MS 250 starting issue

[BC WetCoast]

I was assigned a MS 250 to use as a ground saw and it has an issue I don't understand and neither can the other foremen in the shop.

When the saw is cold it starts fine, fires within a couple of pulls.
When the saw is hot, ie running for a while and then shut it off for a short time, to say refill it, it will restart fine.

However, if you run it till it gets hot, then shut it down for a while, say 1/2 - 1 hour, so it is still a little warm, it won't restart.

The saw is about 18 months old, but like any production saw that is interchanged amongst crew, is not cared for in the best way. We operate in a wet climate, but the problem exists both when the weather is wet or dry. All the other equipment (saws, blower, hedgers) operate fine, so it isn't a fuel quality issue.

Thanks for your help.

 

[50blues]

Gas tank vent? When it starts to cool down is it sucking a vacuum in the tank?

 

[stihl for life]

Gas tank vent? When it starts to cool down is it sucking a vacuum in the tank?

i second that maybe tank vent it plugged

 

[machinisttx]

If it was the tank vent, wouldn't it also have an issue with starving for fuel when running?

 

[BC WetCoast]

Thanks for the reply, I'll check the tank vent tomorrow.

 

[naturelover]

Doesn't sound like this is the problem, but a simple and cheap check nonetheless.

Is it firing when it won't start?


Sent from my iPhone 5 using Tapatalk

 

[Saw Dr.]

Rather than speculate, the easiest thing to do is slap an inline spark tester on it when it wont start. If it has spark, then you're most likely up against a fuel delivery issue. I find many folks hesitate to use the choke more than once a day. If it wont fire after 6 or 7 pulls, choke it and try again. The jetting is set very lean on these, and it may just not be getting any fuel.

It is not uncommon for the older 1123 saws to need crank seals, but I have yet to see a 250 needing them unless damaged bby leaving brake on. Fuel lines are also known to crack on those.

 

[Wood Doctor]

Cracked fuel lines have been a problem on the 025 and the MS250, so I have to second Saw Dr.'s point. The crack usually shows up as a hairline crack right above the fuel tank or at the connection point with the carb.

 

[BC WetCoast]

Thanks for your replys

 

[watsonr]

I'm with the Doc... does it have spark... probably needs a coil.