Poulan 18" 40CC chainsaw stalls under load - HobbyTalk
 
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post #1 of 13 (permalink) Old 12-30-2007, 09:38 PM Thread Starter
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Poulan 18" 40CC chainsaw stalls under load

Got it new. Unit worked fine for the first hour or so, then began stalling under load (i.e. as I applied the chain to a tree it'd bog and die). I removed the bar and chain today and it'll go like hell w.those removed, w.only the flywheel/sprocket spinning, but when I reattach the bar/chain - even very loosely - it bogs.

There's no other apparent problem - fuel lines ok (not split), nothing else overtly going on. I wouldn't think it's a carb issue since it happened so soon after first use, but what do I know?! Don't think it's an air leak either - the 4 bolts underside are tight and secure. The brake is not on and works properly.

Any ideas why it's bogging and dying? Again, it only does this under load.

thanks!
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post #2 of 13 (permalink) Old 12-30-2007, 09:58 PM
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Sounds like it's running too lean, could be a carburetor adjustment, or it could be an air leak. If it's one of the new "strato charged" designs they are set to run very lean from the factory and it could just be that since it's had some run time it needs a little adjustment.

If this saw is new, I would suggest taking it in to a warranty repair facility and let them check it out for you.
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post #3 of 13 (permalink) Old 12-31-2007, 12:56 AM Thread Starter
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Originally Posted by 30yearTech
Sounds like it's running too lean, could be a carburetor adjustment, or it could be an air leak. If it's one of the new "strato charged" designs they are set to run very lean from the factory and it could just be that since it's had some run time it needs a little adjustment.

If this saw is new, I would suggest taking it in to a warranty repair facility and let them check it out for you.
I got it at Sam's new, but out of the box. It was unused but I shoulda known. Tried to save a few more bucks They wouldn't take it back as such and by the time I motivated and tried to get it warranteed it must've been out of warranty so I was SOL. Cost of inspection at a repair shop will be at least an hour and I'm already at least half way to the cost of new. Anyway, it's gotta be 3 yrs old by now (maybe 4?) so I don't know about the strato bit.

I'll try to monkey w.the carbs, make some adjustments.

As for air leak how would I know for sure, besides taking it to a shop for them to test? Is it something I can do at home? I do all my motorcycle work so at least I know how to turn a wrench.
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post #4 of 13 (permalink) Old 12-31-2007, 01:05 AM
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Do you know the specific model number of your saw?

Some models of Poulan chain saws have fuel pump pulse hoses that can cause air leaks and or rubber intake manifolds that can leak as well. You should also inspect the fuel fuel filter and fuel lines to make sure there are no leaks and that the fuel filter is attached to the pickup line. A 3 year old chainsaw can have carburetor issues even if it has only been used less then an hour, once fuel has come in contact with the components inside the carburetor, there can be problems with diaphragms, and metering circuits, needles & seats etc...
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post #5 of 13 (permalink) Old 12-31-2007, 01:13 AM Thread Starter
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Originally Posted by 30yearTech
Do you know the specific model number of your saw?

...A 3 year old chainsaw can have carburetor issues even if it has only been used less then an hour, once fuel has come in contact with the components inside the carburetor, there can be problems with diaphragms, and metering circuits, needles & seats etc...
SM4018. The problem began pretty much when it was new so it's def not an age-related issue, though age (old fuel, aged bits, etc) is exacerbating the problem and maybe causing more.
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post #6 of 13 (permalink) Old 12-31-2007, 10:32 AM
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After looking at a breakdown of your saw, the only place I can see where there may be an air leak would be the insulator between the cylinder and carburetor. Check to make sure this is tight and you should be alright.

I think that if you open up the load adjustment or high speed adjustment about 1/4 turn (counter clockwise), it may take care of your problem. Since it appears to be running good with no load, opening up this adjustment should give it the extra fuel it needs for a load. The high speed or load adjusting screw is marked with an "H" and is the one located closest to the back or air intake area of the carburetor.

Best of Luck...

Last edited by 30yearTech; 12-31-2007 at 10:33 AM.
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post #7 of 13 (permalink) Old 12-31-2007, 11:56 AM Thread Starter
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Originally Posted by 30yearTech
Check to make sure this is tight and you should be alright.

I think that if you open up the load adjustment or high speed adjustment about 1/4 turn (counter clockwise), it may take care of your problem.
Best of Luck...
Thanks for your help. I'll do as you suggest and let you know how I make out.
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post #8 of 13 (permalink) Old 12-31-2007, 02:55 PM Thread Starter
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Thanks for your help. I'll do as you suggest and let you know how I make out.
OK...so 45' of tinkering and rocking my low back yanking on the mothergrabbing pullstring and manipulating set screws it's no better off While I had it WOT I set the H screw and then adjusted the other screw next to it according to pitch of the engine. It got higher and spun higher as I adjusted so I thought it was going to fix my issue. Put the blade to a tree and same thing happens, bogs down.

I am DONE w.this thing!!
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post #9 of 13 (permalink) Old 01-01-2008, 12:03 AM
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Is the chain on backwards? Is the chain brake accidently engaged?
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post #10 of 13 (permalink) Old 01-01-2008, 10:26 AM Thread Starter
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Is the chain on backwards? Is the chain brake accidently engaged?
I guess the chain could be on backwards I'd feel really stupid if that were the case. I'll check another saw for chain direction. Brake isn't engaged either though it kind of behaves like it may be - i.e. it's slow to get going and then drops quickly when off the throttle.
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post #11 of 13 (permalink) Old 01-01-2008, 11:27 AM
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Just because the saw turns faster with the carb adjust does not mean it running correctly... in fact it most likely is running too lean. Start with the carb screws out 1 3/4 turn from fully closed and adjust from there... the final adjustment should be no more then 1/4 turn from that position.

My suggestion is to take it back to get it fixed under warranty. You can void the warranty by working on it yourself.

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Last edited by hankster; 01-01-2008 at 11:29 AM.
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post #12 of 13 (permalink) Old 01-02-2008, 04:13 AM
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make sure the chain is sharp also....when the saw was new...if you came out the gate
sawing a lot of wood...it wouldn't take long to dull it...

a saw running great with a dull chain won't cut worth a darn...great investment is a chain file...and sharpen to correct angles....keeps mine throwing chips of wood
on a steady base

cajun

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post #13 of 13 (permalink) Old 01-21-2008, 03:17 PM
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Sounds like a crank seal to me--but theres a lot of little things that cause the same problem. Iv seen this on brand new saws.
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