I have a craftsman gt 6000 with kohler 18 hp magnum today it started fine and ran goodd for over an hour i put gas in it and ti would not stay runing it stated surging and popping and cuts off

Are you asking for leak down pressure, bmep, or compression ratio? Depending on the hours on any L-head engine the carbon deposits will create higher pressure. Running the engine while spraying water as from a Windex bottle will clean them out.

Check your fuel cap vent. What is repair man finding?

key switch or safety switch on the clutch/brake pedal

to be honest the enigne ahas a control that the left side must fire and run before the right starts to fire it sounds to me like you have a fuel issue possibly the carb. is gummed up and dirty.

The carb. needs to be cleaned. Pay extra attention to the high speed circuit.

I'm going to throw this quick one at you but there are several problems that can stop the spark reaching the plug. Check the connection at the seat switch. The "connector" has a built in switch in addition to the switch that it plugs into. This is designed to prevent people from unplugging the connector and installing a jumper wire to bypass the seat switch. If this is not making proper connection it will kill the spark. You may also check the pluger switch for the seat as well. Hope this gets you in the right direction.

First check fuel shutoff valve on bottom of carb . Disconnect and remove , clean witn carb cleaner and be sure there is power at wire when the key is on . Also clean carb jets and bowl .....

The noise is likely coming from the starter solenoid which is the heavy duty relay that sends battery power to the starter motor. If this is the case clean the wire connections going from the battery, to the solenoid and to the starter and try it again.

carb float sticking open dumping gas into cylinders

youve got a short in the wireing ,prob right at the clutch peddle switch