Hi, All - First time post after lurking for a while.

Having trouble starting my Echo SRM-210 string trimmer. Starter rope pulls smooth when the spark plug is removed, but is jerky and hard to move when plug is in. This happens with the plug wire disconnected, with the carb removed, and with the muffler removed, as well.

Could there be too much compression? Feels like that's the issue. Perhaps carbon buildup at the top of the cylinder??

I got the trimmer for free recently and ran it 2-3 times. It ran fine though it was hard to start. Problem has gotten worse and trimmer won't start any more. Fuel tank grommet was disintegrating (have since replaced), so gas/oil may have been evaporating and ruining the gas/oil mixture for a while.

So far, I've cleaned the carb, checked the flywheel key (ok!), removed starter assembly and checked rope spring (seem fine), checked for spark, cleaned some carbon blockage on the cylinder exhaust. No obvious scoring of the cylinder or the piston is visible.

Appreciate all the info on the forum! Any help here would be appreciated.

 

Is the plug wet after trying to start it? Sounds like it's either getting too much gas and hydro locking or there is a lot of oil in the engine, raising the compression.

 

From the time you got the trimmer and it would run, compared to now, has the jerky starter rope pull gotten worse?

 

Cheese - I didn't notice the spark plug being wet, but I didn't check for that (new to engine repair). Have a new plug in there now.
marbobj - It has gotten a bit worse, I only got it to run 2-3 times and it was already difficult to start. Once going, though, it went no problem.

I'm wondering if I should take apart the cylinder and head to try and clean, or just let it all soak in some seafoam, then reassemble, add some fresh fuel, new fuel filter, and see if that helps.

 

I wouldn't dismantle it. You can put a couple tablespoons of seafoam with oil down the plug hole, let that sit for a couple hours and drain it out the plug hole. After it starts that should get rid of carbon, if that's the problem.

Since you have the carb off (but you can still do this with it on)move the piston to top dead center and stand the trimmer with the carb port down for a few minutes. See if anything comes out of it.

Keep in mind, though, a two stroke has a lot of compression and the jerky pull cord you have may be normal and the hard starting may be a fuel or ignition problem that's unrelated.