12.5 won't start?

Discussion in 'Mechanic and Repair' started by Shady Brook, Dec 26, 2001.

  1. Shady Brook

    Shady Brook LawnSite Bronze Member
    from Indiana
    Messages: 1,517

    I just replaced the sump seal on my 12.5 kaw. put her all back together on my scag 36, and now she won't start. It is blowing some stinky stuff, and smoke out the muffler on some of the pulls. I have pulled this thing about 200 times, and nothing. I think turning the engine over, may have caused a gas oil mixture. I had this happen on a Toro once. She would not start, and the engine acted siezed up. Same thing on the scag, so I pulled the motor a second time, checked things out, and put back on. On first instalation, I could not pull the chord, acted siezed. Second time, I could pull laboringly. Now after a couple hundred pulls, she pulls pretty normal, but still no start. Help me please.:confused: :)

    Oh, also, I pulled the spark plug, and it had a oil residue on it, so I cleaned it up, and replaced, still nothing. Let her set a few hours, tried again, same story, no start.

    Thanks in advance
  2. vipermanz

    vipermanz LawnSite Bronze Member
    Messages: 1,773

    sounds like the pulling problem could be a sheared flywheel key
  3. Robert Doubrava

    Robert Doubrava LawnSite Senior Member
    Messages: 342

    If the plug had oil on it, could it possibly be an internal problem?
  4. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    Hmm... I'm going to assume that while you had the base (sump cover) off of the engine that you did not mess with the camshaft.

    You need to eliminate causes of starting problems in order to find out why it won't start.

    I would start with making sure it has a good, clean supply of fuel. Change the fuel filter. Remove the float bowl from the carb and clean it out. While you have the float bowl off make sure the float isn't stuck. It should move up and down freely.

    Next remove the spark plug and throw it away. Get a new plug and gap it properly. With the new plug make sure you are getting a good spark.

    Now while the plug is out of the engine pull the engine over about 10 to 15 times. This should clear any oil or other nasty stuff that is in the induction system and combustion chamber. Put the new plug in the engine.

    Change the oil and filter.

    Disconnect the engine wiring from the mower. By doing this you are eliminating any wiring problems the mower may have developed while you were moving the engine around like pinched wires and/or disconnected safeties.

    Put the choke on and give the engine a few pulls. It should start. If it does start kill the engine by turning on the choke again. Reconnect the wiring and try to start the engine again. If it won't start then you have a wiring problem.

    If you have eliminated everything I mentioned above and it still won't start then come back and tell me and I'll tell you how to do a rudimentary camshaft timing check.
  5. Dave

    Dave LawnSite Senior Member
    from RI
    Messages: 315

    Richard i s correct I amsume this motor was turn up side down ,filling everything with oil even the carb,It sounds like its trying to ignite oil and thats what the smell and smoke is,pull the plug and do what Richard said,also you might want to spray some carb cleaner in to the cylinder and carbto dilute the oil,pull it ten times or so them put a new plug in it
  6. Shady Brook

    Shady Brook LawnSite Bronze Member
    from Indiana
    Messages: 1,517

    Thanks for all the suggestions men! Still no go.

    Oil defineately got into the carb, and into the air filter and such. I pulled the carb off, hosed it with cleaner, and filled the carb up with sea foam to help clean it up. I sprayed carb cleaner in the cylinder, and just about anywhere that I could shoot it. :D New plug went in, pulled 250,000 times give or take 10. No start, sore shoulder, bad disposition. I used starting fluid, some extra noise, almost seemed like she wanted to kick over a couple times, but still not go. Help!

  7. Fish

    Fish LawnSite Member
    Messages: 139

    Did you have the sump off? If so, what else did you happen to
    move, pull out, look at, etc..? What about the wiring to the
    coil? Try pull starting it with the wire disconnected. Go through
    everything you did from the start. If it ran fine before you
    worked on it, then something is not right and the solution is
  8. Shady Brook

    Shady Brook LawnSite Bronze Member
    from Indiana
    Messages: 1,517

    The coil is fine, I did a spark test, and there is a spark. Even after cleaning the carb, after several pulls, I am seeing a oily residue in the carb again. Maybe I have not cleaned the carb throughly enough. I really did not touch anything else. I separated the motor to get to the sump gaskett, and replaced another seal. Really did not handle the internals of the motor. I gave some mighty pulls with some seafoam in the carb, and she acted like she wanted to start, but once that seafoam departs, she does not seem like she is inclined to turn over. I can get almost the same effect with the starting fluid, but it takes a big pull, and only lasts for a couple pulls before fading. I think it must have to do with the oil getting into the carb. Not sure how to cure it, unless I go get some varnish and soak it. Seems like it should start with just a little oil in there. She has been a hard starter for a while now, and I can not figure that out either. Float looks fine, but in any event, something is wrong.

  9. 65hoss

    65hoss LawnSite Fanatic
    Messages: 6,360

    Check all your OPC switches. You may have one bad. Make sure the blade engagement linkage is not slightly engaged. The Trans is in neutral, if its slightly off it will not start.

    Pull the dipstick and see if gas is in the crankcase.
  10. Shady Brook

    Shady Brook LawnSite Bronze Member
    from Indiana
    Messages: 1,517

    ok, I am about to loose my mind.

    I have done everything I can think of to get this beast started, but no go.

    I have changed carbs, and she still will not start. The carb is not the problem. I think I must have oil in the combustion chamber. Any thoughts on how to clean that thing out? I am really frustrated after fooling with this thing for several days. Wasted!


Share This Page