Echo SRM-265T Backfire

[isacguy]

Echo SRM-265T will start and run okay, not really have power, and then when you floor it, it sputters and actually backfires and pops. I bought a new carb for it thinking that it was just another EPA carb problem, but it didn't improve the situation at all. I pulled the exhaust and checked the rings to see if they had possible stuck, and letting by gases, but they seemed fine, I suppose I could check compression, but it starts so well I just don't know, any suggestions?

 

[KennyV]

A weak spark will cause it to stumble when punched to full throttle, Is the plug ok?
:smile:KennyV
BTW... WELCOME to LMF!!!!

 

[isacguy]

Thank you! I will check that out tonight, I am honestly surprised at myself for not knowing the answer, such a simple thing to check right off the bat.....

 

[CajunCub]

A partly sheared flywheel key will do the same thing, It may even have loose screws in the coil mount or even a loose flywheel nut. But 2 cycle engine carberators don't cause a backfire. Timing with the flywheel does that..Good luck!

 

[isacguy]

Well, the spark plug didn't help, but I will check out the timing, I honestly have never had a problem with timing before on a 2 stroke, but that clearly must be the problem.

 

[isacguy]

Okay, so I pulled the whole thing apart and I am now down to the flywheel, which is on there REALLY tight, I am having a hard time getting the nut to crack loose. It may have slipped out of time but I kind of doubt it. The ignition is also in a good solid position. Is there anyway to check the ignition besides a simple spark tester? Perhaps independently on a work bench? Or is there a certain thing to look for while it is running with a spark tester in place?

P.S.- in the parts diagram I did not see a flywheel key. Does anyone know if there is actually a key in place or not, since this weedeater has a clutch? I hate to get the flywheel off only to realize there is nothing there, and attempt to get it back in time properly.

 

[CajunCub]

I get that you are not really that clear about the timing"Thing".....It is only a flywheel key. You have to remove the flywheel nut then the flywheel to inspect the key to see if it has been sheered. It is a half moon shape called a "woodroof" key that fit into the crankshaft and slots into the flywheel. You cannot see it without removing the flywheel. Just some helpful tips on removing it: Loosen the nut, Take "2" ballpene hammers....lay 1 face down on the side of the flywheel oposite the magnets, strike it firmly once with the other. That will knock it loose, no prying is necessary.

 

[isacguy]

Thanks, I get the timing "thing", pulled the flywheel, key is fine, no signs of being damaged. Any way to test a coil on a bench? I think Echo has a lifetime warranty on there ignitions.....