Hey, I have a craftsman leaf blower that is only a few years old (maybe 3?). Anyway, last year it quit working. I can get it to run after many pulls and playing with the carb, but it runs really rough and sounds like it's missfiring. Plus it will only run for ten seconds and I can't adjust the throttle without it shutting off on me.
I have looked at the piston through the intake side, the exhaust side and from the sparkplug hole and it appears intact. Also, it seems to have good compression, and turns over smoothly.
I took the carb off and sprayed it with carb cleaner. All of the passages were clear. There were no cracks in the intake or bad gaskets/seals.
I was thinking it may be the ignition module, but I don't know how to determine if it is bad. It looks clean and there are no cracks. How can I determine if it is bad?
The spark plug and the fuel/oil mixture are also fine.
any ideas would be great
thanks
brad

 

When it won't start, does it have sparK? Is gas getting into the cylinder? This will narrow it down to either a carb/fuel problem or an electrical problem.

 

I forgot to mention that. I could tell it was getting fuel when I would start it because I could see the primer button fill up when I pressed and released it. After it started I don't know if it was still getting fuel properly.
I could not tell whether it had a consistent or properly timed spark. It took alot of pulls to get it to start, however on each pull I usually got some sort of response (although very small) like it was at least getting some spark; untill the last few times I tried to start it. I got no response from it whatsoever those last few times, so I pulled the plug wire and held it while pulling the cord to see if it would shock me; I felt nothing. I also tried putting a screwdriver in the end of the plug wire and holding it close to the engine to see if it would spark; I saw nothing.

Because when I played with the throttle or adjusted the carbs for those few seconds that it was running, I initially thought it was a carbuerator problem. But because it made no attempt to start the last few tries (even when I put fuel right in the cylendar- in other words there was no doubt it had fuel), and because I did not see or feel spark, I then thought it was a spark problem.

The last time it was used, I was told that it all of a sudden started to run rough and like it was missfiring, so the person who was using it shut off, but could not get it to start back up. At the time this happened, he probably had it running wide open for an extended period of time (could have been close to an hour). I don't know if that makes a difference.

 

running it at full throttle wont hurt a 2 stroke engine. these motors are built to run high revs. from what you describe, I think your coil is bad, though first before just buying a new coil, look for any wires with damaged insulation touching metal. if there is, just fix that first, then try again, and it might save you a good bit of money as opposed to replacing the coil.

 

If it only runs a few seconds and shuts off it is the same as my craftsman was doing. My fix was a new carb diafram, the original had a fold in it and it never worked correctly. So after changing that it starts good, runs good and revs the way it should too.

 

Clint40 is correct. These carbs have a little fuel pump built in (like chain saws and weed-eaters) that actuate from the pulsation of vacuum. The carb has no fuel bowl (because its being turned upside down or other angles) and needs that type of design. You can run cleaner thru it but will probably destroy the rubber. If your iffy about working on the carb take it in for a rebuild or buy a new one. There about 50 bucks. I changed mine from a one screw-2cfm to 2 screw-3cfm carb (is that teakin' it or what...lol)

 

It sounds more like a carb problem to me. Best way to check for spark is to pull the plug out, put the wire back on it, ground the threads onto the engine, and watch to see if it is sparking. It is generally easier for two people, but one can do it fine. If you have good spark, then it's the carb. Take it off, take it apart, and see what it looks like inside.

 

What happens if it the diafram is that it will start because you prime it and it will run but then shut off as soon as the gas runs out because the diafram is not pulling the fuel. I actually was so pissed at mine I threw it from the garage one day and it landed in the drivway and my wife picked it up and took it to my parents house. Nothing better than an ole man with time to figure this crap out. We replaced that part changed the plug and she runs better than new.

 

I never did get the whole leaf blower thing. Where you blowin' 'em to, the neighbor's yard? I usually just hop on the riding mower and munch 'em up. Gives me an excuse to drink beer and drive around in circles.

 

I checked out the diaphram, and there are no creases or cracks. I disassembled the carb and cleaned it up. It's a very simple carb, and everything looked intact and clean. I guess I could just rebuild the carb but I hate to throw money at it without knowing the problem.

 

My snowblower was doing the same thing. I'd fire it up, it ran real rough and then would die. The fuel had the green stuffin it to preserve it, so I was pretty sure it wasn't the carb, but I looked anyway. I changed the plug and it has run perfectly ever since. One plug in about 10 years..go figger. I also have a craftsman leaf blower/vacuum mulcher. Its only on its second season and the only problem Ive had is when I bump the choke and it floods itself dead. But it starts again after a few brisk tugs. If all else fails, replace the plug. ( The old one looked fine too...nice and clean, proper gap, etc.)

 

Leaf blowera are the best thing ever. Any how, sounds a bit different than mine did but there is a small screen in the muffler that easily cloggs up especially if you richen your gas mixture, when this happens it will not run for more than a few seconds. But usually there is a loss of power over a few uses not all the sudden. Never hurts to look at it though.

 

Kinda random and off subject, but yeah those little two strokes will haul. The .45 CI motor in my model airplane will hit a little over 14,200 RPM with a 9"x4.5 propeller.
Painted the tips of it bright red so I could tell where the arc ended, at that speed, it blends in. Will hit 1.7 horsepower at full throttle though! lol feel them horses run!

EDIT: another random post: highest I have ever seen was a two stroke model boat engine rated to 32K RPM!!! .21 CI displacement.
*raises hand slowly* I'll give someone a dollar to stick their finger in it! JK!

 

Thread moved to General NON-Automotive Discussion.

-Matt