It's a ROPS, and it shuts down quick because the fuel shut off solenoid engages (or disengages). the time varies from a few seconds to several mnutes, maybe even 20-30 minutes. And it is an L3430HST, you're right
My HST 3430 starts and then will shut-off suddenly. I replaced the fuel shut-off solenoid ($175) and that wasn't it. I have eliminated the seat switch so far and I cleaned the fuses. Any ideas or experience with this problem?