Interesting MS460 problem; see if you can guess what it was

[madhatte]

One of the work fleet crapped out a couple weeks ago while we were doing storm cleanup, and I didn't get around to fixing it until today. All I knew from my co-worker was "It didn't wanna stay running so I grabbed another".

So, symptom elaboration time.

Popped on three pulls. Flipped the switch up, and it started on the next pull. Ran about 20 seconds then slowed down about 500 rpm, then quit. Wouldn't start again. Inspection showed wet fuel around the exhaust port, and a wet plug. Fuel was 92 octane mixed 50/50 with Stihl HP Ultra. Saw has maybe 500 hours on it. Pulled exhaust cover; horizontal machine marks on piston are clean and sharp, and rings are fine. Carb smells of fuel. Spark tested good: fat blue spark. Saw was running until it wasn't.

I'll give you guys 'til I get home from work and I'll post the solution.

 

[Fifelaker]

You wrote 50/5o not 50:1 What do I win?

 

[Trx250r180]

fuel line softend ,colapsing after starts up ?

 

[madhatte]

You wrote 50/5o not 50:1 What do I win?

D'OH! Typo. You win the satisfaction of not being oblivious.

 

[slangegger]

Saw was running until it wasn't.

I often find the same thing.

 

[Andyshine77]

Dirty air filter.

 

[Stihlasaurus]

Flux capacitor on sideways?

 

[atvguns]

too much fuel or not enough air could the choke be stuck or air fillter clogged ?

 

[Dan_IN_MN]

You wrote 50/5o not 50:1 What do I win?

Plugged spark arrestor.

Yep....with that much oil the screen would plug!































(I know it's a typo.....fwiw...)

 

[zogger]

mud daubers in the muffler..

..that's always my stock guess...sometimes I am right...

 

[MS260 Fan]

Out of gas?

Out of gas? I guess if it was you would have heard it lean out before it stalled...

 

[sgrizz]

soft fuel line, clogged fuel filter.

 

[3000 FPS]

I will try one that has not been mentioned yet. The High adjustment vibrated loose.

 

[struggle]

I will try one that has not been mentioned yet. The High adjustment vibrated loose.

A guy brought over to me a Huskie 281 to replace a recoil on and adjust it and both the low and high screws were out all the way like that:confused2:

Very strange very strange but it must happen, owner said he did not adjust anything so they must have worked out.

For the 460 I say it stayed choked hence it flooding even though you flipped it off.

 

[jbighump]

debris in needle valve wouldnt closeso it floods the saw

 

[rob066]

Debris in fuel metering needle.

 

[rob066]

debris in needle valve wouldnt closeso it floods the saw

You beat me to it

 

[RAMROD48]

Water in the tank?

 

[lone wolf]

Water in the tank?

Naw he put the oil in the gas tank!

 

[madhatte]

The two details that are the best clues are the "cleaning up storm damage" and "ran until it didn't". Turns out, a branch snaked into the space between the engine and the tank-handle and pulled the impulse line off the nipple. I never would have guessed that one until I found it, so that's why I put it up here.