Husqvarna 236 stalls at full throttle (2 saws, same issue)

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honda4life

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Hello All,

I own an Husqvarna 236. Light saw (38 cc entry level), more than enough to fit it's purpose for me.
This was a nearly new saw when I bought it.
Unfortunately the first use was heavy for this saw, dry wood, big pieces for a 16" bar.
The saw runs quite good at the beginning but always had the impression it's quite difficult to get the last fuel out of the tank without sudenly stalling.
After a while and a lot of heavy use, I blew up both crankcase sealings due to heavy damaged bearings, top end is okay.
Did a complete rebuild of the crankcase but never managed to get the saw running as supposed.
Did a carb rebuild because I supposed this was the issue... NOT.

Recently I bought an identical saw very cheap in pieces (for the chains), I was hoping changing parts could eliminate the issue.
My saw was reasonably tuned but did not run well well after decent warmup / some cuts.
Also here, everything remounted and the saw behaves exactly the same.
I notice the exhaust is getting very wet from the oil 1:33 as recommended > Too much fuel? Sparkplug looks dry.
Spark arrestor seems not to be clogged.
Bad fuel > Fresh fuel... no difference.

Bad tuning skills? Maybe but I doubt it.
I manage to get the saw running at idle, finding the sweet spot with highest RPM is possible but it's almost impossible to start the saw afterwards near this point so I richen (a lot), seems to work best.
They both keep running a little too rough even close to the point where the clutch engages.
High screw... tried almost every position in 1/8 increments.
Full throttle > dies after good and responsive acceleration.

I don't know what to do anymore.
Weak spot of the saws, Strato saws suck, ...?


Help is appreciated, thanks!
 
Compression feels good, I don't have a tester.
Oil 1:33 according to manual, Champion brand, not top quality i guess.
Piston rings... saws are almost new, initial spur gear/bar almost no wear.
 
if the crank seals leaked then it was sucking air running it lean, this can cause all manor of damage to piston/rings/cylinder. sounds like vapor lock
True, but why the second saw has exactly the same behaviour?

did you check the fuel strainer for restriction? fuel tank vent clogged? did you try cracking the fuel fill cap to see if it allowed it to run?
Fuel filter looks okay, filter ordered to test.
Tank built pressure a bit pressure so that's a good sign checkvalve from breather is okay.
Will try tomorrow to open the cap.
 
i also see failed spark plugs and coils exhibit this behaviour as well. take the filter off and try to blow through it, it should be very easy to do. when it shuts off test for spark yet?
 
Spark is strong and sparkplug already tested.
Filter cleaned as far as possible.

Will try to grab breather with pliers and check / clean.
Maybe some leaking fuel/oil will clog bronze filter?
 
then that really only leaves fuel and compression, compression test it when it shuts off then you know exactly where to go next! sawdust, dirt and or both mixed with bar oil are the enemies on saws.
 
I cleaned out the sintered bronze fuel tank breather, there was dirt on it almost not visible due to similar color.
Poked around in the tank with a screwdriver at the check valve.
Low screw response is a lot better, hopefully I can tune the saw tomorrow correctly (too loud for now outside).

Breather inlet is in really bad position I guess for dirt and some spilled fuel (and oil)
 

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