72thing
Chain dulling master
I recently have run into a problem that I haven't seen before. I'll explain in far too many details in the best way my brain can ramble on.
Both my 440 and my Ms250 are leaking fuel all over and under the carb out onto the tank and handle, making a nasty mess. It started recently, perhaps due to warmer weather, although I've never had any sort of problem before. I thought it was leaking from the fuel line where it connects to carb inlet, so I replaced the fuel line on both saws. (440 had original line that was still in good shape, but was getting soft near the carb, so I replaced with new green OEM line. 250 had aftermarket line, replaced it with new OEM line.)
When I picked up the 250 yesterday, it had been in partial sunlight and there was a giant mess all over the carb and down the handle again. I think the only place it can leak and wet the entire carb is the top gasket at the metering diphragm. I rebuilt the carb a few yrs ago with fresh gaskets/diphragms, and the gaskets still look perfectly fine. This has the newer style black tank vent with several holes in top, only vents into tank, but won't let pressure out. Vent is the same on the 440 and both vents are working properly.
I still have to pressure test 250 carb to verify, but I think its leaking from that metering gasket on top side.
I'm not sure if its as simple as another rebuild kit...
The reason I ask is because I did have time to pressure test the 440 carb (line filled with fuel and metering cover/diphragm/gasket removed, fuel on top of needle) and it was leaking bubbles through the pump side gasket at around 10-12 psi.; needle was holding fine up to Mityvac being maxed out, ~30 psi. And this is with new gaskets, even though the old ones looked fine. I did torque the carb screws more (especially the single screw for the pump side) and it seems not to leak/bubble as bad. But dang, its not like they were loose...Stupid question: anybody ever had to put thin coating of gasket dressing or sealant on carb gaskets?
It seems the slightest amount of sunlight allows tank to build pressure in either saw, so I really wish the vent worked both ways. Is making a new tank vent just a bandaid to the leaking gaskets? I've already studied it and figured out a workaround for both saws if'n I can't get the leak remedied.
Who else has run into this issue? Every saw I have marks its territory with bar oil, which doesn't bother me. But I can't stand the fuel leaks. This still sounds dumb in my head, as it's a seemingly simple problem, but its aggravating me, so throwing it to ya'll for proper diagnosis/ridicule
Thanks
Both my 440 and my Ms250 are leaking fuel all over and under the carb out onto the tank and handle, making a nasty mess. It started recently, perhaps due to warmer weather, although I've never had any sort of problem before. I thought it was leaking from the fuel line where it connects to carb inlet, so I replaced the fuel line on both saws. (440 had original line that was still in good shape, but was getting soft near the carb, so I replaced with new green OEM line. 250 had aftermarket line, replaced it with new OEM line.)
When I picked up the 250 yesterday, it had been in partial sunlight and there was a giant mess all over the carb and down the handle again. I think the only place it can leak and wet the entire carb is the top gasket at the metering diphragm. I rebuilt the carb a few yrs ago with fresh gaskets/diphragms, and the gaskets still look perfectly fine. This has the newer style black tank vent with several holes in top, only vents into tank, but won't let pressure out. Vent is the same on the 440 and both vents are working properly.
I still have to pressure test 250 carb to verify, but I think its leaking from that metering gasket on top side.
I'm not sure if its as simple as another rebuild kit...
The reason I ask is because I did have time to pressure test the 440 carb (line filled with fuel and metering cover/diphragm/gasket removed, fuel on top of needle) and it was leaking bubbles through the pump side gasket at around 10-12 psi.; needle was holding fine up to Mityvac being maxed out, ~30 psi. And this is with new gaskets, even though the old ones looked fine. I did torque the carb screws more (especially the single screw for the pump side) and it seems not to leak/bubble as bad. But dang, its not like they were loose...Stupid question: anybody ever had to put thin coating of gasket dressing or sealant on carb gaskets?
It seems the slightest amount of sunlight allows tank to build pressure in either saw, so I really wish the vent worked both ways. Is making a new tank vent just a bandaid to the leaking gaskets? I've already studied it and figured out a workaround for both saws if'n I can't get the leak remedied.
Who else has run into this issue? Every saw I have marks its territory with bar oil, which doesn't bother me. But I can't stand the fuel leaks. This still sounds dumb in my head, as it's a seemingly simple problem, but its aggravating me, so throwing it to ya'll for proper diagnosis/ridicule
Thanks
