I have a lawn mower that dies about 5 seconds after It's started, I've removed the carb and cleaned the ports, I've also tested the coil and spark plug with a spark plug tester in between the coil and the spark plug, There was a spark

So I checked the oil and filter, The filter was fine but the oil was filled way past the mark so I decided to remove the spark plug, turns out it was black, so I changed it and it ran fine for about 30 minutes, then it died again.

I removed the spark plug again and it has a light brown oily residue on the edges of the plug, but not on the electrode, any Idea's why it keeps dying ? could the piston rings be shot from someone over filling the oil

  • Not sure what to say here. You've exercised (to us) the idea that you've done this before. If that is the case, then how is "someone overfilling it?" What you didn't say, and should correct if you didn't correct it, is DRAIN the oil, and keep it at the right level. Fire clean the plug. Also, ensure the tank has NO deposits in it, ensure the fuel line is clear, filter if it has one (for FUEL) is clear and that the gas cap breathes properly. And in the future, do the easy things first. (cleaning a carb can be tricky, and if goofed, a nightmare to sort out if inexperienced) – noybman Jul 8 '19 at 4:17
  • Has “someone” used a 2-stroke mix for the fuel? After removing the ports on the carb, did you reset them correctly? – Solar Mike Jul 8 '19 at 4:44
  • @SolarMike I drained the fuel and reset them correctly, at noybman the oil was drained and refilled to the correct level, the fuel line is way short and clear of any obstructions and the push mower filter has been cleaned, as I said I just replaced the spark plug and set it to .30 instead of cleaning it up... it just drives me wild that it would only run for 5 seconds, then after replacing the spark plug, it only ran for 30 minutes – hello moto Jul 8 '19 at 5:21
  • Is the plug wet (with fuel) after it runs? It could be that the check valve in the carb is faulty, flooding the cylinder. – stevieb Jul 8 '19 at 23:53
  • Its generally simply, air, fuel, or spark. What you describe leads us to believe spark is "ok" but you can clean all the connections up. With air, you'd suffocate fast enough that it wouldn'b be running for 30m. So it sounds like fuel first, spark second. You mentioned a dirty plug that was oily. So sure the piston rings might be tired but I usually like to ensure fuel is good - you ran for 30m, it probably is. Is this fresh gas? Presume since you drained it that it is, but if its from what was laying around, it could be bad gas still. – noybman Jul 9 '19 at 2:04

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