Chainsaw Repair

I have an older Poulan CVA2300 (16" bar) which has served me pretty well these 20 years or so.  After not using it for several months, last weekend it started doing something I hadn't seen before.

For an hour or so, it ran/cut fine.  Then, it began losing power and seemed like it was getting leaner & leaner.  Finally it died and would not restart.   Spark plug was rather clean & dry - no sign of fuel.  (I isolated the plug and it's firing.)  I could tell that fuel was getting to the carb. - I could see it in the line.  I removed the carb and cleaned it thoroughly - every port/nook/cranny.  The only thing I didn't do is remove the HS & LS jets and blow those ports out.

I put it back together and still no cigar.

If I spay a little staring fluid in the carb throat, the saw will start & run for a few seconds, then dies.  It's not getting fuel.

Any thoughts?  Does this sound like the reed valve?  Should I remove that part and check it?

What's the most likely reason as to why fuel's not getting into the combustion chamber?

Any help is really appreciated.

Or it could be the diaphragms in the carb have lost their flexibility.   Also get some carb cleaner and when you take the carb apart spray out all the orifices including the high and low jets.  Count the number of turns in first before you take them out so that you can put them back to where they were.   

   Or like Eccentric has pointed out the Cranks seals have gone bad.

Firstly, I want to heartily thank all who chimed in - very helpful & sensible diagnostic thoughts from afar.

• Eccentric - at first you kinda scared me w/ your Draconian diagnosis but as I thought more about it, it began to make a lot of sense, especially given saw's age.  Yes, leaky crank shaft seals could well explain the symptom and both your points are well taken.  As you suggest, I'll pull the muffler cover and inspect the piston.  I wonder, on a scale of 1-10, how tall an order is it to change out the seals?   (I'm probably gonna be sorry I asked.   )

I checked w/ Sears PartsDirect
http://www.searspartsdirect.com/partsdirect/part-model/Poulan-Parts/Chainsaw-Parts/Model-2300CVA/1324/1503220/10037773/00003
and Jack's Small Engines and they neither said they could locate a carb. rebuild kit.  I'll search on the part. no. you provided.  Of course, teh carb. itself is out of production.

•3000FPS had a good suggestion re:  the diaphragms.  Those should come w/ a carb. rebuild kit.

• Fossil mentioned the fuel line.  Actually, over the years, the line has broken about once/year and I've replaced it w/ ⅛" Tygon tubing.  Because this tubing is clear, it's pretty easy to see if fuel is reaching the carb.  In virtually all previous cases when the line has ****, it's empty of fuel - a telltale sign.  In this case, I really doubt the line is broken b/c (as I said) I see fuel all the way up to the carb.  With Murphy's Law, I suppose anything is possible so I'll check it.

Overall, methinks the seals & diaphragms are the most likely problems.

Now we may have a case of chainsaw karma.

I'm not sure what I'm gonna say here helps or hinders the diagnosis, but on a lark I went out and and tried to start the saw this afternoon.  After spraying a bit of starter fluid in the throat, it started right up and ran like a top for several minutes until I shut it off.  Then I started it right back up - ran fine - then shut her down.

BTW, this is exactly what it did last weekend.  When it "died" on Sat., I tried to start it up Sunday morning and it did start.  It ran fine for a half hour or so, then went dead (that "leaning" I described).

Does this  tell us anything? 

Check the screen in the carb as Eccentric indicated and check your fuel filter as well.