Chainsaw Gremlin

Charles in Aus.

Well-known Member
Every now and then I have a Gremlin that mucks about with my chainsaws .
It happens with all four of the smaller ones , the larger Sthil hasn't been affected .
Saws cut and run well idle normally at set speed , have normal power and start easily , but at idle, intermittently and without warning run fast , so fast the chain runs and threatens to injure something or someone .
Use it a little more and sometimes it goes away , sometimes not .
Restart the saw from cold , no Gremlin for a few uses , then up he pops again .
Really annoying ! I know the idle speeds are set correctly because for 99% of the time the saws behave perfectly and yet this problem just keeps happening .
Any ideas or suggestions please ?
 

When you set the saw down, or are just letting it idle---set the

chain brake, if it has one. Some older models don't have a chain brake.
 
Charles,I could be trash or varnish in the carb idle circuit,causing it to run lean thus the increase in RPMs.
 
Sounds like you have an air leak somewhere causing a lean condition. Check the carb boot closely for cracks. You could have crankshaft seals going bad. The base gasket could be leaking as could the cylinder to base gasket. I would take those saws to a dealer and have leak down test performed on them. Lean running saws are a seized ring and scored piston just waiting to happen. Don't forget to closely examine the fuel line for leaks, too. Running well when cold and running lean when hot is a classic symptom of bad crank seals. Hope that helps you out.
 
Sounds like a fuel problem. Maybe getting old, wrong oil mix, contaminated, something. I'd dump what's in the saws and replace with fresh mix. Also check that the fuel lines haven't cracked or are working loose.
 
watch out for one of these guys
notorious for tampering with anything mechanical

they don't like lighted areas so look in dark corners and under objects
never get them wet or you'll have even more problems
feeding them after midnight brings even dire behaviour

good luck
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Dump your gas from the tank into something clear and let it sit for 5 minutes. See if it looks like water in the bottom of the container.

It sounds like you are getting ethanol 'phase separation'. The ethanol may be absorbing enough water from the atmosphere and separating from the gasoline When a 2 cycle runs on pure ethanol the speed is uncontrollable and its not getting any oil either because the oil won't stay in the ethanol. It only mixes with the gasoline.
 


Thanks , some good leads to follow up on . Cantankerous female chainsaws :D :D
I will admit the Jerry can I use for two stroke fuel is getting on but it is a really handy size and solid as well . Any tips on things to filter fuel through ?
 
I had a saw doing the exact thing you mentioned and found the fuel line was cracked inside the fuel tank.
 
If your chainsaw is running right and idle is set correct you should be able to set brake and let it idle.
 

Classic sign of an air leak. Check fuel lines, intake block gasket/boot, crank seals, crankcase halves and make sure the head is on tight.
 

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