Echo PB-250 wont rev

[pelhamjeff]

Hi guys, this blower came in as a no start. It had no spark so I put a coil on it and that got it to start and run, but it wont rev nearly high enough. Sounds like maybe 5,000 RPMs. Compression is 120 PSI. Piston and rings look great. Exhaust port is clean as a whistle and so is the screen. I tried adjusting the high speed needle to no avail. Also tried giving it a little extra shot of fuel sprayed in carb inlet while it's bogging, which kills the engine. I had another one of these blowers do this exact thing last summer and the customer bought a new one so I never figured out what was wrong. I don't work on many echos so if somebody knows what happens to them, I'd sure appreciate some guidance.

 

[pelhamjeff]

Here's an update: The flywheel key looks great. I also took the jug off and the piston ring was stuck. I freed it up and reassembled, but no improvement.

 

[Homer6679]

Does the carb have limiter caps on it? Air filter clogged up?

 

[pelhamjeff]

Took the "limiter" off early on and I've pretty well ruled out this being a carb problem. Air filter is fine. Thanks for your input though..

 

[Homer6679]

Is the problem consistent or just when it’s warm or cold?

 

[pelhamjeff]

Constant

 

[AoxoMoxoA]

Sure sounds like a carb issue…

If I’m not mistaken, does that blower have that the Zama carb that has the “hidden” H & L jet screws?

If so, that carb doesn’t have limiter caps, but there are tiny black plastic plugs pressed in, which block access to the screws. You would need to dig them out to get to each of the adjustment screws. The low screw is on the top black plastic part of the carb where the throttle cable connects, and the high on the bottom carb body, under the primer bulb assembly, between the fuel inlet and return barbs.

Those carbs are notorious for falling out of adjustment and introducing a bogging down situation. Most of the time, the high screw needs to be opened up.

Kind of a stupid design, obviously made to discourage adjusting, except by an “authorized” Echo dealer.

 

[pelhamjeff]

Sure sounds like a carb issue…

If I’m not mistaken, does that blower have that the Zama carb that has the “hidden” H & L jet screws?

If so, that carb doesn’t have limiter caps, but there are tiny black plastic plugs pressed in, which block access to the screws. You would need to dig them out to get to each of the adjustment screws. The low screw is on the top black plastic part of the carb where the throttle cable connects, and the high on the bottom carb body, under the primer bulb assembly, between the fuel inlet and return barbs.

Those carbs are notorious for falling out of adjustment and introducing a bogging down situation. Most of the time, the high screw needs to be opened up.

Kind of a stupid design, obviously made to discourage adjusting, except by an “authorized” Echo dealer.

Not sure if it's a zama but it's definitely one of those rotary carbs or that's what I call them. That little black plastic plug you refer to is what I was calling the limiter. Anyway, the customer bought a new blower and gave me the old one and I will post what it took to fix it if I ever mess with it again. Thanks!