: 12

    I have a 6.5 hp Sears mower (large rear, small front tires-don't know model number, but trust not essential?), about 3 years old, which has given me very good service, including starting (most of the time) on the first crank. Air filter is cleaned, spark plug and oil changed regularly, etc.

    About a month ago, I wanted to mow, but the mower uncharacteristically just did not want to start. Finally, I primed it several times and it burst into life. I did my mowing, but when I released the dead-man bar, it died as it is supposed to, but unusually with a considerable burst of smoke (dark colour). I tried to restart it without any success until I again primed it several times (maybe a dozen) and it started with a cloud of smoke but immediately died. Could not repeat the start.

    Changed the old plug for a new one, removed the carb and checked/cleaned the float chamber. re-assembled with high hopes, but no cigar.

    Finally changed the air filter and the gasoline and it started again. Dirty gasoline maybe?

    Have used the mower once since getting it running again (it ran normally), and today is second. It started and ran normally, but when I shut it off to move to a different place, the dark cloud came from the exhaust again and now it simply will not start. I have to believe that the dark cloud is the key to the problem, but have no idea what might be causing it (oil level in within markings and I was mowing level ground.)

    Since I got all new gasoline a month ago, I do not expect that it is now a dirty fuel issue although anything is possible. However I am adding Stabil to the fuel at the recommended amount and wonder if this could have anything to do with this problem?

    If not, what should I be looking for? Thanks.

    P.S. If I remove the fuel from the mower tank, what could I use to filter the fuel to see if there is any water in it (would like to rule this out)?
     
  2. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    you really need to post the make and model #'s of the engine itself.
    You said you tried to start it a month ago. When was the last time it ran good before that?
    Sounds like to me you need to pull and drain the tank. Blow out the carb. Fresh fuel and filter if equiped.
     
  3. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Posts: 2,231

    Like Khouse said engine numbers would help but most likely you have a Tecumseh engine as this was common for Craftsman. If everything else is normal as you indicate and it is a Tecumseh, I would double check the bowl nut(main jet) for any obstructions. There are 3 ports in most bowl nuts, two opposed at the bottom and one in the side just above the threaded area which will require a tag wire to clean thoroughly. In addition most of the later carbs on the Tecumseh engines have a plastic emulsion tube(usually pink or green) which is sealed on both ends with small orings and they tend to deteriorate. You can remove the emulsion tube from the carb by using the flat end of a small screwdriver to reach into the throat of the carb and push it out of the bottom of the carb. If the orings look good you likely have other issues. Part number on the oring is 632547. When the oring(s) go bad this allows the engine to overfuel which could account for the smoke when shutting down. Is the smoke black or blue? Normally blue smoke is oil related and black smoke is fuel related. If it is not a Tecumseh then you're on your own until you come up with some engine numbers.

    Dutch
     
  4. Odyssey

    Odyssey LawnSite Member
    from Texas
    Posts: 12

    Thank you both. The engine is a 6.25 hp (apologies, not a 6.5) Briggs & Stratton.

    Could not find a model number for the engine, but did find model number of mower which is 917-379070. For what it is worth, found a diagram at http://www3.sears.com/
    (enter model number in search box,
    "continue" on next screen
    "view diagram" for "ENGINE/HOUSING/HANDLE" and "continue" again for diagram.)

    It ran fine up until one month ago, when I had the situation that I described. I used it once since then, no problem. Used it today and all normal until I released the dead man lever, then the dark (blackish) smoke, just like one month ago. Cannot start it now.

    I would suspect the gasoline too except, as stated above, it is fresh (well, one month old, but with Stabil). Probably it is the carburetor, but is this something that a guy with two left hands can manage to clean?
     
  5. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,022

    If you look on the metal plate right above the muffler you will most likely find the model numbers stamped in it.
     
  6. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    did you install the correct spark plug? is the gap correct? have you checked the spark - is it hot and blue? next time it does that pull the plug and dry the end with a lighter then stick it back in and try it.
     
  7. Odyssey

    Odyssey LawnSite Member
    from Texas
    Posts: 12

    Have been through the B&S site extensively, but still cannot find what I am sure is the engine model #. The only thing that I could find is

    FAMILY: YBSXS.1901 VC
    274469

    but the search function on the B&S site doesn't know about those numbers.

    Have bought a starter spray which I shot into the intake valve and it started right up then immediately died (3 times) in a cloud of dark smoke (don't know if this is from the starter spray or part of the problem?). FWIW, the primer is working OK as I can see gasoline squirting into the intake when it is pressed.

    The plug tip (gap of which is correctly set) was somewhat wet when removed (after the above exercise). So we know:

    it has a spark
    fuel is getting as far as the priming mechanism
    it will not start without the starter spray

    What does this tell you? Thanks in advance.
     
  8. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,022


    Tells me that the main jet which may be in the center of the float bowl nut may have trash in it.

    It's hard to diagnose without being able to see what you have there.

    Look on the plate as below and see what you find.

    Briggs 625 Blower Hsng..jpg
     
  9. Odyssey

    Odyssey LawnSite Member
    from Texas
    Posts: 12

    The information on the plate where you indicated is the info that I earlier provided:

    FAMILY: YBSXS.1901 VC
    274469

    I also found a serial number on the opposite of the engine:

    120802-0252-B1 02111957 (the 3rd character might be a "Q" instead of a 0)

    but neither # has lead me to any further info.

    Am going to have a go at cleaning the carb, but from my previous experience, want to go about this as efficiently as possible. When I previously removed the fuel line at the carb, of course I had no way to control the fuel flow which I tried best I could to divert it into a large plastic bottle.

    Do any of the more seasoned or imaginative members have any tips on how to cut off and to control the emptying of the fuel tank without my creating another ecological disaster? TIA
     
  10. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Posts: 2,231

    In the absence of a fuel line clamp, use a pair of visegrips to put a moderate amount of pressure on the fuel line then pull the fuel line off the carb. At this point the bowl nut(main jet) can be removed and cleaned. If this doesn't solve the problem, I would remove the carb by removing the two cap screws that retain it. When the carb is removed it will be necessary to disconnect the governor linkage from the throttle shaft. If you wish to rebuild the carb and completely clean it, the rebuild kit is most likely #498260. The rebuild kit contains extra parts that fit other walbro carbs so don't think that all parts will be used. For that carb the parts used will be bowl gasket, bowl nut gasket, needle and seat and replacement oring seal on the crossover tube. Make sure all gum and varnish is cleaned from the carb bowl. Go after it.

    Dutch
     

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