Husqvarna idle screw issue?

[jefferis]

I have been having trouble with my Husqvarna 435 conking out after 10 minutes and I have struggled to get the right fuel mixture. I have set L and H to 1.5 turns counter-clockwise (the manual does not say which way feeds more or less fuel, but I saw this setting suggested in a video). The saw cuts out when it goes to idle. The spark screen looks good, the fuel is new 50-1 out of the ethanol-free cans, the air and fuel filters are clean, the saw only has 6 - 10 hours on it, and I have cleaned the spark plug with an emery cloth. The question/issue I have is that the idle screw has an infinite rotate. I mean it has no fully off or on stopping point. So, I am having trouble just getting to a starting point... Is this normal or does it indicate a broken idler screw? Also, for a basic FYI, for fuel mix L and H, which direction gives is more gas? Clockwise or counter clockwise? My L may be too low. TIA.
Jeff

 

[Bob Hedgecutter]

Pop the top cover off of your saw- observe the idle screw and how it works upon the main throttle body lever, screw it in until it contacts the plate and then a couple of turns more- start from there and adjust slightly to a point where the chain almost rotates- but doesnt.
However, from your post it seems the saw is no longer holding tune and you are trying to tune out a symptom that may not be tunable.
I would like to see the saw pressure and vacuum tested to check for air leaks.

 

[jefferis]

Okay thank you . For clarification... With the chainbrake on, it idles correctly, but when I set the chainbrake off and the idle speed is way too high, Racing in fact. I cannot see where the screw just touches the plate. It looks like the screw is inside the plate in a hole. I need to turn it way counterclockwise?

 

[Bob Hedgecutter]

You sure you are on the idle screw and not the low circuit?
Racing sounds like an air leak.

 

[jefferis]

Yes, I'm sure. It is above the L and H which require a special tool. It could be an air leak. The bulb pump sounds a bit squishy So, if the low circuit is a problem, turn counter clockwise to reduce speed? If idle screw, turn counterclockwise? The manual is NOT clear on which way is which. But the idle screw seems to turn forever...

 

[jefferis]

this is what I mean about screw being embedded to the plate not just touching it

 

[Bob Hedgecutter]

Yes, I'm sure. It is above the L and H which require a special tool. It could be an air leak. The bulb pump sounds a bit squishy So, if the low circuit is a problem, turn counter clockwise to reduce speed? If idle screw, turn counterclockwise? The manual is NOT clear on which way is which. But the idle screw seems to turn forever...

Counter clockwise should reduce idle speed- clockwise increase it- ON THE IDLE SCREW
On the L or low circuit, set where you are at 1.5 turns out from lightly seated- turning counter clockwise will increase the fuel delivered and make that circuit richer- clockwise will lean that circuit out, usually turning clockwise will increase revs until a point it becomes too lean to run, so L is adjusted to achieve highest revs on that circuit, then counterclocked about 1/4 turn, then adjusted for throttle response from L to H, then idle can be adjusted to stop chain engagement and L + H given final fine adjustments.

 

[Bob Hedgecutter]

this is what I mean about screw being embedded to the plate not just touching it

Yes, the threads screw into the main carb body- but this is NOT a jet like the other two- it is just holding the screw threads in place- come back up the screw towards the head and there is a tapered section, then a flange and then the head of the screw?
It is this tapered section that works on the throttle plate to adjust its position and therefore idle speed.

 

[jefferis]

when I turn the idle screw, the entire screw area below the tapered section also turns. That is why I can't see where it is just "touching" the place. Is that the issue? I have turned the L screw all the way to the right and then turned it 1 turn back counterclockwise. Are you saying it gives too much fuel and my revs may be too high? This is harder than computer science or greek I do both ;-0

 

[Bob Hedgecutter]

Might be time to take it to a shop and have them look at it.

No, I'm saying on the L circuit, counterclockwise will increase fuel and make the revs slower and the saw boggy with poor throttle response- clockwise in will increase the revs to a point of highest RMP and in any more will make the saw "stumble" to a point of stalling, so back out to highest RPM and then back out a touch more to be ever so slightly rich.

 

[jefferis]

Okay, 1 more try. I thank for your help and being patient with me. We recently had an ice storm in texas and I lost over 10 trees and 75 have significant damage and downed limbs, large and small. Hadn't used my chainsaw in a year and was working fine (did not keep fuel in the saw). Anyway, I made a mistake on the racing issue. What happened was I had not released the throttle from the choke set manually. So what happens and what started this whole ordeal is that whenever I take it off throttle, it immediately dies. If I keep it running on high speed it stays on, but chokes out when I release the handle. Adjusting L and throttle screw don't seem to make a difference. I've tried 1, 1.5. 2 turns on the L and no difference. This all started about 1 hour after most recent use a few days ago. It cut quite a few, got hot I guess and started stalling out when I released the throttle. Thought it would just be an adjustment, but maybe something more.

 

[Bob Hedgecutter]

Okay, 1 more try. I thank for your help and being patient with me. We recently had an ice storm in texas and I lost over 10 trees and 75 have significant damage and downed limbs, large and small. Hadn't used my chainsaw in a year and was working fine (did not keep fuel in the saw). Anyway, I made a mistake on the racing issue. What happened was I had not released the throttle from the choke set manually. So what happens and what started this whole ordeal is that whenever I take it off throttle, it immediately dies. If I keep it running on high speed it stays on, but chokes out when I release the handle. Adjusting L and throttle screw don't seem to make a difference. I've tried 1, 1.5. 2 turns on the L and no difference. This all started about 1 hour after most recent use a few days ago. It cut quite a few, got hot I guess and started stalling out when I released the throttle. Thought it would just be an adjustment, but maybe something more.

Full disclosure is always a good thing.

Getting hot you say? Pop the muffler off and show us the front face of the piston via the exhaust port.
435 coping with downed trees is not really a good idea unless the down trees are saplings- couple in a dirty powerhead and dull chain- heat cooked.

Honestly, take it to a shop. No offence, but you sound a little out of your depth.

 

[sean donato]

You sure you are on the idle screw and not the low circuit?
Racing sounds like an air leak.

They had issues with the clams shell cases leaking and I think there was an Intake tearing issue while back with the 435. They let you know real quick when one or the other springs a leak.

 

[Bob Hedgecutter]

They had issues with the clams shell cases leaking and I think there was an Intake tearing issue while back with the 435. They let you know real quick when one or the other springs a leak.

My next step was to walk through all the obvious air leak scenarios and what to check, but honestly I feel a muffler off piston check, or shop check will reveal a lot of answers.

 

[sean donato]

Full disclosure is always a good thing.

Getting hot you say? Pop the muffler off and show us the front face of the piston via the exhaust port.
435 coping with downed trees is not really a good idea unless the down trees are saplings- couple in a dirty powerhead and dull chain- heat cooked.

Honestly, take it to a shop. No offence, but you sound a little out of your depth.

This is good advice, they weren't made for prolonged use like that, and had known leak issues. Time to take it to pop thay muffler off and have a look.

 

[thenne1713]

this is what I mean about screw being embedded to the plate not just touching it

If you have SAWDUST/DEBRIS in there BLOCKING throttle from dropping back to idle, explains your fast speed, and the throttle linkage not touching the idle speed SCREW? Always adjust CARB with BRAKE OFF, so you can tell whether clutch engaging/ disengaging properly.

 

[Pioneer]

If it runs at high idle but not at normal idle you may have a blocked idle transfer port. There are three holes in the carb body by the butterfly valve when it normally sits in its position at idle. The purpose of these three holes is to provide fuel flow when at idle and to help transitioning from idle to full throttle. If any of these holes are blocked it could give you the symptoms you describe.
Normally you would take the carb apart and put it in solvent to dissolve any gelled fuel that may be blocking the holes, but you may be able to blow them out with carb cleaner. To do this you take the idle mixture screw out and put the nozzle of the carb cleaner in the idle mixture screw hole and flush out the circuit. If you see spray coming out of all three holes you know the passages are clear.
If you want to do this you will have to remove the limiter on the idle mixture screw if it's still in place. Either way you will probably have to take the carb off to do this.

Draining the fuel from the tank and running the carb dry does not guarantee all the fuel will be removed from the carb. I've had small engine carburetors plug up even after I do this, it takes very little fuel to plug up the small ports in a carburetor after the fuel sits in there for months and gels up.

 

[coffeebrk]

@jefferis, what is the overall condition of saw? Approximately how many hours of use? I'm wondering if you could have worn clutch springs. Idling fine with brake on then racing idle when off, hmm...

 

[thenne1713]

<<Draining the fuel from the tank and running the carb dry does not guarantee all the fuel will be removed from the carb. I've had small engine carburetors plug up even after I do this, it takes very little fuel to plug up the small ports in a carburetor after the fuel sits in there for months and gels up.>> THIS is the reason that many shops now recommend to use canned fuel and run a few minutes before putting into storage.

 

[rupedoggy]

Pioneer, did you read the part where he said it takes a special tool to adjust the jet screws?