Chainsaw Repair

Hi, inhereted an 044 from a buddy of mine who's too old to use it.  Sat for 5 years.  I rebuilt the zama carb, which made a difference but I still can't seem to get it to really run right.

Performed a pressure test to check manifold and pulse tube, which are air-tight.  Didn't want to check the seals unless it was as a last resort.

I vacuum tested it and it held vacuum fairly well.  Shop manual says it should hold (in psi, which I converted to inches of mercury-Hg) 11.8 Hg for 20 seconds and not rise above 8.7Hg.  I vacuumed it down to 11.8Hg and after 20 seconds it was showing 10.4Hg, which is pretty good for a 20+ year old saw.

So here's my question:

I'd have to do a little more setup to do a quality pressure test with actual values, but I can measure vacuum easily.  So, if a saw holds vacuum, can I assume it's holding pressure?

Hey 660...thanks for the reply.

I did a pressure test, it just wasn't all that sophisticated.  I pressurized the saw by covering the carb w/ a 1/4" piece of plate steel I drilled holes through and using a rubber gasket.  Muffler was sealed with one of those Stihl triangular things between muffler and cylinder.  Pressurized it to about 10 psi.  The manifold got bigger, so I think I had enough pressure.

I checked the pulse tube and manifold for leaks with a soap solution.  They pass.

I did change the fuel filter, but did not change the fuel line.  I will order one of those.  Will also check cylinder base bolts. 

It feels like a fuel delivery problem to me.  The fuel tank vent on top has two fine screws- one about halfway in the line and another at the end of the line.  I took the line off completely and ran the saw and it didn't make a difference.  Are those screws correct?