Fuel squirting of tank vent one purge bulb pressed.

[adw]

504024601

[Hunter]

5 minutes ago, adw said:

So the check valve in the center section of the carb is stuck ( the part with the outlet purge pipe connect ) this part seems to be available as a spare part.

 

Exactly this what I thought. part 40 and 35 in diagram and all things in between and above has been tested by replacing all of them from a working saw carb and the carb did not suck any fuel hence I conclude that problem in one on the a pathway in main carb body.

[Hunter]

I even tried removing the metering needle completely just to see in fuel will be sucked.

[Hunter]

I guess time to order new carb.

[adw]

Do you have a vacuum gauge? connecting one to the pipe may well open the check valve, will ordering this part be a better option rather than some crappy Chinese knock off carb. however as has been said the saw should still start, if you get it running it may well open the check valve.

[Hunter]

26 minutes ago, adw said:

Do you have a vacuum gauge? connecting one to the pipe may well open the check valve, will ordering this part be a better option rather than some crappy Chinese knock off carb. however as has been said the saw should still start, if you get it running it may well open the check valve.

I don’t have vacuum gauge. 
I guess problem is with main check valve which cause purge bulb to suck air rather than fuel from tank.

am I right thinking that the main check valve located in carb main carb body (see photo ) and not on Primer side of carb as those part was replaced but problem exists.

[bmp01]

[bmp01]

So you've got 2 fuel circuits in the carb, a low speed and a high speed.

Low speed circuit is fed via the bung in your blue circle and there is a little flap check valve on t'side. 

High speed circuit is fed via the small hole below the main jet / check valve assy.

If you have a piece of small dia hose, preferably soft silicone, you can hold one end over the entry hole and blow / suck to confirm the check valve operation. Adjustment screws need to be NOT bottomed out. Low speed circuit will flow a lot less than the high circuit.... 

 

[bmp01]

I'm confused by your experiment and statement that its not sucking fuel.

I see fuel and air bubbles in  the return line. So it must be sucking some fuel through the carb, no ?

I don't see any air bubbles in the line between carb and purge bulb, is that all fuel?

 

Edit: Looks like 100% fuel in the line between carb and purge bulb. I agree with Openspaceman, you have an air leak around the purge bulb, might just be a loose fitting hose on purge bulb, or a cracked leg on the purge bulb....

Edited February 28, 2022 by bmp01

[Hunter]

52 minutes ago, bmp01 said:

I'm confused by your experiment and statement that its not sucking fuel.

I see fuel and air bubbles in  the return line. So it must be sucking some fuel through the carb, no ?

I don't see any air bubbles in the line between carb and purge bulb, is that all fuel?

 

Edit: Looks like 100% fuel in the line between carb and purge bulb. I agree with Openspaceman, you have an air leak around the purge bulb, might just be a loose fitting hose on purge bulb, or a cracked leg on the purge bulb....

Picture is for the working carb. The other carb Seen in picture to the left.