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Stihl 460 Chainsaw problem

Started by oregonsawer, February 24, 2009, 03:55:22 PM

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oregonsawer

I have a 460 stihl chainsaw that runs really great when  cold
and after just a fue cuts it will die when you put the power to it.

It does this every time, when you pull the throtle on it acks like it is starving
for gas.

Do any of you chainsaw guys know what could be the problem?

Oregonsawer


Rocky_J

It's probably running too lean for whatever reason. It might just be a carb adjustment (or cleaning/ kit). Or it might be a leaky crank seal.

Once again I'll post up the carb adjustment page.  ;)
http://www.madsens1.com/saw%20carb%20tune.htm


There are other possible causes as well, it could be a plugged fuel filter or a bad fuel line or any of a half dozen other oddball possibilities. But most of the time it's the carb.

Rocky_J

And just to add a sense of urgency to your problem, please be aware that running the saw lean for any extended period of time WILL result in seizing the motor. The fuel also carries the engine lubrication, so running it lean means not enough oil on the bearings or rings. It will grind to a halt one day if you do not get the lean condition fixed.

I'm in the middle of replacing a piston and cylinder on a MS460 right now for a landscaper buddy. He did the same thing, ran it lean and then was all surprised when it seized up on him one day. I'm waiting on a $200+ parts order from Bailey's and then he still has to pay my labor to rebuild the saw. The dealer told him it was junk and just buy a new one. I told the guy a year ago to adjust the carb on his 460 because it was screaming too high/ running too lean. But he didn't want to mess with the carb adjustment limiter caps because he was afraid he'd 'void the warranty' or something. Well, he burned it up and didn't get any warranty either.

Troutfisher

Check for a cracked fuel line, the carb will suck in air through the break in the line and starve the saw for fuel.

L. Willey

Sometimes when an old fuel line warms up it will get more limber, and collapse and not let fuel through.

chevytaHOE5674

Quote from: L. Willey on February 24, 2009, 09:19:59 PM
Sometimes when an old fuel line warms up it will get more limber, and collapse and not let fuel through.

X2. I would start with replacing the fuel line, both in the tank and out of the tank. Also toss an impulse hose on it.

joe_indi

A partially blocked pickup body or strainer would cause this problem.

Quote from: Rocky_J on February 24, 2009, 08:00:19 PM
And just to add a sense of urgency to your problem, please be aware that running the saw lean for any extended period of time WILL result in seizing the motor. The fuel also carries the engine lubrication, so running it lean means not enough oil on the bearings or rings. It will grind to a halt one day if you do not get the lean condition fixed.

Very true .
I see this happening here nearly every day.
Another symptom is that when the fuel supply is restricted due to a partial blockage, when the saw is just out of a cut, it has a high idle speed for some time, more like its running out of fuel.


Al_Smith

 It's running lean for whatever reason .

First try richening up the high speed jet just a tad bit and see if that helps . If not check the fuel filter ,line etc .

In rare cases tiny little wood fibers find there way into the carb by magic or something and plug the internal screen .How they get passed the main filter is anybodies guess but it does happen .

Of course a stiff carb diaphragm can cause a lean out under power .They might seem to run just fine out of the wood but falter in the cut .Kits are cheap and a rebuild is so easy even I can do it . :)


Ed

Quote from: Al_Smith on February 25, 2009, 05:45:43 AM

Of course a stiff carb diaphragm can cause a lean out under power .They might seem to run just fine out of the wood but falter in the cut .Kits are cheap and a rebuild is so easy even I can do it . :)



Yup! The diaphram kit is only 5 bucks & real easy to install. If Al can do it anyone can.  :D

Ed



oregonsawer

Think you guys for the info.
I will try what you suggest.

I use this saw alot as I have a portable sawmill.
A-LT70 Woodmizer.
Thank you again, This is a great web site!!!!!!!!

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