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Discussion Starter · #1 · (Edited)
I have an Echo SRM-210 string trimmer that I've used for several seasons now, without a problem other than broken recoil starter that I replaced last year. This year, however, the thing absolutely refuses to start. I have tried pretty much everything I can think of:

- Used fresh 93-octane fuel with 2-cycle oil mixed 1:50 per manufacturer directions, with a dash of Sta-bil.
- replaced air filter, fuel filter, spark plug
- removed Zama carb, soaked in solvent overnight, and put it back together with a Zama carb rebuild kit
- checked compression, it gets up past 120 PSI
- magnets on flywheel seem to be strong
- not sure about timing, but the magnets pass the contacts on the coil unit just past piston TDC.

It *seems* like it's not getting fuel, but I'm not so sure. The primer bulb pulls in fuel just fine. At this point the entire engine is torn apart on my work bench, with the piston hanging out. There is no obvious scoring or anything other than a little discoloration on the sides of the piston and the cylinder wall. I cleaned the carbon deposits off the top of the piston but who knows if that will do anything.

This totally has me stumped. I've been doing 100% of all mechanic work myself on my car the past 11 years and have put 225K miles on it since I bought it, and have never come across anything I couldn't fix - including pulling the engine out myself and putting it back in. And here now this tiny little 2-stroker is kicking my butt trying to get it to run.
 

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I am thinking soaking the carb may have damaged the check valves in the carb. These valves are not replaceable. Did you use compressed air to clean the internal passages? I had the same issue with an Echo hedge trimmer. I was tearing my hair out trying to figure out why after a cleaning and carb kit it would not run properly. I wound up replacing the carb. Now I use an aersol carb cleaner to clean all carbs. No more soaking. A new carb is around $50.
 

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Discussion Starter · #3 ·
I am thinking soaking the carb may have damaged the check valves in the carb. These valves are not replaceable. Did you use compressed air to clean the internal passages? I had the same issue with an Echo hedge trimmer. I was tearing my hair out trying to figure out why after a cleaning and carb kit it would not run properly. I wound up replacing the carb. Now I use an aersol carb cleaner to clean all carbs. No more soaking. A new carb is around $50.
Saw other recommendations and videos saying that soaking the carb was fine, but not to use strong solvents or compressed air.

But it didn't even try to start before soaking it, nor does it after, so I don't think that made any difference.
 

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Soaking does not remove all of the foreign particals that can block the small passages. A general aersol carb cleaner will dissolve and force out any debris. Brake cleaner also works. Timing should not be an issue as rarely does the key shear on these units. Have you checked to make sure it has spark? When I used to soak, the directions said to do it for only 20 minutes. So, maybe overnight did more harm than good.
 

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Discussion Starter · #5 ·
Okay so I poured about 1/4 teaspoon of fuel inside the spark plug hole, put the plug in and cranked it, and it STARTED! Then died 3 seconds later.

So it's obvious it's still not getting fuel. I guess something in the carb is still gummed up perhaps? Am I doomed to just dropping the cash on a brand new carb? If it can be cleaned out and passages cleared I'd rather do that.
 
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