abused poulan question

[sonoransaw]

Isn't it the other way around? Usually an air leak means you need to RICHEN or turn OUT the screws to allow for all the extra air from a leak. All the way in is pure LEAN. Am I mistaken?
When you say Idle screw do you mean the throttle butterfly adjustment? I am thinking you meant the Low Speed Mixture Screw. Both High and low should be between 1-2 turns out. I get the saw to idle, then rotate the low speed screw to get the highest rpm, then use the idle screw to put it at the right rpm per the service manual or where the chain stops moving (given you have a good clutch), then I set the high screw to just start four-stroking at full throttle and verify with a tach. My buddy Craig said he sets them for 11,000 to 11,500 out of the wood. The four-stroking should clear up once it starts digging in to the wood.

Thanks, Kenny, yeah I meant the throttle btrfly adjustment, not the lean screw....

Now I'm getting pissed. Came home last night, wanted to cold start the Poulan, make sure everything was ok, then get paid! NOPE! Now she has an erratic idle, up and down. She revs ok, needles are at 1-1/2 but holy crap is the idle ever erratic! The chain will stop, then spin like mad, then stop. I guess a pressure/Vac test is going to have to happen. A couple guys asked about fuel, etc. Everything from the lines to the filter to the carb to the canned fuel is NEW. I'm ready to turn it into a small boat anchor!

Did you ever get it figured out? I get frustrated fooling with my poulans, at least the one this thread is about (the 46 cc one does fine)....

 

[sonoransaw]

So I finally took the carb out again. When I put the new carb in there were several gaskets they sent. I had just picked one, but as I was thinking about it, I thought maybe the air leak was because of the wrong gasket. When I took the carb out there was gas on the surface of the gasket where there shouldn't have been. Anyway, after looking at the mating surfaces, I realized one of the other gaskets would fit better. I put it in and tightened everything up. It runs fine now. But as I was messing with the throttle butterfly adjustment screw, I can't see any difference in how the saw runs when I turn it in and unscrew it. Even all the way in (which is where I left it), the saw runs fine. Shouldn't screwing it all the way in cut off all air intake?

 

[KennyWinCT]

It should. One of them actually had an air leak on the fuel pump side that I verified by pressurizing in a glass of water. It was a BRAND NEW CARB! I have a few of these carbs both old and new so I tested until I got one that held 7 psi with no leaks and it made the saw run great. Now I have 2 more with some sort of air leaks. I'm really starting to hate these things! One thing though, make sure you have the saw fully warmed up before you start wondering about air leaks. Some saws run great when cold then get erratic once warmed up (seals), especially these Poulan cheapie saws.

 

[sonoransaw]

Yeah, I'm wondering if it's just cheapie carbs that are the problem... My Echo and Stihl both run perfect... Thanks for the tip on warm saws.... I am only reading it well warmed up. I let the 50cc poulan sit and idle a long time. Ran it a bunch. Let it sit idling some more. I'm pretty satisfied with it running now, except I can't figure that butterly valve thing.... Oh well...

 

[KennyWinCT]

Yeah, I'm wondering if it's just cheapie carbs that are the problem... My Echo and Stihl both run perfect... Thanks for the tip on warm saws.... I am only reading it well warmed up. I let the 50cc poulan sit and idle a long time. Ran it a bunch. Let it sit idling some more. I'm pretty satisfied with it running now, except I can't figure that butterly valve thing.... Oh well...

The brand new Carb that leaked was factory ZAMA too! Not Chinese. That's what really threw me.

 

[AVB]

Now the question is where were they leaking? Around the needle seat or insert, leaking because metering lever set too high, or otherwise? I have many Zama to have metering levers set incorrectly from the factory. And I also had a few older carburetor that I found leaking around the needle seat insert but these were used carburetors.

I haven't work on a setup that has separate air head since most that I have are mount to the carburetor as one unit. On those the air head is closed at idle but start opening as you opens the throttle. The PP5020AV must of used an early hybrid system. I do know that however that the carburetor on air do richer at full throttle due to the added air from the air head.

 

[KennyWinCT]

It was between the gasket and fuel pump diaphragm. The cover wasn't perfectly flat.

 

[AVB]

It was between the gasket and fuel pump diaphragm. The cover wasn't perfectly flat.

Then that got to be factory defect then if on a new carburetor. I wouldn't put it pass it as many of these are manufactured in China and assembled by robots. A whole batch can make it out the door before the problem is discovered.

So far I haven't ran into one like that but I don't buy many carbs either as I rebuild nearly every one that is already on the equipment though it is getting a harder to do so on the Stihls due to their tighter controls and dealers that refuse to have the repair kits available locally.