Small Engines (Lawn Mowers, etc.): Excel power washer, spark plug wire, valve clearances

Question
Hi Eric,

I could really use your help Eric.
I have a Excel model 2002 CWT
2-gpm, 2000psi. power washer
It has a Tecumseh model #OHH50 engine
It's approximately 16-years old and purchased new.

I have used this most every year since purchase and it has always performed perfectly till now.

It starts and runs perfectly but it won't turn off.  I even removed the spark plug wire and it continues to run at what appears to be idle or just above. The only way I can turn it off is to ground the plug to the frame to kill the motor.

I suspect that somehow the timing was advanced causing it to run very hot causing ignition even without the plug wire.  At least that is the only thing I can think of that could cause this.

Any ideas?  If it is the timing just how do you set the timing on this engine?


I'm using it in Colorado at an elevation of 7500ft, however it has worked well at sea level as well as 8000ft so I don't think this is an issue.  I only mention this because nothing has happened to this engine and yet it is now acting as if the timing advanced causing it to run very hot.

Any help you can give me Eric would be very appreciated.
Thanks,
JD in Ft.Collins, Colorado

Answer
I would start by checking the valve clearances.  
Both valves:  .004"

http://www.smallenginesuppliers.com/html/engine-specs/tecumseh/Tecumseh_quick_re

Engine service manual:

http://www.smallenginesuppliers.com/html/engine-specs/tecumseh/Tecumseh_4-Cycle_

Valves or a sheared flywheel key could cause the timing you mentioned.  I would check both.

The repair manual links should help.
Eric