Echo PB-251. Wont run full speed,changed ,plug,filters

Wow! with all you have done it should run. Be sure the switch is on but if you are getting spark, it should be on. I would take it to the echo place for service.

loosen gas cap. Probably a bad Vent in the gas cap

You need to check your gas line and the primer ball itself and make sure you don't have a split in the lines or in the ball, also check the fuel filter in the gas line to ensure it is not plugged up.

I know you checked the plug, but it can fire outside the cylinder and then not fire under compression.
If you have compression, fuel, and spark at the right time you should get combustion.

I've been fighting with an Echo PB-251 blower and an Echo SRM-225 string trimmer since near the end of last lawn season (this is the forth season I've had them). Along comes a thread on a firearms forum and lo and behold the answer to the problem is spelled out in terms even I can understand.

After reading that thread (which attributes the problem of the engine bogging down when throttle is activated to collapsing fuel lines) I was going to just replace the fuel lines, but I discovered that there are kits that include new fuel lines, rubber grommets, filters, clips and cap seals for about $13.00 each. Hell, the kit for the SRM-225 even provided a new primer bulb. Ten minutes after the UPS truck delivered them to my door I had both machines running like new again. If you've tried other things and it still hasn't worked I highly suggest you try this.

you can thank the EPA for your blower problem the EPA makes all brands of lawn equipent "tamper proof" with plugs and limit caps. not just echo......when we service an echo piece of equipment we let it "break" in and adj the carb as needed BEFORE it leaves my shop. dont hesitate to bring it back to the dealer, if they are reputable, they will do the adj while you wait......hope this helps. good luck

i have aecho pb 260l backpack style leaf blower and it will not start. it turns over well and has spark and reasonably new fuel. any thoughts

Echo carbs have a little black plastic plug covering the High speed adj screw..CA air pulotion control bs..So get that little black blug out and give the screw a little turn open and u should be good to go..It worked for me..on a PBL 251 blower..My Echo weed wacker has the carb also..Go to Echos site and download the parts break down for your unit and look at the carb page..You will see the plug and HS,screw..happing wacking and blowing

guarantee exhaust is clogged maybe not muffler but exhaust port pull muffler off check screen and muffler then look into exhaust port usually rectangular port is closed down with carbon pull starter slowly to lower piston then scrape out carbon with screwdriver clean as good as possible then blow cylinder out make sure to get all pieces of carbon out reassemble should run fine

Too much oil in gas.