echo pb603 backpack blower will not start

[kkelly311]

I am working on a friends Echo PB 603 blower and cannot even get it to fire. Here is what I know. There is good blue spark, there is fuel (plug is wet and I have even put a little in the jug), plug is gapped correctly, compression is 90 psi, and the flywheel has no issues with the key on the crankshaft.

I have not removed the head to inspect the rings at this time (that may be next) or tested to see if a cylinder bolt may be loose. At this moment I thought there may be some issue with the switch wiring so I disconnected it from the ignition coil and still nothing. One more thing to note is that the ground wire from the switch (when I got the blower to work on), which is an eye-hook kind of ground end, was attached to the plastic ignition cover (I assumed that the mounting screw completed the ground). The bizarre thing is just to the left of place where I have the ground, there is another screw with a copper colored connector, but nothing to connect to. Not sure if that is where this ground should be as there are no other wires on the blower.

Anyone know what could be the issue and/or know where that ground wire really goes? Thanks

 

[kkelly311]

update

I took the muffler off (to visually inspect exhaust port), put a few drops of oil in the cylinder, put a little fuel in cylinder, and got it to fire briefly. I then checked the cylinder bolts and tightened them (only one barely moved) and got the blower to run. To tighten the 4th cylinder bolt, I need to remove the rest of the heat shield and take carb off and I will do that this weekend. So I will replace the cylinder gasket, put new rings on it (since the existing are quite old), change the oil seals since they are old, and go ahead with a carb rebuild as well.

 

[AVB]

I took the muffler off (to visually inspect exhaust port), put a few drops of oil in the cylinder, put a little fuel in cylinder, and got it to fire briefly. I then checked the cylinder bolts and tightened them (only one barely moved) and got the blower to run. To tighten the 4th cylinder bolt, I need to remove the rest of the heat shield and take carb off and I will do that this weekend. So I will replace the cylinder gasket, put new rings on it (since the existing are quite old), change the oil seals since they are old, and go ahead with a carb rebuild as well.

Most likely it is a struck piston ring and cylinder could be damaged. You need around 120 psi for it to run. I just finished up on a Husqvarna blower that 100 psi the start with that would not start and it was just a carbon up piston ring and groove. It was cause by a leaky needle valve seat. It was around the outer part of the seat where it was pressed in.

 

[kkelly311]

just wanted to follow up on the diagnosis. After doing all of the listed items in the original post.....Turned out that the carb diagram on a parts site was incorrect (with respect to diaphragm and gasket order on one side). Went to the carb mfg site (in this case it was Zama) and found the issue. Blower runs great now.