Jonsered 621 fuel pump?

[Cantdog]

https://store.chainsawr.com/products/jonsered-621-chainsaw-fuel-pump-kit#
This shows the feed line from the tank attaches to, & passes thru this square plate, continuing to run over to the carb. The vent is the short hose, which wouldn't reach the carb fitting. and, if the thread in fitting is a check valve, what does it stop from flowing?? The part #'s from the 49 and 621 IPL's are the same for different parts?

No.....The short line coming out the side of the block goes under the carb and up to the barb fitting on the right side of the carb...rather a special line in that it is much larger diameter where it attaches to the block than the rest of the line to the carb. Also it should be noted that the plastic fitting coming out of the block must pointed towards the right side of the saw. The wire spring wrapped around the end of the line is what we might call a hose clamp to keep the line on the carb fitting. The vent line comes out of the metal check valve screwed into the top of the block. Notice in pic this line has a sharp 180 degree bend in it?...this is on purpose....it is formed that way....this line goes up and over the choke shaft then back down under the carb and exits to the clutch area. This is the vent line not the feed. It is not connected at all to the fuel line in the tank. The reason it goes up, over the choke shaft and back down under the carb is that this forms sort of a "trap" like a sink drain. This works together with the check valve to keep the fuel in the tank but at the same time allows air to enter the tank to replace fuel used. Again.... the metal fitting and line are not connected to the fuel line in the tank....two completely separate systems operating in the same plastic block
The 49SP does not use the plastic block but does share the metal check valve with the 621 as well as the 52/52E, 66, 70E, 80 and 90. On the 49 and 70E the vent valve is threaded directly into the top of the fuel tank and the fuel line simply passes through a hole in the tank so that there is but one fuel line on the 49 and 70E as opposed to the two on the 621, 52/52E 80 and 90..

 

[Captain Bruce]

No.....The short line coming out the side of the block goes under the carb and up to the barb fitting on the right side of the carb...rather a special line in that it is much larger diameter where it attaches to the block than the rest of the line to the carb. Also it should be noted that the plastic fitting coming out of the block must pointed towards the right side of the saw. The wire spring wrapped around the end of the line is what we might call a hose clamp to keep the line on the carb fitting. The vent line comes out of the metal check valve screwed into the top of the block. Notice in pic this line has a sharp 180 degree bend in it?...this is on purpose....it is formed that way....this line goes up and over the choke shaft then back down under the carb and exits to the clutch area. This is the vent line not the feed. It is not connected at all to the fuel line in the tank. The reason it goes up, over the choke shaft and back down under the carb is that this forms sort of a "trap" like a sink drain. This works together with the check valve to keep the fuel in the tank but at the same time allows air to enter the tank to replace fuel used. Again.... the metal fitting and line are not connected to the fuel line in the tank....two completely separate systems operating in the same plastic block
The 49SP does not use the plastic block but does share the metal check valve with the 621 as well as the 52/52E, 66, 70E, 80 and 90. On the 49 and 70E the vent valve is threaded directly into the top of the fuel tank and the fuel line simply passes through a hole in the tank so that there is but one fuel line on the 49 and 70E as opposed to the two on the 621, 52/52E 80 and 90..

Thanks for this very consise clarification! Robin, you know your J REDS. So, this 621 cane to me needing a once over. Original owner brought a carb kit. Claimed he'd done the work last year, worked the saw, and stored it. Presumed the carb needed another cleaning. The hoses are in the position(s) as the owner had them. Now, it seems he had them ass-backwards......What I thought WAS the vent line, actually the supply/feed line, has been nipped off due to the end cracking.....it no longer reaches the carb nipple. The amber hose is connected directly to the top port/vent fitting, and he ran it to the carb. The saw runs fine on a squirt of fuel; I am swapping the lines with fingers-crossed confidence in your guidance.

 

[Cantdog]

Thanks for this very consise clarification! Robin, you know your J REDS. So, this 621 cane to me needing a once over. Original owner brought a carb kit. Claimed he'd done the work last year, worked the saw, and stored it. Presumed the carb needed another cleaning. The hoses are in the position(s) as the owner had them. Now, it seems he had them ass-backwards......What I thought WAS the vent line, actually the supply/feed line, has been nipped off due to the end cracking.....it no longer reaches the carb nipple. The amber hose is connected directly to the top port/vent fitting, and he ran it to the carb. The saw runs fine on a squirt of fuel; I am swapping the lines with fingers-crossed confidence in your guidance.

If the rest of the saw is in good order you'll find she will start and run fine with the hoses in the right place. The way it is now the carb is just sucking fumes frm the vent at the top of the tank, not fuel. Don't forget to run the vent line as I said earlier. Up behind the choke shaft, over the shaft and back down forward of the shaft and out under the carb to the right side clutch area. Also the fuel fitting on the carb needs to be turned down to about the 8:00 o'clock position to pick up the feed line. It will just turn down, it's not threaded, just a taper that can be in any position and then reseated with a light tap.. The position it is in now can/will create an air lock. Fuel is not pumped into a saw carb but rather sucked to the carb by the pump inside the carb.......you don't want an air bubble in the fuel line..