Leaf Blower Story. What's wrong?

[Alleycat]

Chain of events: Got a Poulan SM 400 for christmas last year. Used it until leaves were gone and put it up. When leaves began falling again, cleaned the plug, put in fresh fuel mix, and it started right up. Fast forward a couple weeks, and It gets real cranky about starting. If it quits, it has to cool down before it will start again or it floods. Also seems to be losing a little power. Time to put up the Christmas lights so, first decide to blow off pine straw and leaves on the roof. Since Mama didn't raise no fool, I cranked the blower up before going up on the roof. Just as I step off the ladder, it quits running. Spend the next 10-15 minutes trying to restart. Short fuse, Lose temper, toss it off the roof. Spend next several hours taking the plastic housing apart and welding up all the cracks. Now the good part: To get the housing apart, the carb has to come off. No problem. It's so loose it was ready to fall off on it's own. The muffler also has to be removed and when I touched it, it also was loose. Actually, the muffler wasn't loose, the movement was the result of the whole cylinder assembly being loose from the crankcase. Hard to believe it was running before. I carefully seated the jug to case o ring, tightened the loose screws, and put it all back together. It cranked right up, ran great, and I used it for about an hour, then put it away. I was happy as a calm, even if the housing did look like Frankenstine. Yesterday I got it out, and pulled on it until exhaused, my shoulder wouldn't take any more, and it won't hit a lick. It sputtered a little at first but nothing since. I pulled the fuel line out and it is clear. The spark plug was dry, so I suspected I may have gotten the two lines from the carb to the tank switched. Pumping the primer bulb did nothing, so I switched the lines, and now pressing the primer pulls fuel up into the carb, so I guess I have them right. Tried to crank it again with no luck. Checked the plug and it's wet. Checked spark, it's good. OK, I got fuel, and spark, and compression, what's wrong?? I don't know squat about 2 stroke engines. Help Please!

 

[1wildthing]

The plug may be shorted. If they are wet sometimes they won't spark in the cylinder. Also you may be pumping too much fuel into the engine with the primer. Doesn't sound like a major problem.

 

[Alleycat]

Thanks 1 wildthing. Last night I squirted som Maevel Mystery oil in the cylinder. This morning I put the new plug in, and it sputtered on the first pull with the choke full on. Moved to half choke, pulled a few reps of 5 pulls each, and it felt like it was getting easier to pull. Like maybe it was sort of firing, but not enough to make it run. I pulled the plug and it was wet again, and warm. I wonder if the ignition module is not up to par. At any rate, I looked at my owner's manual and it is under warranty. I'm going to take it to the shop and let them figure it out. Hope they don't mind the scars on the housing

 

[M.D. Vaden]

Thanks 1 wildthing. Last night I squirted som Maevel Mystery oil in the cylinder. This morning I put the new plug in, and it sputtered on the first pull with the choke full on. Moved to half choke, pulled a few reps of 5 pulls each, and it felt like it was getting easier to pull. Like maybe it was sort of firing, but not enough to make it run. I pulled the plug and it was wet again, and warm. I wonder if the ignition module is not up to par. At any rate, I looked at my owner's manual and it is under warranty. I'm going to take it to the shop and let them figure it out. Hope they don't mind the scars on the housing

The screen in the exhaust - did you check it.

It's sneaky.

In the city, I remove my spark arrestor screens.

But it replicates a totally plugged air filter, but the dam is on the exhaust, not the intake.

If even sneaks by some shops once in a while.

 

[Alleycat]

Thanks M.D. I will pull the muffler off and check the screen. I need to do some searching to find out what muffler mods the chain saw guys are talking about. If I get it running again, it would be nice to have it souped up a little.

 

[Alleycat]

OK, I pulled the muffler and there are no screens. There is a hole the size and shape of the exhaust port on one side and a small hole about .175 dia on the other. There is a baffle plate over the small hole with several smaller holes to direct the exhaust forward. I blew air into the port side it seems to flow through the muffler, so I'm guessing that is not the trouble. Since the engine tries to start on the first pull when choked, then floods on successive pulls with half or open choke, I wonder if the carb is out of adjustment or has a blocked air passage. The adjustment screws have knurled and tapered heads to keep us from messing with them, so I won't be going there any time soon. Besides, if that is not the problem, It would only make matters worse. :censored: Would it help to open up the small holes in the muffler and the baffle plate? If so, how big should they be?

 

[M.D. Vaden]

If that's a newer machine, that's almost remarkable.

Almost all manufacturers put spark arrestor screens somewhere in the muffler or just behind it these days.

I have yet to buy a chainsaw, blower or gas hedge shear in the past 6 years that didn't have one.

That's the first thing I do to them before I even operate them - take the screen out.

Maybe Poulan didn't do it with that one.

Anyhow, it's worth keeping in mind for other machines.

And your probably tried to open that muffler in half - right? Some come apart in halves to reveal a screen.

 

[Alleycat]

I didn't try to open the muffler up. It's built like a tank. The mounting bolts go through tubes that are flanged over the outer case and crimped. The two halves of the body are also crimped. It looks pretty much like an attempt to open it up would destroy it. The inlet port is large enough to see inside and there are no screens visable. I tried to start the engine with the muffler off, with no luck. I guess it needs the back pressure from the muffler.

 

[M.D. Vaden]

Will it run with the muffler off, just to see if it still runs nasty?

 

[Alleycat]

Will it run with the muffler off, just to see if it still runs nasty?

It won't start with or without the muffler.

 

[Kneejerk Bombas]

When diagnosing 2 stroke problems, I use a small squirt bottle with 2 stroke mix in it. Take off the air cleaner, choke open, full throttle, and give one small squirt down the carb throat. This should get the saw to start. If not, consider spark or flooding.
If the cylinder was loose, the base gasket may have been damaged, that could cause big problems, like air leak/lean seize.
If the carb was loose, the gasket could be damaged too, which could cause an air leak or possibly block the impulse hole, which pumps air to the carb for the fuel pump.
Blowers run the magneto off the blower fan. It is possible to have spark, but the timing could be off, if the keyway strips. This could happen if there was a backfire, your shirt tail got sucked up the back of the blower, or maybe if it fell off the roof. If all easier problems leave you scratching your head, you might check that.

 

[antigrassguy]

Mike m PM me

 

[Alleycat]

Running

Finally got it going again. The ring was stuck tight in the pistons groove. Soaked several days in carb cleaner and was able to free it up. Runs like a champ now. I always use fresh gas so wonder what caused this. Thanks to all for suggestions.