Craftsman Riding Mower Won't Start after I stalled it

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  #1  
Old 07-04-09, 04:01 PM
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Craftsman Riding Mower Won't Start after I stalled it

I recently got a Craftsman riding mower (917.256530 with B+S engine 28N707-017301) from a family member. It hadn't run in a couple years but i was told it had been running fine except for a starter gear problem. I replaced the worn ring gear under the flywheel and starter gear, and starter solenoid(thanks to some posts found here). I also put in a new battery. I was able to get it up an running, let it idle for 10-15 minutes at which time it seemed to respond well to raising and lowering the throttle. I then tried to get it moving by letting the brake/clutch out while the motion controller on the hydrostatic transmission was in one of the forward positions (I now think this is the incorrect way to use a hydro drive?) which stalled the engine. After that i haven't been able to get it going again.

The electric starter motor engages and the flywheel turns. When i release the ignition the engine will continue (at the same slow speed the starter got it going to) for 5-10 more cycles then stops.

I've tried emptying out the old gas from the tank and carburetor bowl and replacing with fresh gas. I've also taken off the carb and tried cleaning it out with a spray carb cleaner. The main jet (or main nozzle?) is definitely not clogged but i'm not sure how to check the idle opening. I've also replaced the sparkplug with a new one (though the old plug passed a quick check to see if it sparked while i held it in my hand still connected and grounded to a bolt while turning the engine over). The gas is definitely getting to the carburetor, there's no clog in the fuel line (it fills the carb bowl every time i remove the fuel line, empty the bowl, and replace the fuel line). Also, if i take the air filter off and turn the ignition i can see some gas spraying out of the intake.

Some more info:
1) When i remove the spark plug it's covered in gas and oil. 2) When i was testing the spark plug i noticed gas spraying out of hte spark plug hole (which makes me think i'm getting gas to the cylinder just fine).
3) The exhaust gets hot while i'm trying to get the engine going (does this mean the spark is igniting the fuel in the cylinder?).
4) My brother suggested that since there's a strong smell of gas afterwards maybe the fuel/air mixture is too rich going to the engine, so i tried tightening the idle screw on the carb a but this didn't change anything (so i put it back).

I don't have any experience working on engines (until now), but i'm not adverse to trying and tinkering. I would LOVE to save $$ by fixing this myself too. Plus, now that i've spent a few days i don't want to let it beat me.

Any thoughts on how to get this mower going?
 
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  #2  
Old 07-04-09, 06:42 PM
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It sounds like the engine is flooding which can be caused by a couple of things.

The first is the choke isn't pulling off like it should.

The second would be the float valve is leaking and the float can't shut off the fuel flow to the carburetor. That problem could either be caused by the float valve or the float.

Try starting over. Pull the spark plug, shut off the fuel to the carburetor and spin the engine over about ten times with the throttle on full open.

Then replace the plug and see if it will start with the throttle half open and the choke off.
 
  #3  
Old 07-04-09, 10:33 PM
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Check the flywheel key. My bet is that it is sheared either because the flywheel bolt wasn't torqued tight enough, or there is grease/oil on the crankshaft between the flywheel and crank.
 
  #4  
Old 07-05-09, 04:48 PM
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The flywheel key was sheared. Is there a drawback to overtightening the flywheel bolt? I don't have a torque wrench to adjust it to 95-105 ft/lb (source: "Large Air Cooled Engines 1989-2000" Vol. 2, 2nd Ed., Intertec Publishing) so i didn't crank down on the bolt too hard. Is it OK to just get it as tight as I can with a couple of monkey wrenches?
 
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Old 07-05-09, 08:37 PM
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95-105 ft lbs is pretty darn tight. Wrench down on it and you should be fine.
 
  #6  
Old 07-06-09, 07:12 AM
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95 ft. lbs is a lot of torque. You do need to hold the flywheel from turning, then push with both hands putting all your body weight into it.
If you don't get it tight enough, you will continue to shear the keys. And do NOT put oil. grease or never sieze on the shaft. Shaft to flywheel needs to be a dry fit to help hold it in place.
 
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Old 07-06-09, 05:50 PM
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Can you not rent or borrow a torque wrench??? ,, As Indypower says the worst you can do is shear another key, but it would be kinda nice to know it's tight & not need to worry about it anymore,,,,,, Roger
 
  #8  
Old 07-09-09, 05:10 AM
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Finally got the replacement part

I finally got the flywheel key, installed it and the lawnmower runs fine now. I bought two in case i sheared the first replacement (they're pretty cheap, i probably spend more on gas getting one). I really cranked down on the flywheel bolt this time, if i shear this one i'll look into borrowing/buying a torque wrench.

Thanks for all the help.
 
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