Small Engines (Lawn Mowers, etc.): Lawnmower stops after 5 minutes, water in the fuel, fuel flow

Question
Michael, we Have a 5 Hp Griggs & Stratton lawnmower, in the last 3 times my husband tried to use it, the engine will start for about 5 minutes then it will stop, after 30 min it will start again but again it will stop after 5 min, my husband changed the filter, the oil and the spark plugg. But No lack. What do you think is the problem and how can we fix it. Thanks

Answer
Hi Sanaa,

You will need to determine if the problem is a lack of spark or a lack of fuel flow.  Right after it quits, remove the spark plug, reconnect the wire and lay
it against the engine head.  Pull the engine over and watch for spark at the plug's electrode.

If good, then try to start it while squirting fuel or starting fluid into the carb intake.  If it starts and you can keep it running by adding fuel, then the
carb most likely has dirt, debris or gummed fuel inside.   
You will need to remove the carb, disassemble it, clean all the small internal openings and blow it out with compressed air.   Probe each and every hole with a
small wire.   Adding a carb rebuild kit wouldn't hurt either.  

Another possibility if the problem is fuel related: Check the gas cap to make sure it is venting and not causing a vacuum in the tank.  Check for a good fuel flow from the fuel line at the carb inlet.  Also check for water
in the fuel.  

If no spark, either the safety kill switch (If equipped) is out of adjustment or the ignition coil is faulty and in need of replacement.

Let me know how you make out.
Michael