Not a chainsaw, but...

[hosocat]

I acquired an echo pb250ln blower that won't start or run. It has good spark, 135 psi compression, and vacuum and pressure check okay. It will sputter and want to run for one or two seconds, but then dies. Sometimes it backfires. I figured carb problem, so I bought a hipa new carb, lines, filter. No difference. Still backfires, sputters, and won't start. Any ideas what I might check next?

 

[sean donato]

Bad coil or flywheel key is broken.

 

[singinwoodwackr]

I acquired an echo pb250ln blower that won't start or run. It has good spark, 135 psi compression, and vacuum and pressure check okay. It will sputter and want to run for one or two seconds, but then dies. Sometimes it backfires. I figured carb problem, so I bought a hipa new carb, lines, filter. No difference. Still backfires, sputters, and won't start. Any ideas what I might check next?

Check the muffler screen. A known problem with Stihl blowers…

 

[Bob Hedgecutter]

Not to be hipa critical- but swap the factory stuff back and fix the timing.

 

[hosocat]

Bad coil or flywheel key is broken.

Thanks. That will be a new area of troubleshooting for me.

 

[Lightning Performance]

Thanks. That will be a new area of troubleshooting for me.

Timing is everything

 

[lone wolf]

Check the muffler screen. A know problem with Stihl blowers…

I just had that problem !

 

[Lightning Performance]

I just had that problem !

Switch to corser mesh on the screen.

 

[ZeroJunk]

Switch to corser mesh on the screen.

Or, unless you live in a fire prone area do away with it altogether.

 

[singinwoodwackr]

I just had that problem !

I’ve done 2 b86s with impacted filter cones so far. Either clean or just cut them off.

 

[ZeroJunk]

I’ve done 2 b86s with impacted filter cones so far. Either clean or just cut them off.

Sometimes I go through 30 or more blowers, weedeaters, and hedge trimmers in a week.
At least half if not more are either flooded or the screen is clogged up.
Five minute repairs.

 

[hosocat]

OK. It's not a sheared or bent keyway. It has great spark. I tried taking out the muffler screen earlier. I even tried starting it without the muffler because it has some honeycomb type material in it. Still wouldn't start.

Timing of spark might explain why it is sounding like it does. I pull rope and it will give one or two sputters, like it might when first starting with full choke, but that's all I can get.

Is it possible for the timing to be off on one of these?

 

[sean donato]

Depends if it has spark advance built into the coil. Also by checking spark, if you're just firing the plug in air it doesn't mean much. Need a spark tester to load the ignition circuit. They are dirt cheap.

 

[hosocat]

I fired it into air, and I also used one of those gizmos like a spark plug wire with a plastic bulb in line that flashes to show spark. Is that a spark tester like you're referring to? Both methods showed strong spark.

 

[Bob Hedgecutter]

I fired it into air, and I also used one of those gizmos like a spark plug wire with a plastic bulb in line that flashes to show spark. Is that a spark tester like you're referring to? Both methods showed strong spark.

Timing does not create the spark- it makes sure it happens at the correct moment during the rotation of the engine.
An engine with bad timing can and will create the perfect spark- but it may be doing so when the piston is closer to BDC than TDC.

 

[sean donato]

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I was referring to one like this, however the light with the plug in the cylinder is better then free firing the plug in the air.
Bob, is correct. Timing is independent of having spark. The spark needs to happen at the correct time.

 

[hosocat]

How do I check if the timing is correct on a 2 stroke? The coil is fixed, as are the magnets on the flywheel. What could cause the timing to be off, and how would I detect that?

 

[MAC 7-10]

I may have missed something but I believe the op was asking about an echo pb 250, not a stilh. Stilh's do have all the above problems but on an echo there is a small check valve in the fuel line in the tank than can give you fits sometimes and is often overlooked. Maybe worth a look. Usually down at by tank filter.

 

[sean donato]

How do I check if the timing is correct on a 2 stroke? The coil is fixed, as are the magnets on the flywheel. What could cause the timing to be off, and how would I detect that?

You don't, it's an internal coil issue. Unfortunately it's one of those, eliminate everything else then toss a coil on it. We'll, I guess you could get a battery powered timing light and mark TDC etc... usually coils arnt too expensive.

 

[Bob Hedgecutter]

I may have missed something but I believe the op was asking about an echo pb 250, not a stilh. Stilh's do have all the above problems but on an echo there is a small check valve in the fuel line in the tank than can give you fits sometimes and is often overlooked. Maybe worth a look. Usually down at by tank filter.

I figured carb problem, so I bought a hipa new carb, lines, filter. No difference.

So all the original factory stuff with any valves should be sitting on a bench or in the bin?