Small Engines (Lawn Mowers, etc.): Riding lawnmower engine problem, craftsman lawn tractor, safety switches

Question
QUESTION: Dear Eric,

I am trying to use an old Craftsman 42 inch 17 HP turbo cooled riding lawnmower (model no. 917270722) to do my mother-in law's yard. Unfortunately, after starting the engine as soon as I load the engine , either by engaging the clutch (even with the gearshift in neutral) or by engaging the cutting blades, the engine stalls out.

I know that there is a problem with the electric starter switch (possible short) but could this also cause the engine to stall under load? Or is there an engine a timing problem? Does the flywheel connect to the crankshaft via a key like on my push mower? It is possible that our nephew run the mower over some very uneven ground.

Than you in advance for your help, Sincerely,   Mike

ANSWER: There is a flywheel key just like your push mower.  However, larger engines rarely shear flywheel keys.

Do you have to keep the clutch pushed in to keep the engine running?  Does the engine die instantly when you release the clutch even with the tranmission in neutral?

Is this your manual?

http://www.managemylife.com/mmh/owner_manuals/16811/CRAFTSMAN-Lawn,-Tractor-9810





---------- FOLLOW-UP ----------

QUESTION: Eric,
Yes, I have to keep the clutch in to keep the engine running. Even with the transmission in neutral the engine dies instantly when the clutch is released.

This does appear to be the manual for this lawnmower. Thank you for sending it as I had been looking on line for one. My mother-in-law could not find the original.


Thanks again for any help you can give me.  Mike

Answer
Take a look at the wiring diagram...sounds like something with one of the safety switches is causing a problem.  

Find each of the safety switches and test them.  The safety switches are simple open/close (on/off) style switches just like a basic house light switch.  A simlpe multimeter with a continunity test function is a quick way to see if the switches are working.

Often times I found that just dis-connecting and re-connecting the harness plugs fixes the problem;  most likely reason is there is some minor corrosion causing the issue.

Let me if there is anything else I can do.

Eric