Vintage Jonsered 621

[landyman]

Hi there,

 

I have a problem with my fathers jonsered 621. Runs fine for a bit then pressurises the fuel tank and stops. I have checked everything that I know andcant find anything wrong so I'm figuring that pressure from the cranckcase must be seeping through into the fuel tank.

 

The real question is does anyone know where I might be able to source a gasket set for it. I have part numbers and have tried a couple of places in the states but to no avail.

 

Many thanks

 

Pete

[peatff]

It's not just the tank breather blocked ? Does it leak fuel when it's not in use how does the pressure get into the tank ?

[landyman]

nah I shouldnt think so. Disassembled brather and all and gave it a good blow out with airline. Tank is pressurized with bubbles in after running for 10 mins or so.

[spudulike]

If you can't find a gasket, buy a sheet of 0.5mm gasket paper and make one, been there before, it is dooable!

[adw]

621 with fuel in the crakcase rather than having a seperate fuel tank suffers terible with todays fuel, it will actually boil in the tank after a short period, as much as it pains me to say this try Aspen, bugger that really hurt.

[C.J]

621 with fuel in the crakcase rather than having a seperate fuel tank suffers terible with todays fuel, it will actually boil in the tank after a short period, as much as it pains me to say this try Aspen, bugger that really hurt.

 

That explains it .My uncles old Jonsered used to pressurise the fuel tank and I never understood how it could happen

[adw]

Yes Husqvarna 65/77 would also boil the fuel in the tank, then run like a drain.

[landyman]

That is exactly the symptoms! I'll go and get a bottle of badger tears and try it. lol.

[SawTroll]

621 with fuel in the crakcase rather than having a seperate fuel tank suffers terible with todays fuel, it will actually boil in the tank after a short period, as much as it pains me to say this try Aspen, bugger that really hurt.

 

My 1970 vintage one always have ran perfectly, but that's with Aspen alkylate premix - not pump gas.....

[landyman]

Evening guys. Just a follow up from this thread. Have taken advice and tried the old 621 on aspen, set the carb up just right and it runs just fine. None of the problems that we had before. Good advice. I'm sure theres plenty of older problem saws which could be cured by just changing to Aspen. Wow never thought I'd see the day that I used it.