Husqvarna 240 still won’t start!

[Guvnah]

Thanks in advance to anyone who might be able to lean me in the right direction. I was given this saw by a friend who couldn’t get it running after it quit one day. It had rope wrapped around the chain crank. It had terrible compression.

I have replaced the piston and ring. I also resealed the cylinder and did a leak down test and pressure test. It now has 165 PSI compression. I switched out the carb/Gaskets and spark plug. It has new mixed gas. It is getting spark. Sometimes it pops off but never starts. There is no rational reason it won’t start. Any ideas?

 

[irhunter]

Does it always pop after you pour a bit of mixed-gas down the plug hole?

Did you switch to an AM or OEM carb?

New fuel line?

Does this saw have an impulse line, or nipple, or what?

Roy

 

[lone wolf]

Flywheel key sheered!

 

[Wood Doctor]

Flywheel key sheered!

You beat me to that same conclusion. I ran into this ten years ago with a Stihl Farm Boss. I replaced the flywheel and tightened the nut with a 12" pipe extension on a socket wench to make sure it was up to specs. That fixed it.

The key is simply an alignment part and contributes almost nothing to the joint strength.

 

[Guvnah]

Does it always pop after you pour a bit of mixed-gas down the plug hole?

Did you switch to an AM or OEM carb?

New fuel line?

Does this saw have an impulse line, or nipple, or what?

Roy

AM carb. I replaced the fuel lines. No impulse line. Seems have a direct hole to hole from the crank to the carb.

 

[lone wolf]

You beat me to that same conclusion. I ran into this ten years ago with a Stihl FarmBoss. I replaced the flywheel and tightened the nut with a 12" pipe extension on a socket wench to make sure it was up to specs. That fixed it.

The key is simply and alignment part and contributes almost nothing to the joint strength.

I just put a flywheel on a saw last week with no key lined it up as best I could, advanced the timing same amount as another saw like it and it runs fine.

 

[irhunter]

I agree with guys above...checking flywheel key is free and easy.

There should be a rubber-like impluse nipple.

https://www.amazon.com/Impulse-Hose-505310751-Replacement-Husqvarna/dp/B0CJ82HZ9J

I have had mostly good luck with AM carbs...but, others report a somewhat high out-of-box failure rate.

Roy

 

[Guvnah]

I just put a flywheel on a saw last week with no key lined it up as best I could, advanced the timing same amount as another saw like it and it runs fine.

I will check the flywheel but I don’t remember it being stripped or chipped.

 

[Bob Hedgecutter]

I will check the flywheel but I don’t remember it being stripped or chipped.

Check to see if it is loose- but really it needs to come off to see if the key is still intact and the flywheel has not shifted around the crank to throw the timing all to heck.

Also, if it is not flooding- have a look to see if the fuel line is kinked under the air box- where it exits the tank and enters the air box.

 

[Northerner]

Every time I get a 240/235 in shop I really have to work with myself to not just tell the customer right away to just go throw it in the dumpster…

However, I have to agree with the others, check flywheel. It happens. Seen it numerous times on chainsaws and trimmers already.