Stihl 039 - understanding the oil pump

[Mickeyluv]

I've had my 039 from new and it's never been a good oiler - it just about managed with a 16" bar but with a 20" it runs just too dry for my liking. It's always used 1/2 tank of oil for every tank of fuel. Yesterday I decided to remove the pump and inspect it. For a good while now the adjustment stop has been broken off and I can see why - it's quite fragile and easily caught with a screwdriver blade.

 

I just want to clear up my understanding of how it works; It appears that the pinion is integral with the pump shaft and when rotated moves from side to side to provide the pump stroke. The adjustment is just a rotating bar with and eccentric stop machined at one end. The position of the stop when rotated limits the stroke of the pump. At least this is how it looks - is this correct?

 

With my pump I noticed a piece of plastic sticking out in front of the pinion at the opposite end to the adjuster. I pulled this out and it's about 1/2" long and is a piece of nylon detached from the drive gear and this limited movement. On the bench the pump now has strong pressure - you can't stop the oil flow even when turned by hand. I also made a note of the maximum stroke and the position of the adjuster, and scored a fine line on the pump body as a reference. However, even now it's back together and all lines good and clear, the chain still doesn't look like it gets enough oil. There's barely any fling off the end of the chain and it still runs 1/2 tank of oil to a tank of fuel.

[AHPP]

I’ve got an 039 with the same thing (apart from I run a 25” bar on it...). Would you be so kind as to make a short video on the bench, pointing at the different bits you describe please.

[Mickeyluv]

It's all back together at the moment. If I pull it back apart I'll do a video.

[AHPP]

Thank you very much. Please quote my username if you do.