Hi, this is Peter

I have a Craftman lawn mover won't start. I found out that is the intake valve stuck close
I took of the intake and cleaned it. It fire up but then after 3 minutes it shut off and stuck again. I try to clean the valve and valve guide up to 3 times and it done same thing over again. Please adsive me what could be wrong?

Thank You

If the intake valve was sticking open, then cleaning the guid or checking for a broken valve spring might work. Since it is stuck closed, you must have a bad lobe on the cam, because that is what opens the valve.

I had open the gear box and verify the cam, it was find.

The valve got stuck by something's yellowist deposited (coking) on stem valve, I have to use a hammer to removed it. Is there possibility that oil may leaking by the seal and coked up when it under heat? Or is it the valve warping?

It has to be stuck "open" impossible to be stuck closed and run at times. Use a carbcleaner and clean like crazy, probably will have to remove and clean well. It is due to pooooor gas on the market today.

Don