Chainsaw hard to start after warmed up
- Thread starter Hipastore
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Need to be a bit more specific with what saw. Depending on the saw there are different tricks to get then to fire up.
Just wanna talk about this question. My saw looks good.
Since you don't really want specific help, the obvious answer is let it sit and cool off.
Let's try this a different way...is your saw a "carbed" saw or an MTronic ? Could it be vaporlocking ? Flooding?
Certain models have certain idiosyncrasies...hence the question "what saw are we talkin bout ?"
Certain models have certain idiosyncrasies...hence the question "what saw are we talkin bout ?"
sand sock
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my old stihl 361 has 1 fuel line . i just flip the red to run and it starts on the first pull if its hot, occasionally i flip it to half start, if it sat a tad longer.
my husky 562 has maybe 4 different fuel lines and the purge bulb. cold start, everything is normal. if the saw is hot. adn i shut it off for a few seconds , just pull in run position and it goes. if i wait maybe 1 to 2 minutes. i have to pump the purge a few times and pull it 1 time and its starts. i am pretty sure the heat from the saw, pushes the fuel away from the line . making a air pocket. but it is a new saw and i am still learning
my husky 562 has maybe 4 different fuel lines and the purge bulb. cold start, everything is normal. if the saw is hot. adn i shut it off for a few seconds , just pull in run position and it goes. if i wait maybe 1 to 2 minutes. i have to pump the purge a few times and pull it 1 time and its starts. i am pretty sure the heat from the saw, pushes the fuel away from the line . making a air pocket. but it is a new saw and i am still learning
A couple of reasons a saw can be hard to start hot. None of them have to do with their being M-Tronic or Autotunes as an ignition/carb system. All have to do with the physical properties of the saw and sometimes the age of the components. One of the biggest miss interpretations spread online. Heat soaking a saw usually has to do with the saws basic design and ability to shed heat. Especially when hot. I had a 1980's Husqvarna 154 vapor lock this weekend. Put it in the shade for a few and it restarted first pull. Back in those days a lot had to do with the carb mounting & screws transmitting heat from the Cylinder back to the carb. All brands with that style of mounting had similar issues in hot climates. One of the reasons for the rubber "boot" better isolating the carb from the cylinder with essentially a non heat conducting connection. The new saws with the "layback" cylinders crowd the airbox in their attempt to be lighter and more compact along with the transfer ports running along side the exhaust to get heat, a thermodynamic equation at play to make saw designs more efficient. Results in a saw design that hold heat more than some of the earlier designs. Hence a greater propensity to vapor lock. The "major" players have further developed these designs over the last 10 years to solve that with changes to the partition materials between the cylinder & air box, improving air flow to cool better, design the muffler & relation to the cases to also rid heat better so the later designs shed heat better therefore have less vapor lock issues.. ( For example early prior to 2016 Husky 562's were more prone. Later ones had updates which helped from fuel line placement to altered covers. The NEW 562's have had many changes from cases to covers to make it no more likely than any saw design to vapor lock.. Then the NEWER designs like 572 and 592 addressed those issues much better )
The heat soak/vapor lock issues is not new. I remember Homelites boiling the gas!
So the saw mechanical DESIGN is really the biggest reason, The OTHER "main" reason a saw will be hard to start hot is compression, They get a little long of tooth and the wear gets to the point the compression drops.... one of the first "signs" is a hard to restart saw. Last as ignition components get older and their internal properties get less resistant to heat, that can also make a saw hard to start. Be it condensers on an old points ignition to the internal materials separating the windings on later CDI's And can't leave out the fuels/gasoline used, some simply go to vapor easier.
The heat soak/vapor lock issues is not new. I remember Homelites boiling the gas!
So the saw mechanical DESIGN is really the biggest reason, The OTHER "main" reason a saw will be hard to start hot is compression, They get a little long of tooth and the wear gets to the point the compression drops.... one of the first "signs" is a hard to restart saw. Last as ignition components get older and their internal properties get less resistant to heat, that can also make a saw hard to start. Be it condensers on an old points ignition to the internal materials separating the windings on later CDI's And can't leave out the fuels/gasoline used, some simply go to vapor easier.
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Most here, peeps with 100s of saws, just buy a new saw. Time is money, seconds count, sub-seconds count. GET a new saw!!!
Sometimes it is an unrealistic expectation on the part of the owner who thinks the saw should start first pull with the throttle closed to the idle position. 2-stroke engines basically do not like to start with a closed throttle so most newer saws have a feature where the throttle is automatically opened when the full choke setting is engaged for cold starting. If a saw won't start when hot with a closed throttle, it can sometimes be remedied by adjusting the idle speed screw and the L screw to achieve a more open throttle at idle with the idle set just below the speed where the chain moves, however, it is difficult to get this setting on some saws and the carb has to be set to the fast idle/no choke setting to get it to start quickly. That's why the fast idle position is provided. If the saw doesn't have vapor lock or some other non-start issue and it won't start after 2 or 3 pulls when hot with the throttle closed, you have to open the throttle or you will be pulling for a long time.
This happen to you or you just seeking general knowledge?
Interesting the OP is HIPA , Another reason for hard start saws is the RPM's needed to get a spark from the ignition. Being a parts supplier, a way to differential might be address that with ignition replacement parts and possibly better heat resistant materials in the fuel and pulse lines. Lines that maintain their shape better. Husqvarna did address the ignition side of this with the 372 X-torq's early on. They altered the ignition on the later ones to deliver spark with less RPM's , that made it easier to both start and restart 
Maybe " accessory " kits for saws like the early 550's/562's & other "eco" designed saw with a cover to improve air flow, a heat shield for the partition and even a muffler designed for the older ones to reduce heat build up in those saws. Guess it depends on the volume of saws sold that could use a bit of help. Folk buy all kinds of bling for their saws to make them louder and look flashy, maybe things that actually improve the saws useful life might sell too.
Maybe " accessory " kits for saws like the early 550's/562's & other "eco" designed saw with a cover to improve air flow, a heat shield for the partition and even a muffler designed for the older ones to reduce heat build up in those saws. Guess it depends on the volume of saws sold that could use a bit of help. Folk buy all kinds of bling for their saws to make them louder and look flashy, maybe things that actually improve the saws useful life might sell too.
He has stated no specific reason for asking the question other then to ask the question. Seems some people have lots of time on their hands to generically answer said question. I don't, so I asked if it was for a specific saw. He said no, it was just to ask a question. So I gave the most pertinent response in my opinion. No need to get another saw, simply let it cool off.
Throw it at a tree, a log or hit it with bigger hammer.
Remember you didn't ask for good advice
Yep. But I do not wanna send my saw to the shop when this happens to it.
MS 250
Just wanna seek general knowledge. Cus I do not wanna send it to shop when this happens to my stihl ms 250.
HIPA means high quality parts.Interesting the OP is HIPA , Another reason for hard start saws is the RPM's needed to get a spark from the ignition. Being a parts supplier, a way to differential might be address that with ignition replacement parts and possibly better heat resistant materials in the fuel and pulse lines. Lines that maintain their shape better. Husqvarna did address the ignition side of this with the 372 X-torq's early on. They altered the ignition on the later ones to deliver spark with less RPM's , that made it easier to both start and restart
Maybe " accessory " kits for saws like the early 550's/562's & other "eco" designed saw with a cover to improve air flow, a heat shield for the partition and even a muffler designed for the older ones to reduce heat build up in those saws. Guess it depends on the volume of saws sold that could use a bit of help. Folk buy all kinds of bling for their saws to make them louder and look flashy, maybe things that actually improve the saws useful life might sell too.
Valuable advice! So I need to check the ignition system of my saw. Thanks.
LOL. Good advice.
I like his advice. So easy to solve this problem. I just wanna seek general knowledge about this. Thanks. LOL
I am going to buy a new saw when it happens. LOL . Just wanna seek general knowledge about this problem.Throw it at a tree, a log or hit it with bigger hammer.
Remember you didn't ask for good advice
