Have 18 in 42 cc Craftsmen chainsaw ran great then started having start and run issues Replaced carb with new one replaced all fuel lines, spark plug,bulb. Checked muffler ,carb gaskets, started hard then ran great then shutoff though all was good next day hard to start would not run again took new carb apart thinking dirt in fuel mix but still not running looked at piston and rings look good ?
Running out of things to check any help would be great Chris

 

Did you look at the piston and rings through the exhaust port? If they are indeed good, then check for crankcase leaks or a loose cylinder/jug.

 

Even if the piston looked ok, there may be scoring on the cylinder. Might want to give it a once over.

 

Will tear apart again and look at both Thanks will get back

 

How's the ignition strength?

 

it has good spark 80 on compresssion lots of fuel when I pull plug and turn over. When I press on blub it remains in? after pull on throttle and choke it releases push again same thing happens remains compressed. Any help will help. will take whole thing apart an look.

 

Sounds like you still have a carb problem, or lines reversed.

 

2 fuel lines 1 has fuel filter smaller line goes to small line on carb closer to fuel valve other larger line from carb to bulb then to return in fuel tank? Am stumped New carb and also took apart to see. Every thing looks good. Thanks for replies