Husky 450 won't idle

[RVSardou]

Hi, I have a Husky 450 that starts but won't idle. I've set the spark plug, cleaned spark arrester screen, gas filter, and air filter. Don't know what else to do.

Thanks,
Rick

 

[Jags]

If adjusting the carb doesn't fix that, you might be dealing with an air leak. Let's see what the other motor heads have to say...

 

[CentralVAWoodHeat]

How old is the saw and how much use does it see? Does this happen immediately after starting or does it run well for a bit and then fail to idle? Will it run if you engage the throttle?

 

[RVSardou]

My Chainsaw is 4 years old, with moderate usage. It will run on high speed only, but when I let off the throttle, it will stop running.

It will run only when I keep it at high rpm. In other words when I let off the throttle, it dies.

 

[dougand3]

Try turning Idle Screw CW-increase idle. Idle should be where chain barely doesn't spin or occasionally ticks forward.
If no joy...Could be:
Dirty carb - screen has debris/varnish in it. Esp if ethanol fuel sat in it for long periods of time.
Stiff fuel pump diaphragm and metering diaphragm
H-L screws out of adjustment
Fuel line, purge bulb, fuel pickup trouble (less likely)

Fuel delivery system needs examination. I'd start with carb.

 

[CentralVAWoodHeat]

Try turning Idle Screw CW-increase idle. Idle should be where chain barely doesn't spin or occasionally ticks forward.
If no joy...Could be:
Dirty carb - screen has debris/varnish in it. Esp if ethanol fuel sat in it for long periods of time.
Stiff fuel pump diaphragm and metering diaphragm
H-L screws out of adjustment
Fuel line, purge bulb, fuel pickup trouble (less likely)

Fuel delivery system needs examination. I'd start with carb.

Dougand3 pretty much summed up what I would do as well.

 

[JRHAWK9]

First want to get low speed mixture dialed in, then you can adjust idle speed.

 

[maple1]

My bet is dirty carb. Either from gas varnish stuff, or a piece of dirt.

Running some Seafoam in a tank or 2 may or may not help - if not, complete carb disassembly & cleaning is likely required. Or just get a new Ebay carb.

 

[jetsam]

I'd tune the carb before disassembling and replacing stuff. Only takes a few minutes once you defeat whatever limiters Husquavarna uses.

 

[maple1]

If the carb adjustments haven't previously been touched, I would take that as a sign that it isn't a carb adjustment issue - they shouldn't suddenly go out of adjustment enough to where it will die like it sounds like it is. That is usually caused by the sudden introduction of a blockage somewhere.

Did the saw sit for a while, then the problem arose when you tried to go use it again? Or was it regularly being used when the problem appeared?

 

[jetsam]

If the carb adjustments haven't previously been touched, I would take that as a sign that it isn't a carb adjustment issue - they shouldn't suddenly go out of adjustment enough to where it will die like it sounds like it is. That is usually caused by the sudden introduction of a blockage somewhere.

Did the saw sit for a while, then the problem arose when you tried to go use it again? Or was it regularly being used when the problem appeared?

Eh, it drifts over time- parts wear, filters pass less even after you clean them, outside temps change, and even the adjusters vibrate around a little. If adjustment wasn't needed they wouldn't have adjusters on the carb.

 

[maple1]

True, but what I've experienced is a gradual thing, the drifting you mentioned - tuning adjustments for slight performance changes. Like a slight off-idle bog, or reduced/increased idle speed for example. Or not winding out like it should. 100% of the time I have experienced a sudden 'stop running' issue on just the bottom/idle end in a small engine of any kind, with it still doing OK on the high end, it has been dirty carb.

Unless the OP had some gradually deteriorating performance issues before this that we haven't heard about & weren't addressed? If not, my money is still on dirt/crud/varnish in there.