Jonsered 621 fuel pump?

[Chris J.]

I'm parting out my Jonsered 621, and someone has asked for the fuel pump. Ive never heard of a chainsaw having a fuel pump, but I readily admit that I still have much to learn about chainsaws.

Hopefully the responses will also be useful to other AS members.

Here's a link to the IPL that I downloaded:

http://www.barrettsmallengine.com/partslist/jonsered621.pdf

Chrsi

 

[HiOctane]

There is no separate fuel pump.Gas is pumped by a diaphragm in the carb .Diap is working by the pulse received from the engine.

 

[w8ye]

All the chainsaws I've seen that were made in the last 50 yrs had pumper carbs on them like Walbro, Zama, Tillotson, and Bing.

 

[Chris J.]

There is no separate fuel pump.Gas is pumped by a diaphragm in the carb .Diap is working by the pulse received from the engine.

Yes /\. I've never seen a fuel pump in a chainsaw.

There's a thread here that mentions some Jonsered models using a 'guide block' for the fuel & impulse lines, but I'm thinking that was used on earlier Jred models.

 

[Ambull]

Some of the really old saws had some crazy fuel delivery systems, but that pretty much ended in the mid 1950's. After that I believe all the manufacturers put the pumps inside the carb.

 

[dave k]

I think it was the Jonsred XF that had a fuel injection system and it had a pump which is the hard part to find and set up.

 

[SawTroll]

Parting out a 621 is blasphemy! :msp_biggrin:

 

[Chris J.]

Parting out a 621 is blasphemy! :msp_biggrin:

Yes, it is, but I already have too many project saws because I'm a loser .

The shop that had the saw (it has a partial repair tag on it) started harvesting parts because the piston was "seized." Turns out all the p&c needed was a little Kroil and a couple of hours of soaking in the Texas sunshine. I love the shlurping sound a jug makes when the Kroil frees up the rings!

 

[SawTroll]

There is no separate fuel pump.Gas is pumped by a diaphragm in the carb .Diap is working by the pulse received from the engine.

:agree2:

You are right, as usual!

 

[jimbo1490]

Yes, it is, but I already have too many project saws because I'm a loser .

The shop that had the saw (it has a partial repair tag on it) started harvesting parts because the piston was "seized." Turns out all the p&c needed was a little Kroil and a couple of hours of soaking in the Texas sunshine. I love the shlurping sound a jug makes when the Kroil frees up the rings!

Must be an airplane guy. Only airplane people know about Kroil.:msp_wink:

Jimbo

 

[Cantdog]

Yes Chris there is no external fuel pump as everyone has said. I have heard people call the square plastic vent and fuel line block the "fuel pump. Probably because it looks complicated!! It is only a seperator/mount that seperates the intank fuel line from the carb fuel line and also is where your tank vent ball valve screws in and the vent line hooks to. All the pro Jonsereds of that era had these... 52/52E, 621, 80, 90 etc. The 49 SP and 70E however did not.

 

[MnSam]

Parting out a 621 is blasphemy! :msp_biggrin:

But when he is done i will love him and squeeze him and call him george. Chainsawr.com referred to it as a fuel pump, I now see it is a fuel block. Thanks much Chris for checking into this.

 

[sapwood2012]

Hi New User..

Some of the really old saws had some crazy fuel delivery systems, but that pretty much ended in the mid 1950's. After that I believe all the manufacturers put the pumps inside the carb.

View attachment 230847View attachment 230848View attachment 230849View attachment 230850

Can anyone help me identify this silver square thing attached to the outside of this Jonsered XF chainsaw of mine, recently purchased £40 on Ebay. I need to replace this, as you see from pics the balck diaphram within this is shot where it attaches to the brass nut/valve in centre. It isnt a filter as their is one at end of fuel line inside of tank, it isnt a breather as its an enclosed unti, it aint a pump as the Tillotson HL 98A carb on this saaw has one within the carb.. So what is it and most importantly, where can a source one in UK, or even just to replace the diaphram, which I also cannot work out how to remove it anyway.. Can anhyone pls help. To get this saw running once again.

 

[Chris J.]

View attachment 230847View attachment 230848View attachment 230849View attachment 230850

Can anyone help me identify this silver square thing attached to the outside of this Jonsered XF chainsaw of mine, recently purchased £40 on Ebay. I need to replace this, as you see from pics the balck diaphram within this is shot where it attaches to the brass nut/valve in centre. It isnt a filter as their is one at end of fuel line inside of tank, it isnt a breather as its an enclosed unti, it aint a pump as the Tillotson HL 98A carb on this saaw has one within the carb.. So what is it and most importantly, where can a source one in UK, or even just to replace the diaphram, which I also cannot work out how to remove it anyway.. Can anhyone pls help. To get this saw running once again.

I've never seen that before. Maybe giving this a bump to page one will get some useful answers. You might also try posting the same questions & photos in the Jonsered sticky thread at the top of the page.

 

[sapwood2012]

I've never seen that before. Maybe giving this a bump to page one will get some useful answers. You might also try posting the same questions & photos in the Jonsered sticky thread at the top of the page.

I can only guess from taking it appart and looking inside that its a check valve, stops fuel going back down line. Thats basicaly what the valve is doing. So what I have done is bypassed this by removing the shot diaphram and brass valve and ive bought an inline checkvalve and installed this in its place. Hopefully this will sort her out. I wont know till I receive the Tillotson RK88 HL carb service kit and give her a once over.
Will keep you informed, I will probably need some advice once I begin.View attachment 231379

 

[sapwood2012]

Yes Chris there is no external fuel pump as everyone has said. I have heard people call the square plastic vent and fuel line block the "fuel pump. Probably because it looks complicated!! It is only a seperator/mount that seperates the intank fuel line from the carb fuel line and also is where your tank vent ball valve screws in and the vent line hooks to. All the pro Jonsereds of that era had these... 52/52E, 621, 80, 90 etc. The 49 SP and 70E however did not.

So what is this that I found on a recently purchased Jonsered XF.. See pics. It works like a oneway check valve. Little brass valve with a paper diaphram attached. sits between the tank and carb. Mine was shot, was bleeding a little when it should have been preventing fuel going back down, valve shot I suppose. So ive bypassed this and inserted an inline check valve myself. See pics also.View attachment 231380View attachment 231381View attachment 231382View attachment 231383View attachment 231384

 

[Captain Bruce]

Must be an airplane guy. Only airplane people know about Kroil.:msp_wink:

Jimbo

Kroil has been in the industrial world for decades. Not sure what you mean by airplane people?

 

[Captain Bruce]

Yes Chris there is no external fuel pump as everyone has said. I have heard people call the square plastic vent and fuel line block the "fuel pump. Probably because it looks complicated!! It is only a seperator/mount that seperates the intank fuel line from the carb fuel line and also is where your tank vent ball valve screws in and the vent line hooks to. All the pro Jonsereds of that era had these... 52/52E, 621, 80, 90 etc. The 49 SP and 70E however did not.

where your tank vent ball valve screws in and the vent line hooks to.? The NOT fuel pump plastic square piece, has a hose nip on the underside, that accepts the feed line. Above the block, is a larger hosw port, that feeds to the small hose nip on the carb. Off to the side, is a second hose nip, and a 3"" hose with a coil of wire. Thats the vent. Where is the vent ball check valve?

 

[Cantdog]

where your tank vent ball valve screws in and the vent line hooks to.? The NOT fuel pump plastic square piece, has a hose nip on the underside, that accepts the feed line. Above the block, is a larger hosw port, that feeds to the small hose nip on the carb. Off to the side, is a second hose nip, and a 3"" hose with a coil of wire. Thats the vent. Where is the vent ball check valve?

The plastic one on the side feeds the carb....the vertical one that is metal and screwed in is the vent.....the ball check valve is inside that.

 

[Captain Bruce]

The plastic one on the side feeds the carb....the vertical one that is metal and screwed in is the vent.....the ball check valve is inside that.

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?