I want to share my story. I know this is an old thread, but it is a good one with a lot of helpful tips. After today, I have more to add. After reading all of this, I was itching to pull out my very hard to start backpack blower and try some things I read. I bought my pb602 used from a guy for $150 about 2 1/2 years ago. He was some kind of small contractor that was downsizing and just didn't need it anymore. Pretty sure he bought it used from somebody else. He said it was always hard to start, especially cold. Don't think he ever used it much because of that. When he showed it to me, it must have taken him almost 10 minutes and 30+ pulls to get it started. Every once in awhile it would pop, but not start. Once it did start, it ran like a champ. It was worn and used, but not abused or in horrible shape so I gave him his money and just figured it was old gas or some easy fix. Got it home and only used a couple of times that first year just because I didn't have much of need for it AND it was hard to start. Got it out last spring, couldn't get it to start, even with mostly fresh gas. I mix Stabil in with my 2-cycle gas cans, just because sometimes it sits around without being used for months. Had to replace the primer bulb then, too. Fooled with it a couple of times, got lucky and got it started a few times. Only really used it once or twice because it was so hard to get started. It would flood in no time. I would pull the spark plug and see it was soaking wet with gas. Sometimes gas would even start dripping out the muffler. So I would pull the starter rope a few times with the plug out, choke off, to help dry it out. There were a few times that I never could get it to start at all and just put it away in disgust. I am actually a pretty good mechanic and have worked on all kinds of equipment. A few years ago I was even the full time maintenance mechanic for a landscape/mowing company. Anyways, this blower was really starting to get the better of me. I was figuring I would have to tear it apart this spring and do all kinds of work to it or just sell it to someone and be done with it. I downloaded a copy of the Echo manual for my blower right before I found this article, just so I could read the proper cold start instructions. Anyways, after reading both the manual and this article, I got out the blower to see what I could do with it. It was getting late and I really didn't have much more than 10 minutes to fool with it. Here is where it gets interesting. I haven't done anything with it in 4-5 months. Checked the gas, had a little bit left in it from last summer, enough to try it. I didn't really have time to drain it and refill it with "fresh" gas. TRIED to push the primer bulb, but it was pretty chilly today- maybe 45- 50°. That aftermarket (Arnold) primer bulb I put on last year just would not move. It is difficult to reach in the first place and is very hard to squeeze even in warm weather. I picked up the blower and saw there was gas in the primer bulb, so I thought what the heck, just skip trying to prime it. I opened the throttle about 3/4 of the way to full throttle. I know from having had it run before, that position pretty much wide open. Which, IS NOT, what the manual says to do. The manual says open the throttle to the start/idle position, which is about the lowest throttle setting. Anyways, closed the choke. Gave it two weak pulls to build up some compression. Third pull was a good yank. It started right up. It has never started that easily. I moved the throttle down a little and let it run a while. Gradually started to open the choke as it warmed up, but I did it too fast and it shut off. So, I closed the choke again and opened the throttle back to 3/4. Gave it one firm pull and it started right up! It has never done that either. I let it warm up 2-3 minutes then shut it off. Tomorrow I am going to fill the tank and see if this new trick works again. Maybe actually do some clean up with it. What I learned about cold starting mine (but I could be wrong). Most of this is almost the opposite of the manual: 1) Don't use the primer bulb unless necessary. Only if you run it out of gas or otherwise know there is no gas in the carburetor. Using the primer bulb unnecessarily MAY contribute to flooding. If you see gas in the bulb, that probably is good enough. As long as there is gas in the carburetor, that should be enough. 2) Open the throttle to a wide open position, NOT idle/start, as the manual says. The more air flowing though the machine, the better. Less likely to flood. 3) Give it one or two weak pulls before really trying to start it. Helps to fill the combustion chamber with enough fuel vapor and build up compression. Besides not using the primer bulb at all, the two things I did different was to open up the throttle wide and give it two weak pulls before really trying to start it. Hopefully I won't have to deal with it flooding anymore

***" I got it to start but it seemed like it was flooded."*** The operative word here is "flooded". So lets discuss "flooded". When the engine is hot and does not want to restart.......Do you see any BLACK SMOKE out of the exhaust as the engine regains operation??? Or are you seeing "no smoke" in the exhaust, but the engine sort of "stumbles and falters" as it gathers RPM???? Black smoke out the exhaust, after an rather long period of cranking, is the keynote symptom of a hot, flooded engine. A rather long period of cranking that produces no smoke when the engine finally gathers RPM could be a symptom of "vapor lock" in the fuel lines and fuel pump. One way to determine if vapor lock is the culprit is to pour about a quart of cold water on the fuel pump, fuel lines, and carburetor before you try starting it when hot. Keep the water away from the spark plugs or you could "ground them out" (which would render the test "useless"). ...................................... In regard to ***"a small solenoid at the bottom. I can hear it click when I turn on the key. I am not sure what it is supposed to do."*** That is the fuel cutoff solenoid valve. Its purpose is to prevent "afterfire" (sometimes erroneously called "backfire") out the exhaust during engine shutdown. By design intent, you should turn off the "ignition switch" while the engine is turning about "medium RPM' when shutting down engines that feature a "fuel solenoid". This action does not actually stop the "ignition sparking" of the plugs. Instead, it interrupts the 12 volt current to the fuel solenoid. This causes the solenoid valve to close, shutting off the fuel to the carburetor MAIN JET. With the MAIN JET deprived of fuel, the engine begins to lose RPM, but the ignition system continues to "fire", consuming the last dregs of fuel in the engine AND purging the exhaust and muffler of any unburned fuel or hot combustible gasses (remember, the throttle is still open, so the intake is gulping air, but only air....no fuel). This prevents the loud "BANG" out of the muffler, (so annoying to the neighbors) and makes the machine an EPA Poster Child by venting no unburned fuel vapors to the environment (unlike stopping a hot engine by "killing the spark", as once was the norm).

Update: I changed the fuel and air filters. The fuel seemed to flow fine when pulling the old filter, so I don't think that was it. The air filter looked somewhat dirty, but not too awful. When I mowed again I made it through the whole yard stalling 3 times. 1st it was out of gas, so that doesn't really count, but it restarted fine. 2nd was when I was almost done, but it did restart. 3rd was right after I finished and it wouldn't restart, so I just put it away. Maybe the air filter helped some, but I kinda think the seafoam is clearing out the carbon and helping the most. Maybe it'll keep getting better and won't need to be opened up. If I pull and clean out the carb what gaskets am I going to need? Same will pulling the valve cover and the head. I'd like to get them before starting the job. And it is an L-head engine, I guess the type number is wrong. Thanks for all the help.

EGR valve, idle air control, or maybe the mass air flow sensor comes to my mind. Hopefully someone with more recent experience than mine will chime in. Bottom line is it could be a number of things. The only thing to do get someone with some diagnostic capabilties to have a look at it. There's a chance that that symptom indicates a particular thing a high percentage of the time on that particular car, but I wouldn't bet on it. Good luck.