Echo blower no-fire mystery

[Deane]

I am trying to fix an Echo PB-250LN hand-held 2 stroke leaf blower for a freind. It had no spark so I narrowed it down to a bad coil. The coil part number is listed as A411000501. Found a used coil that looks identical except the outside plastic is dark blue instead of grey. It is made by the same company, Oppama, (stamped C11907) but the part number is slightly different, ending in 251 instead of 501. I installed it and now I have spark as demonstrated by removing the plug and placing against the block and pulling the starter. When the plug is re-installed it refuses to fire... even when using starting fluid sprayed into the carb or the cylinder! I have never seen an engine that would not even pop when this is done. Anyone have another idea about what might be wrong? Thanks.

 

[MarkEagleUSA]

Flywheel key sheared causing timing to be off?

 

[Deane]

I was wondering if anyone had ever seen a case where the plug would fire outside the engine but the compression of the gasses in the engine
somehow prevented it from firing.

 

[bigbadbob]

I was wondering if anyone had ever seen a case where the plug would fire outside the engine but the compression of the gasses in the engine
somehow prevented it from firing.

Yes!! Dont be fooled!!

Try a new plug!!
And its only a few bucks.
BBB

 

[Redfin]

Spit balling but maybe the new coil has slightly different timing than the old. Either firing before or after it should.

 

[Deane]

Hmmm, no luck yet but found this video of a guy whose blower had spark but would just barely pop. He said it sounded like the timing was retarded. He found out that these modules are able to change the timing so it is possible that the module has failed and has radically changed the timing. Here is the video:
http://www.holidaychaser.com/vacationvideos/index.php/0h2dfWhaTgq2Ysh/comments.html

 

[Fish]

Have you reversed the wires?

 

[kalhoun]

Have you reversed the wires?

i had same problem, key was sheared on fly wheel, throwing timing off. bought new fly wheel

 

[AVB]

A411000501 PB250 blower ignition coil
A411000251 SRM265 trimmer coil

And yes the timing is different.