Trouble with a newly rebuilt saw

[virtualguy]

I replaced the cylinder and piston in a Poulan Pro PP2050AV recently and I'm having trouble getting it to run right again.  It will start fairly quickly, runs a little rough, won't rev to full RPM, and eventually dies.  It then doesn't want to start at all until it cools down again.

While it did run for a bit I dialed in the L & H to "somewhere close", though hard to be certain until it's running correctly.

While I had it all apart I replace the plug, fuel, filters, and fuel lines.

Any suggestions?

For the record I know it would have paid off to toss this saw and go buy something else.   I decided to rebuild it mostly as a learning exercise and it has definitely been that.

Thanks in advance.

[Tacotodd]

Did you pressure test or vacuum test? That is probably not the problem, but it's always a good idea for a fresh rebuild on ANY saw. Because, things get missed! Did you also, 100%, make sure that all of of the hoses were flowing adequately and that there are no leaks. I mean some flow under about 6psi and for vacuum also. The list is long and I didn't see anything in your description that screamed at me EXCEPT, why were you readjusting the carb anyway. Did you tear it down to do a cleaning & overhaul, or did you put on a different one? 

Questions abound 

[tomalophicon]

Did you torque down the cylinder adequately? 

[virtualguy]

Did you pressure test or vacuum test? That is probably not the problem, but it's always a good idea for a fresh rebuild on ANY saw. Because, things get missed! Did you also, 100%, make sure that all of of the hoses were flowing adequately and that there are no leaks. I mean some flow under about 6psi and for vacuum also. The list is long and I didn't see anything in your description that screamed at me EXCEPT, why were you readjusting the carb anyway. Did you tear it down to do a cleaning & overhaul, or did you put on a different one?

Questions abound

Thanks.  I have what I need to do a compression test and it's fine.  I do not have tools to do a pressure test.  I've double checked fuel lines but will do so again.   When I purge it I see good fuel flow and no air if that's what you're asking.
I failed to mention that I did put a new carb on before the rebuild.   That was before I realized the problem was lack of compression.

[virtualguy]

Did you torque down the cylinder adequately?

Yes I did.  I'm fairly careful about applying proper torque. 

[fossil]

What type of sealer did you use for the crankcase cap to cylinder?

[virtualguy]

What type of sealer did you use for the crankcase cap to cylinder?

Loctite 515

[fossil]

Great stuff. 

I guess I should have asked if you changed the fuel line. There is a liner in the line that becomes detached and looks a bit like snot when it does. 

It plugs things up.

[virtualguy]

Great stuff.

I guess I should have asked if you changed the fuel line. There is a liner in the line that becomes detached and looks a bit like snot when it does.

It plugs things up.

This is interesting as it seems like it's being fuel-starved but I don't think I understand what you're describing.  I did replace fuel lines from tank to primer to carb and back.  Are you saying there is a liner inside those OEM lines?

[fossil]

Yes, It's a thin liner that turns to goo over time. It's an EPA thing to stop fume migration through the line wall.

Pull the fuel filter off the line and see it the liner comes out attached to the filter.

[SteveMorgan]

Hello, I had the same issue with my stihl chainsaw. It's been tough lately. I did a full clean and a pressure test. However, the issue was not resolved. Finally, my friend figured out what was wrong with the cylinder. It's now working properly, but I'm not sure if the problem will resurface.

[Al_Smith]

Some times the seals will become leaky after a short run because they heat up  but shrink and seal after it cools down . I had a Stihl 200T that did that .In addition some times the coils will fail because of heat and lose spark but usually recover after a cool down .
What happens to the seals is the buna-n material  will degrade  over time because of the ethanol content of the gasoline .Some people travel miles and miles to find non ethanol gasoline .I just figure it's something you have to deal with and just change the seals if they leak .I'm not going to travel 90 miles one way to find special gasoline to use in a chainsaw which is not a 1930 Rolls-Royce ,it's a tool .