String Trimmer won't start - pull cord resists (Tanaka TBC-260PF)

[BigPoker]

Cannot pull start this 2 cycle trimmer with a spark plug installed. Loads of resistance/binding from the pull cord. Without a plug, it pulls easily and smoothly. It's almost as if it's compression locked with a spark plug installed.
There's plenty of spark and fuel. I removed the muffler and inspected the spark arrestor - other than a lot of fuel in the muffler, the arrestor screen was perfectly clean.
There was also a lot of fuel in the cylinder/block - for that reason, and because it wouldn't start at all before the pull cord began to bind up, I threw a new carburetor at it, with new fuel hoses/filter (the original intake hose was starting to get spongy and kinked from age).
The trimmer is 6 years old, and probably has 120 hours on it. It always was tough to start cold, but ran well hot. It has a 7 year consumer warranty but I don't know what that covers.

 

[merc_man]

Sounds like it is flooded.

Sent from my SM-G950W using Tapatalk

 

[BigPoker]

Sounds like there is so much fuel in the cylinder, that it ends up hydro locking itself.

Thanks for responding. If that's the case (flooded), other than letting it evaporate out over a few days (maybe?), what's the best way to dry it out? Take the plug out and let it sit?

 

[BigPoker]

I will try that. I read somewhere to take the spark plug out and give the cord a good 10 pulls with the choke off to vaporize the fuel. I tried that - and some vaporized fuel escaped and the piston moved freely - but the cord still resists once I reinstall the plug.
If that doesn't work, what's next?

 

[Larry B]

Take the spark plug out. Turn unit so cylinder has spark plug hole is facing down. Pull rope vigorously a couple dozen times. Put plug in and see if you can pull the rope.

 

[backhoelover]

Also need to find out why fuel is leaking into engine. Thinking stiff metering diaphragm

 

[BigPoker]

Take the spark plug out. Turn unit so cylinder has spark plug hole is facing down. Pull rope vigorously a couple dozen times. Put plug in and see if you can pull the rope.

Thanks for all the feedback.
I will try this spark plug hole facing toward ground and pulling cord suggestion tomorrow.
I think I can rule out that it's the wrong plug - it's the one I spec'd from the operator manual and that I used for the past couple of months late last year and early this year when it ran fine. Plenty of spark visible when grounding it, as well, even though that's not necessarily fool proof. I think it's more likely the piston got taller than I have the wrong plug. . But just to be 100% sure I will double check that tomorrow (I never rule out making an idiot mistake).
Also, just to be clear, I think there's a sequence here that's getting mixed up here, and that may be important. Before the pull cord issue, I thought there was a problem with the carburetor due to failure to start/hard start and with that issue fuel vapor/droplets I noticed coming from the muffler. The cord pulled freely then - no issues. That's why I swapped in a new carburetor.
After the new carburetor was installed, the cord became taught/resistant. I removed the plug and the cord pulled freely and smoothly. Put the plug back in and the cord is back to resistance/Then I disassembled the muffler to check the spark arrestor. And that's when I noticed liquid fuel accumulated in the muffler housing.

 

[alleyyooper]

Sounds to me as if the new carb is a bigger issue than the old one was.To bad it doesn't have a fuel shut off lever you could adjut the flow with.

Remember with a 2 stroke you will even get a crank case full of fuel in a flood condition too.

Al

 

[BigPoker]

Take the spark plug out. Turn unit so cylinder has spark plug hole is facing down. Pull rope vigorously a couple dozen times. Put plug in and see if you can pull the rope.

I tried your suggestion but there's no change. I also took the muffler off and tried to give it a few pulls. Similarly no change. The pull started is overcome by resistance if there's a spark plug installed. Even my thumb has the same effect. With the spark plug hole open, the pull cord can be actuated. I wouldn't say it feels like a smooth stroke though. I am beginning to think there may be something bent like the rod or main bearing that becomes apparent under compression.

 

[Larry B]

You got problems right here in river city. Sorry, just watched the musical the music man.
Unless you have a crap load of carbon builup in the combustion chamber looks like you have to pull it apart to see what is wrong.

 

[BigPoker]

You got problems right here in river city. Sorry, just watched the musical the music man.
Unless you have a crap load of carbon builup in the combustion chamber looks like you have to pull it apart to see what is wrong.

Thanks. I did a through inspection of the cylinder wall peering in from the exhaust port and spark plug hole with a flash light while slowly pulling the starter cord. There's no visible scoring and no carbon build up anywhere except the top of the piston (that's normal).
I also listened carefully and turned the flywheel by hand, having a hunch and by feel that the binding might be happening there. I definitely could feel it catching there at the flywheel, so I marked one of the fins. I kept turning the flywheel by hand. It binds on the same spot on the full rotation of the flywheel. This also happens to be just before the piston bottoms out, but when it rebounds the piston doesn't grab again.
All of this leads me to believe the problem may be with the flywheel, or maybe the main bearing(?). So it looks like I will take that apart. Any thoughts about what I should look for?