Saw fires but won't start

[Josh_H]

I have a ms440 that has good compression (just put a new piston in it), spark, just put a new fuel line in it etc.
After I let it sit for a while, it will start briefly on full choke then die, after that when I pull it over, it just fires and jerks my hand back. Any thoughts would be appreciated.
Thanks
Josh

 

[rupedoggy]

It's too lean

 

[Canyon Angler]

Not getting fuel.
I would check everything from the fuel filter downstream.
Did the carb work before you replaced the piston?

 

[Josh_H]

The fuel line is brand new and the filter is not plugged up. I cleaned out the carb but I don't what kind of internal shape it's in, the saw was sitting for a while before I replaced the piston.

 

[U&A]

Fuel, air, spark



Sent while firmly grasping my redline lubed RAM [emoji231]

 

[rupedoggy]

Did you ever ask yourself, "why did it have a bad piston to begin with"?

 

[Canyon Angler]

I cleaned out the carb but I don't what kind of internal shape it's in

 

[Yotaismygame]

After it fires once start squirting fuel down the throat and see if it keeps running. That will determine if it’s fuel related. Otherwise could be a coil or a whole bag of other things

 

[Wood Doctor]

My friend's 390 did the same thing. I found a crack in the fuel line and replaced it. That worked, but you said you replaced the fuel line. So, I think the carb is the next crook in the line up. Carbs for a 440 are so cheap these days that I usually replace both the fuel line and the carb.

 

[lsc86]

Seen cracks in the carb to intake boot and/or gasket (depending on exact setup you are working on). Big enough to let in air leaks and cause it to die out, but too small to see with naked eye until replaced.

 

[Yotaismygame]

I've had coils go bad to where it was firing at the wrong time and thus would only fire one time per pull.