Author Topic: Older CVA2300 - starting issue (fuel not getting through the carb)  (Read 438 times)

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Offline TommyC

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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.

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Offline Eccentric

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Sounds to me like your crank seals were failing.  20 years of service is plenty from rubber seals.  That's why it was leaning out.  Since you kept running it..............you may well have roached the piston and probably the cylinder.  Pull the muffler cover and baffles and take a peek at the piston through the port.

If it hasn't yet roached, then you can likely save it with a carb rebuild, new fuel lines, and new crank seals.  When the seals fail..........they can cause a lean condition two ways;

1)The engine can draw in air past the seals...........leaning things out.

2)The crankcase impulse signal (which drives the pump section of the carb) gets weak.  Causes the carb to lean out.

These saws have a LONG fuel line.  That requires both a good impulse signal AND a healthy pump section diaphragm in the carburetor.  It is also possible that a screen in the carb is clogged.

Crank seals are still available for these saws fron Poulan AND Husqvarna parts sources, including your local Husky dealer.  530019059 is the # for the seals.  About $4 each.  SKF4913 is the industry # for those seals.  Probably will be more expensive than the Poulan/Husky parts though...

Carb kit # is K10-WAT.  Easy to find.  Fuel line is 3/32x3/16".  Get 2 feet.

Offline 3000 FPS

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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.
PP 505, 475, 445.

Offline fossil

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I could be the fuel line is **** somewhere There's a lot of line in those. There could still be fuel in the line even if the carb isn't pulling it.

Good advice from both guys above. If you do that maintenance which isn't too hard, it will last you another 20 years.
Tim

Offline TommyC

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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.   ;D)

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.

Offline 3000 FPS

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If you decide to take on the repair yourself let us know what your doing and how it turns out.
PP 505, 475, 445.

Offline TommyC

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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?  ???

Offline 3000 FPS

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I would still pull the muffler off and look at the piston and cylinder to make sure there is no scoring.
PP 505, 475, 445.

Offline fossil

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

Offline TommyC

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I appreciate additional comments from 3000FPS & Fossil.  I lowered my pickup tailgate and went ahead and did the inspection Eccentric suggested.  I'm glad I did b/c it was very telling:  I got an eye-full.  Sometimes one never really knows until one looks & sees.

Wow, is that piston ever damaged.  I'm not sure about "roached" but the skirt is clearly scored.  Also, it looks like there's only one ring (compression ring?) and it's badly scored.  Unfortunately, I've never had a good parts diagram for this engine (hint, hint).

Anyhow, never mind for the time being about any speculation as to the carb. status.  The machinist in me says I should never try to run this saw nomo until the piston/ring & crankshaft seals are replaced.

I do see that cc seals are available; not sure about the piston/ring.

Thanks again for your sage advice, Eccentric - that was spot on.  >:(

 

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