Chainsaw Repair

The pickup tube/screen thing is under the saw, in the bottom of the oil tank. A pair of needle nose pliers will pluck it right out, and stick it right back in. Again, blow air in the body tubes and check if all is clear.
It was.
 

Gas in, oil in, out to the yard to see if it worked.

Of course it didnt. 

At full throttle only a slight trace of oil being slung. Argh. In a previous attempt to remedy this before I drilled a hole in the oil cap, and stuck a red spray can stem in it, but had plugged the hole with a small screw as part of this rebuild.

it shouldnt need it.

Well I took the screw out and put the red tube back on, and it began to fling an almost acceptable line of oil when you gun it. Still nothing like it did new.
So I bored the cap hole out a little more and put an 18" long clear air line on it, partly to get it to breathe better and also, I wanted to watch the behavior of the oil in the tube.

it would seem the pump is making good vacuum in the tank, as long as it is running there is no leakage, and any oil that creeped up the tube is sucked back in the tank in no time.

When you shut the saw off, the pressure differential forces the oil back up the tube.... pretty much like youd expect.  The larger bore tube and air hole works almost normally, and you can maintain a thin oil spray/fling at near full throttle as you would be running when your chewing through a log when oil is needed.

At slower speeds it seems to drip enough onto the bar so when you gun it a little, you get some normal fling.

So the saw is useable now, with reg motor oil.... why it continues to vapor lock with all new parts is anyone's guess. This setup works ok for me.
Next fill up I will use thick chain oil and block that air tube from the cap, on the remote chance that thick oil MAY pump out faster due to its thickness, allowing the pump to work more efficiently.

My old saws fling oil no matter what you dump in them and none of em have ever failed to oil. Good thing this saw starts so easy and runs so smooth, or I'd sell it. There is a lot to be said for smooth running and easy starting.

I did put the old duckbill in the end of the breather tube i installed... it works perfectly, and doesnt leak.
there is now however a puddle of oil under the saw when sitting but thats no real problem.... its oil and its better than no oil.

has the 4 bolts that hold the engine in been looked at? if they come loose the gear won't mesh with the pump..... it doesn't take much either.

Have the same problem with my husqvarna 435. Brand new , oiled for the first few tanks and then nothing. Using husqvarna oil 80 F outside and saw is clean.  This is my second husqvarna, the first ( 30 years old and used every year to cut fire wood)runs great never a problem. Everything is junk nowadays. Last one I buy.