[exitatwill]

I was cutting grass/bagging leaves when 20HP Walker MC#90951 shut down. ~250 hours on machine. Engine runs fine, machine will move in reverse. Machine shuts down with any forward motion, or when blades are fully engaged. I have checked continuity of 3 safety switches that I know of; #7 Safety Switch (seat), #16 PTO Safety Switch, #18 Safety Switch. Any ideas how to fix this problem?

 

[intrigue12]

That for sure is a switch problem. There has to be more than just three switches. Check them all and clean them up. Let me know after you have made certain that all your switches are good and all your fuses are ok.

 

[ericg]

It could be an issue with the time delay circuit. In order for the machine to start the pto must be off and the forward speed control in neutral. Those safety switches have to be good since the mower starts. When the machine is running, if the operator gets off of the seat with either the forward speed control moved or the pto engaged, the time delay module kicks in and the relay will ground the coils after 1.5 seconds shutting down the engine. They put the module in the circuit to prevent nuisance shut downs if the operator was bounced off of the seat after going over a bump.
Since you said that the engine dies with either pto engagement or forward movement, it would seem like a time delay issue or the wiring associated with the time delay circuit.

see page 11 for a description of the operator presence circuit
http://www.walkermowers.com/manuals/mowers/model-mc-manuals/6000-13_pub.pdf

see page 56 for the wiring diagram
http://www.walkermowers.com/manuals/mowers/model-mc-manuals/6000-12_pub.pdf