jonsered cs2145 tank air vent

[monty]

I have read people's posts on changing the gas cap to address the venting issue. This saw does not seem to have the vented cap. Can anyone confirm?

Is there another vent somewhere on this saw? I have the tank off and on my coffee table and I still can't find it! If I put my mouth over the fill hole and blow it does not leak except through the fuel line. When I put my finger over that it will not leak anywhere.

The saw runs well for a one or two minutes and then bogs out. When I loosen the cap it will suck air so I think that is the problem. Prior to finding this I removed and cleaned the Zama carb on it.

Advice on this would be greatly appreciated.

Thanks.
Monty

 

[HiOctane]

The vent is located on clutch side.Its hidden in a recessed area,you will see a 3/8' round hole in the upper part of the tank.Its made with two plastic"cent",the outside one being the larger.You cant remove them w/o damaging them at least the outside one.Pour a bit of gas over the vent and see if the level of gas drop,it should drop.If not replace the vent and check after the vent has been removed if air goes"tru"the hole,because ive seen on some saw that the tank hole itself was blocked.

 

[monty]

cs2145 vent hole found

Thank you for the reply. I found the little white plastic 'plug' and picked it out easily with a dental pick. I then pressurised the tank (by mouth) and put my finger over the fuel line. I could hear the air escaping!

I replaced the plastic plug and it sealed again not allowing any air through. Is this a part that is supposed to be permeable? Is it supposed to allow air through, but stop fuel? Are they a part that is often in need of replacement? The saw is really not that old so I am looking for a fairly common issue I would think.

Can I get away with drilling a small hole in this thing or should I order a new 'plug"?

Monty

 

[HiOctane]

Thank you for the reply. I found the little white plastic 'plug' and picked it out easily with a dental pick. I then pressurised the tank (by mouth) and put my finger over the fuel line. I could hear the air escaping!

I replaced the plastic plug and it sealed again not allowing any air through. Is this a part that is supposed to be permeable? Is it supposed to allow air through, but stop fuel? Are they a part that is often in need of replacement? The saw is really not that old so I am looking for a fairly common issue I would think.

Can I get away with drilling a small hole in this thing or should I order a new 'plug"?

Monty

Ya,drill few tiny holes,it would be alright.They got a new type vent with a cap on it.It should allow air and a bit of gas comes tru.

 

[monty]

Bogging out after run a couple of minutes

I unplugged the vent successfully but I still have the problem of the saw bogging out after a few minutes of high running.

The saw starts and runs great up to this point. I can make several high speed loaded cuts before it bogs out. The carb has been carefully cleaned twice so I think I can rule this out. When it bogs no idle or carb adjustment seems to work. I think I have a greater issue here.

Has anyone seen this? Should I be looking at gaskets somewhere that allow air in when the cylinder is hot? It does seem to get warmer than I think it should.

Thanks
Monty

 

[HiOctane]

I unplugged the vent successfully but I still have the problem of the saw bogging out after a few minutes of high running.

The saw starts and runs great up to this point. I can make several high speed loaded cuts before it bogs out. The carb has been carefully cleaned twice so I think I can rule this out. When it bogs no idle or carb adjustment seems to work. I think I have a greater issue here.

Has anyone seen this? Should I be looking at gaskets somewhere that allow air in when the cylinder is hot? It does seem to get warmer than I think it should.

Thanks
Monty

Does it happen after you have stopped your saw for few minutes or while cutting?It could be a vapor lock problem.If you had an air leak,the idle would be unstable at idle.Check if the round hole in the top cover is closed with the plastic plug.

 

[monty]

Bogging out after run a couple of minutes

It starts bogging only after it has been cutting at high RPM for a few minutes. After this it will still idle and increase in speed slightly or part throttle. High speed is the only one affected. If I let the saw cool the cycle repeats exactly the same. ie, it works great at all speeds until it heats up.

I drilled the white plastic plug to let the tank vent breathe easier. When the saw dies I released the gas cap and there was no pressure difference now.

I am wondering if there is a seal or gasket that is losing its seal when the cylinder is hot. Further to this, I would not know how to test for such a failure.

This saw is just one of those puzzles I can't let go!

Monty

 

[HiOctane]

It starts bogging only after it has been cutting at high RPM for a few minutes. After this it will still idle and increase in speed slightly or part throttle. High speed is the only one affected. If I let the saw cool the cycle repeats exactly the same. ie, it works great at all speeds until it heats up.

I drilled the white plastic plug to let the tank vent breathe easier. When the saw dies I released the gas cap and there was no pressure difference now.

I am wondering if there is a seal or gasket that is losing its seal when the cylinder is hot. Further to this, I would not know how to test for such a failure.

This saw is just one of those puzzles I can't let go!

Monty

Looks like vapor lock the way you describe it.To check leak,you better take it to your dealer because you need a plate for exhaust and intake ports and also a pressure gauge,unless you have those tools.

 

[monty]

Thank you

Thanks for all your advice. I really am stumped on this one so I am taking it to the dealer because it is driving me nuts. I will post back when we solve her for all that are following this thread.
The Dealer is over an hour and a half away so it will be awhile.

Thanks again
Monty