Sam R
8mm Socket
Okay folks, I need a couple more brain cells on this one.
I've got an 038 in the shop that I just put a new top end on... In? Whatever the way, it's got a brand new Stihl 52 mm (Magnum) p/c, base gasket, rings, etc. Also tuned the saw up with a new air filter, fuel filter, spark plug and replaced that godawful (and missing) grub screw tank vent w/ the superior Echo style vent. Also checked p/v before & after, and it checked out there. Seals are probably kind of old but it only leaked down .1 BAR in 20 seconds.
The old p/c were exhaust scored, looks like it overheated someway. Rings were stuck... There's pics if anyone wants. But it was toast.
Now it'll start, pretty easily. It'll pop most times on the first cold full-choke pull. Run strong for a few, maybe 20 seconds then run down and die. Restarts after a few pulls (once the pump fills up the carb again, I'm sure) but it's not stable.
Good impulse, too. Fuel lines are in good shape, no leaking.
I'm really suspecting the carburetor but something else that jutted out to me was that the tank doesn't seem to be pressurized. You know how when you take the inlet hose off the carburetor and don't clamp it hose will spew out? This doesn't do that. So I'm not sure if there's something about that which may be affecting running.
One final thing this saw has what I suspect is the original Bing (48A101) carburetor on it. I didn't take it apart because in my experience those old carb pump gaskets are ruined when you take the cover off and I can't easily replace that part. It has no outside issues - at least the throttle shaft isn't loose, it's not covered in tell-tale air-leak grime, and... Actually come to think of it I don't think I did a pressure test.
I'm open to all ideas.
I've got an 038 in the shop that I just put a new top end on... In? Whatever the way, it's got a brand new Stihl 52 mm (Magnum) p/c, base gasket, rings, etc. Also tuned the saw up with a new air filter, fuel filter, spark plug and replaced that godawful (and missing) grub screw tank vent w/ the superior Echo style vent. Also checked p/v before & after, and it checked out there. Seals are probably kind of old but it only leaked down .1 BAR in 20 seconds.
The old p/c were exhaust scored, looks like it overheated someway. Rings were stuck... There's pics if anyone wants. But it was toast.
Now it'll start, pretty easily. It'll pop most times on the first cold full-choke pull. Run strong for a few, maybe 20 seconds then run down and die. Restarts after a few pulls (once the pump fills up the carb again, I'm sure) but it's not stable.
Good impulse, too. Fuel lines are in good shape, no leaking.
I'm really suspecting the carburetor but something else that jutted out to me was that the tank doesn't seem to be pressurized. You know how when you take the inlet hose off the carburetor and don't clamp it hose will spew out? This doesn't do that. So I'm not sure if there's something about that which may be affecting running.
One final thing this saw has what I suspect is the original Bing (48A101) carburetor on it. I didn't take it apart because in my experience those old carb pump gaskets are ruined when you take the cover off and I can't easily replace that part. It has no outside issues - at least the throttle shaft isn't loose, it's not covered in tell-tale air-leak grime, and... Actually come to think of it I don't think I did a pressure test.
I'm open to all ideas.
