Craftsman Lawn Mower not starting.

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  #1  
Old 07-13-09, 06:07 PM
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Craftsman Lawn Mower not starting.

Hello,
I bought a Craftsman Lawn mower (mower specs below) that the previous owner cannot start. He told me that he was mowing and hit a stump then the thing sputtered and died. Of course thinking that this must be the flywheel key, I bought it ($25). While removing the engine shrouds, I noticed that a mouse ate the insulation off the SAM wires. I checked for spark and nothing. A new SAM was installed, and I was able to get spark, but still no fire. I removed the flywheel and the key was ok. I checked the carb, the fuel solenoid is clicking when the key is turned to run. I sprayed starting fluid directly into the carb, still no fire. I removed the bottom of the carb thinking that there might be crud, but everything looked ok.
For fun, I removed the valve cover and the valves are moving when the motor is turning over. I did notice that the exhaust valve has a little clearance between the rocker and the valve stem. The intake is tight. There is no adjustment on the valves. I would need to remove them and grind down the stem.
I am at my wits end. The Kohler service manual states to remove the white (kill) wire from the machine harness to eliminate the kill circuit. Doing this killed the spark. I even tried to take the red wire from the SAM and directly connect it to the positive terminal of the solenoid - still nothing. Any Ideas?

Craftsman 16.5HP Mower
Model No 917.271141
Kohler CV16S Spec 43527

Thanks - Mudder409
 
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  #2  
Old 07-13-09, 11:54 PM
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Does it have compression? Does it have a solenoid on the bottom of the carb?

The valve clearances are not adjustable and there is no need to adjust them. The lifters are hydraulic and self adjusting.
 
  #3  
Old 07-14-09, 03:21 AM
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According to the service manual, this engine has a compression release cam. Its very hard to find the compression. When I try to check, it is somewhere around 50psi.

It does have a soleniod on the bottom of the carb. It does click when the ignition is turned on. I removed it from the carb and it does move when grounded to the motor.
 
  #4  
Old 07-14-09, 10:38 PM
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Try putting a spoonfull of gas into the spark plug hole and see if it will start for a moment. If so, you have fuel problems.
 
  #5  
Old 07-19-09, 08:50 AM
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I put some gas into the cylinder. No luck. Still no fire. I was thinking about trying to start the engine out of the tractor. If I do, I would need to supply the 12v to the red wire on the SAM. The ground would be to the block and I could hit the starter with the battery positive. Do you know what the white wire to the SAM would be? I think its kill to ground.
Does this seem like it would work? If I am having trouble with any of the switches or safety relays, this should by-pass them. I know that this is not the best/safest thing to do, but I feel I am running out of options.
 
  #6  
Old 07-19-09, 09:55 AM
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I wouldn't go to the trouble of taking it out of the tractor. If you're getting good spark (bright blue) and can't get it to start with fuel in the plug hole you either have a mechanical problem in the compression or ignition timing area.

The only thing that affects ignition timing is the position of the flywheel on the crank = if the key is OK and the flywheel slot is on the key that's all there is to it.

If you have problems with getting a spark at the plug and you want to eliminate all safety switches from the circuit, I would go straight to the ignition module on the flywheel and disconnect the kill wire. Keep in mind you will have to choke a running engine to kill it without the kill wire.
 
  #7  
Old 07-22-09, 06:38 PM
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New Developments:
I removed the rockers from the valves. Then I pressurized the cylinder. The exhaust valve leaked air consistantly. Is this pointing to a bent valve or is this part of the compression release mechanism? Any thoughts?
 
  #8  
Old 07-23-09, 12:55 AM
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That's a valve problem. The compression release is disabled with the rocker arms off.
 
  #9  
Old 07-29-09, 07:29 PM
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I removed the head. The exhaust valve seat was out of position. It looks like it was run this way for a while. I hammered the seat back in with a piece of wood as a buffer, and installed everything back on. With a couple of cranks the thing was running. Who knows how long the seat will stay pressed back where it belongs is anyones guess, but at least it is running.

Thanks for the help.
 
  #10  
Old 07-29-09, 10:03 PM
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You can peen the seat back in place to keep it from coming out again, but you already put it back together. When it comes back out, you can do this to permanently fix it.
 
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