PP4218A (I know, a piece of something). Idles fine. When I engage throttle, it revs up and down dramatically. If I release throttle, it returns to normal idle. I tried carb adjustments (L and H) - based on Craig Kirkman's youtube video. Also installed a new carburetor, fuel lines, fuel filter and air filter. Cleaned out the spark arrester. Problem persists. About to give up on it. Any ideas or things I could try?
Surges then bogs with throttle
- Thread starter PTK
- Start date
My pick would be a large air leak causing the saw to be massively lean and once fired up, jumps from idle to screaming its nuts off with the application of throttle.
You have basically eliminated the fuel delivery possibilities with what you have swapped out already- so the odds are the problem lays deeper within the saw.
My first suspicion would be the bolts that hold the clamshell base to the cylinder are loose and it is sucking air at the joint- the most usual air leak of clamshell style saws.
Another area could be the intake rubber buffer/gasket thing that sits against the cylinder on these saws.
Either require a pretty complete strip down of the saw including clutch removal ( I think the flywheel can stay on with this model- but not 100% sure).
I would strip the saw down (good chance to thoroughly clean the saw) remove the engine pan, (lift crank and check piston while in there) clean it all up, remove old sealant and coat both sides with a known good liquid gasket material like Yamabond 4 or similar- NOT RTV, replace the pan making sure bearing oil seals are not pinched and reassemble the saw. Leave it overnight to cure the liquid gasket with tight pan bolts and see if that cures the problem.
If you continue to run with the extreme high rev issues, it will burn out the piston and scratch up the bore- if this has happened already, you are just about at the "give up on it" stage.
You have basically eliminated the fuel delivery possibilities with what you have swapped out already- so the odds are the problem lays deeper within the saw.
My first suspicion would be the bolts that hold the clamshell base to the cylinder are loose and it is sucking air at the joint- the most usual air leak of clamshell style saws.
Another area could be the intake rubber buffer/gasket thing that sits against the cylinder on these saws.
Either require a pretty complete strip down of the saw including clutch removal ( I think the flywheel can stay on with this model- but not 100% sure).
I would strip the saw down (good chance to thoroughly clean the saw) remove the engine pan, (lift crank and check piston while in there) clean it all up, remove old sealant and coat both sides with a known good liquid gasket material like Yamabond 4 or similar- NOT RTV, replace the pan making sure bearing oil seals are not pinched and reassemble the saw. Leave it overnight to cure the liquid gasket with tight pan bolts and see if that cures the problem.
If you continue to run with the extreme high rev issues, it will burn out the piston and scratch up the bore- if this has happened already, you are just about at the "give up on it" stage.
Google an IPL for the PP 4218 A and you will find an exploded parts diagram of the saw.
These are handy when you try to figure out what went where when you go to put it all back together.
These are handy when you try to figure out what went where when you go to put it all back together.
Got it all back together. Everything seemed good (note the use of past-tense). Compression, spark, etc. But just wouldn't start. I got frustrated with it - and my loss of time. Put it away for now and bought a gently used Stihl. I love to tinker, so I will revisit it later. Thanks for your help and ideas Bob!