Ms390 stops abruptly

[Robert Raven]

Hi there,

 

All of a sudden my ms390 has a problem. It starts ok, revs up nicely for maybe 10 seconds, then stops dead. Restarts again immediately with no problem, then does the same thing again. Checked filters and plug, didn't get any further than that. Would like to look into it further tomorrow, any ideas where I should start?

 

Thanks,

 

Rob

[WorcsWuss]

Sounds like fuel starvation, I'm working through a similar problem on saw.

Is this 10 seconds of open throttle....?

Will it run for longer on part throttle...?

If so that suggests insufficient fuel getting into the cylinder for high revs.

Could be fuel hose, could be a weak pump diaphragm, dirt in the carb....

I'm down to fuel hose & pickup..... if replacing those still doesn't sort mine then I'm stumped!

[Stubby]

Tank breather blocked ? try it with the fuel cap open ( on its side ) .

[treemonkey4]

If it starts up immedietly after, I personally don't think it's fuel. I would start with a new spark plug as it's cheap if not that I would look at coil.

[spudulike]

Tank breather blocked ? try it with the fuel cap open ( on its side ) .

 

Took the words right out of my mouth - good advice and a good quick way to check for this fault:thumbup:

 

Someone has been listening to me, gold star....top of the class:lol:

[jjll]

I had a similar problem with a stihl hedge cutter, found a very small split in a fuel hose which probably didnt help,sorted that but still doing the same, it turned out to be the diaphams,had them changed and runs as it should now.