Small Engines (Lawn Mowers, etc.): Hard starting and quits running after 5 seconds, rubber gaskets, carburetion problems

Question
I have a Ryobi RY60511 2-cycle cultivator which is very hard to start(at least 10 pulls). Once started the engine will run for up to 5 seconds then most times begin reving up as if giving it throttle then instantly dies.  Other times it runs for about 3-7 seconds and dies.  It will not stay running for more than 7 seconds at all. I have now taken apart the carborator cleaned(was not dirty inside), replaced all parts using a carb rebuild kit and put it back together and still does the same thing over and over. Spark plug still fine and gapped correctly (has VERY slight black oil residue on the electrode). Gas/Oil mix is 2.6oz to 1Gal as stated in the manual. Has new fuel, fuel filter, fuel lines and bulb. The engine has only been use 2-3 hours from new. There are no carb adj screws that I have seen. Whats next? Any suggestions appreciated.

Answer
Hi Russel,

I am of two minds about your problem(s) here.  But before I start with my troubleshooting advice,

I am hoping that when you cleaned the carb., you were careful about the kind of carb cleaner that was used.

This is because some carb cleaners are harmful to the rubber gaskets and such within the carb and you have to be very careful not to damage them.

Anyhow, when you tried to start the machine (it appears) that you found the spark was slightly dampened with a light coating of oil.

Therefore you must rule out:

Defective Spark,

Restricted Air Filter

Improper or Stale Fuel

Sheared or Partially Sheared Flywheel

Carburetion Problems having to do with flooding or Priming

Ignition system.

You can test the engine compression using a compression tester.  Low compression a DRY spark Plug normal fuel flow, a fully functioning carburetor indicates an internal engine problem.

Wet spark shows the fuel is being supplied adequately by the carb.  Engine sometimes flood from a restricted air filter.  faulty spark plug, too much priming or or choking,  improper settings or defective carburetor, and/or the wrong engine timing.  You can use a shop towel over the spark plug hole and once you turn the engine over 4-5 times removes the excess gas from the engine cylinder.

Give'em a try, - let me know.

Regards,
Howard
The ignition system relates to your coil possibly not functioning properly.