1. My best quick luck has been to back-flush the oiling from the port by the bar backwards with compressed air or solvents.

2. Due to some system's designs a complete disassembly of the oiling system is needed for inspecting, cleaning and repairing.

3. I have found sawdust in the pump's filter, poor or bad fitting lines Etc.

4. Add low psi to the oil tank to see in this produces oil. Is the sys automatic only or does it have a manuel pump that is not working also?? If there is a manuel pump and quick fixes are not working, I would pull the pump to inspect it.

5. Please notice the info below will include the tank not being pressurized as a possible problem if all else is well. Approx how old, seasons, volume of use on the saw??

6. Do you have a link showing the saw's parts??

Info below found at:

http://www.doityourself.com/forum/outdoor-gasoline-power-equipment-small-engines/256782-homelite-xl-chainsaw-oiler-problems.html

On the XL model series units the oiler is actuated by way of crankcase pressure. You will have a fitting on the crankcase (in the vicinity of the carburetor) which in turn goes to the oil reservoir and pressurizes the tank. There is a small duckbill valve pressed into the tank that allows air pressure in but not out. This pressure feeds oil to the bar. There are two rubber lines involved to move the air from the engine and oil to the bar. This is a very lousy set-up and is notorious for failure. Areas to check are: duckbill valve, oil tank cap (if it leaks it won't seal and not pressurize the tank), supply and feed lines colapsed/plugged or in a worst case a leakage of the intake system whereas it can't possibly create the needed pressure due to crankcase leakage (seal(s), gasket(s), etc. related to the crankcase).

Additional sources from a search "homelite 330 chainsaw oiler system" at the address below:

http://search.yahoo.com/search?ei=utf-8&fr=slv1-&p=+homelite+330+chainsaw+oiler+system

Good luck! loger