Primer bulb - then engine dies (Stihl FS40)

RnR

Joined
Dec 16, 2005
Messages
563
Location
Michigan, Thumb's Up!
Just to avoid confusion... I'm not flacoman (who also had difficulty with primer bulb failures)- but still had to recently replace my FS40 primer bulb due to cracking. The engine seemed to run just dandy up to this point. However, now the darn engine won't seem to run for more than 5 seconds or so without sprutterin' and dying. Does this symptom clue any of you guys in to what my underlying problem might be?
 
Joined
Dec 28, 2003
Messages
501
Location
Manitowoc, Wisconsin
 Originally Posted By: RnR
Just to avoid confusion... I'm not flacoman (who also had difficulty with primer bulb failures)- but still had to recently replace my FS40 primer bulb due to cracking. The engine seemed to run just dandy up to this point. However, now the darn engine won't seem to run for more than 5 seconds or so without sprutterin' and dying. Does this symptom clue any of you guys in to what my underlying problem might be?
Sounds like a cracked fuel line assembly. Just replaced one in my FS55.
 
Joined
Dec 26, 2006
Messages
409
Location
Tampa, Florida
Though I have experience with Stihl products none have been FS40s. Nonetheless, here are suggestions. Typically, there is a plastic pick up at the end of the fuel line in the tank that has a filter screen. I have never seen one totally stopped up but it's possible. More likely, there is something in the carb. I'd suggest removing it. There are covers on opposite sides of the carb each held on by 4 little screws. Under one cover is a tiny inlet needle with a spring and under the other cover is an open chamber. I normally take off the covers very carefully, so as not to damage the gaskets, and then spray out all the passageways using a can of carb cleaner with the straw attached. I bet that will fix it.
 
Joined
Feb 21, 2004
Messages
2,149
Location
USA
 Originally Posted By: RnR
Just to avoid confusion... I'm not flacoman (who also had difficulty with primer bulb failures)- but still had to recently replace my FS40 primer bulb due to cracking. The engine seemed to run just dandy up to this point. However, now the darn engine won't seem to run for more than 5 seconds or so without sprutterin' and dying. Does this symptom clue any of you guys in to what my underlying problem might be?
How do you handle your fuel mixture. Do you leave it in the tank and how long of a period. Stale gas can do harm to rubber parts and gaskets.
 

RnR

Thread starter
Joined
Dec 16, 2005
Messages
563
Location
Michigan, Thumb's Up!
I have done very little maintenance to this FS40 over the years I've had it, although the fuel pickup has been replaced and perhaps that needs to be done once again. I may also need to take the carb apart and flush that out too. The fuel has never been drained, just run dry and put up for the winter.
 
Top