Qualcast Punch 35S,cuts out after a few mins.running?

I was kidding myself hoping that clearing all the oily grass had cured the frequent cut-outs.I used the Punch 35S today(15/6/09) and it was back to it's old tricks again.I noticed a regular drip of petrol from the float chamber so I cleaned the seal and reassembled it-leak fixed.However I still think Cledlyn's suspicion of the cut -out lead(Throttle control end) is the most likely culprit.I finished the last 20 mins. of mowing without a cut-out but if the problem returns the whole cut-out mechanism is in for a thorough sevice.

Terry Taylor- original question asker.
June 2009

I had the same problem. Removing the petrol tank cap as soon as it starts stuttering cures mine - I assume that it's not sucking in air to replace the fuel as it burns thus creating a vacuum that eventually stops the fuel flow.

Peter B
June 2009

Thanks for the advice Cledlyn.I removed the engine cowling and flywheel to check LT and HT leads.TheWipac unit seems fine as was the lead insulation.What was evident though was the large amounts of oily grass around the motor,explaining my overheating problems.With the debris removed I ran the engine for 15 to 20 mins.with no cut-outs,it even ticks-over slowly and smoothly.Maybe the overheating was causing regular vapour locks to the fuel induction.

Terry.
June 2009

check that the wire to the stop switch/contact doesn't have any breaks or vibration worn areas. If the cable arcs to earth it will stop the engine. Also check the clearance at the engine stop contacts-are they within arcing distance is anything loose that will allow the contacts to touch.
It is unlikely to be a sticking valve-you would hear the engine note change and the engine would not run smoothly.
If it starts and runs first time when cold then you have a very good engine look for the less obvious

cledlyn
June 2009