Dead MS361

[HandLogger]

We have a dead MS361 that hasn't been run for several weeks. My first instinct was bad fuel, but our other saws -- which have also been in storage -- use the exact same fuel mixture: and they're running fine.

Thinking that it might simply be a flooding issue -- something that has affected this saw in the past -- I let it sit for a several hours. Unfortunately, that didn't work this time around.

Next, I swapped the plug with one from a known good MS660. Result: the 660 runs fine and the 361 is still dead (not even a slight sputter while being cranked). As the plug(s) that were installed in the 361 come out wet, I then suspected the ignition. After grounding the plug to the cylinder fins, I pulled on the cord and, yes, I see a white spark arcing across the gap between the electrodes.

In short, the lack of a sputter (or even a pop) has me scratching my head. Is it possible that the ignition isn't providing enough voltage? I'm asking because, although there is clearly a spark present during cranking, it appears to be a bit on the weak side. In other words, I've seen hotter/stronger looking sparks.

I'm no saw repair tech, either, so I'd be happy to read any productive thoughts on what we might try next. This particular saw has traditionally been the hardest to start, but it has also been the best all-around operator we own as well.

NOTE: This saw was running fine before it was stored for the hardest part of the winter.

Thanks for your time …

 

[buzz sawyer]

Have you tried blowing out the cylinder and priming with fresh mix, then install the plug and trying to start - just to ensure there is fresh mix in the cyl.?
If you have good spark, compression, and fuel, the only other thing I can think of is timing.

 

[SawTroll]

.... Is it possible that the ignition isn't providing enough voltage? I'm asking because, although there is clearly a spark present during cranking, it appears to be a bit on the weak side. In other words, I've seen hotter/stronger looking sparks. ….

It could well be that the spark is too weak.

 

[redfin]

Do you have good compression. I have a saw that started and ran fine before I tore it down to do a good clean and carb rebuild. Wouldn't fire after rebuild. It needed a ring and cylinder cleaned up.

Very odd.

 

[R/C Pilot]

A little fuel down through the carb will let you know if its lacking fuel. If it is flooded leave it on fast idle no choke and crank it until it clears. I've seen 361's that took a lot to prime up after setting. Good luck.

 

[lone wolf]

The spark should be blue not white, try in dark. Next thing is check the compression with a gauge and or pull the muffler off and look the piston and rings. If your compression is good and the piston and rings are good you have a carb problem or air leak.

 

[jdhacker]

First just spray a little fuel in the carb with the saw on fast idle. I had a brand new saw with about 1 gallon of run time, I was running the saw, shut it down to refuel. And would not start back, but not even sputter. The next day it started ran a tank of gas out. Would not start back, it was a bad coil.

 

[HandLogger]

Instead of chancing it with [what might be] bad fuel, I simply shot a short burst of starting fluid through the carb's butterfly and, once again, not even a weak pop.

Considering that we own and operate several saws, a compression tester is in order. When it comes to tools, I don't mind investing in high quality (within rational reason).
Any recommendations on a good, durable compression gage would be greatly appreciated.

 

[kyle.kipple]

Dont use starting fluid. Just use a splash of mix. Snap-on seems to be a good name that gets tossed often when testers are in discussion.

 

[zogger]

Is the plug still wet? If so, try removing plug, drain any old mix in it out, turn it upside down, crank until no more fuel comes out, then let it sit and air out. You could just be reflooding it all the time.

If something is flooded, and there's fuel in the tank, you will just keep flooding it if you keep yanking on the starter cord. Just letting it sit all corked up, the excess fuel can't evaporate out very easily.

 

[fordf150]

A good spark checker might also be in order. Get the kind that go inline between the plug and coil wire and look like a light bulb in the middle. They can be picked up at local parts store for $10 or so. The spark checkers with just an air gap work but are harder to see.

 

[z71mike]

What other saws ya got? Maybe a coil swap to see if that's the problem.

 

[HandLogger]

The spark tester sounds like a good diagnostic tool to have around, as well, fordf150.

We have an MS660 and an MS200T on site at this time. Are either of those equipped with a suitable coil for a swap, z71mike?
As I mentioned before -- I'm no Stihl saw tech.

Thanks for your time ...

 

[Rookie1]

If its flooded bad pull plug and turn saw upside down. You may have to roll the engine over a few times to let the gas work its way through the transfers. Then leave it sit for a while and try again.
There are secret little German pixies in the coil to change the timing when the saws being started and when its running. It is possible that one of those guys isnt doing his job properly.

 

[z71mike]

We have an MS660 and an MS200T on site at this time. Are either of those equipped with a suitable coil for a swap, z71mike?

No, unfortunately I don't believe so. Pretty sure the 660 coil won't mount up in the same holes.

Not sure about the 200T though. I've never had one of those coils in hand. Hopefully someone a little more knowledgeable than myself can answer that.

What I will say though, it's not that difficult to pull the starter off and have a look at the different coils. Do some measurements and see if they're similar in mounting bosses. Granted, different coils work with different flywheels, so even if you got something to work, I wouldn't leave it in. But for testing, I'd slap anything in that would fit, just to see if it sparks better than the old coil in the 361.

 

[AKDoug]

Before chasing all of this down, simply pull the muffler and take a look inside the cylinder. You will know immediately if you have an issue in that department.

 

[HandLogger]

Bruce, Zogger and Rookie1 must all be MS361 owners because, as it turned out, it was the worst flooding issue I've ever seen.

In the hopes that this thread will someday help out a fellow MS361 owner, here's how it went:

As we own and manage forest land on the side of a mountain in New England, things slow way down for us in the heart of the winter. As I was told that the premix oil we're presently using contains fuel stabilizer, I didn't bother to "winterize" our saws when we locked them up for the bitter cold weeks. The wisdom of this is obviously debatable, but the point is that our saws sat in a storage trailer for about 6 to 7 weeks without being worked. When the weather began to stabilize again, I opened up said trailer and tested the saws contained therein. The only saw that wouldn't start was the MS361; hence, the original post in this thread.

While waiting for the delivery of an order from Jacks Small Engines, which included several new NGK BPMR7A (4626) spark plugs, I put the saw in question in a heated garage. After receiving the order, I removed the used plug from the saw, tucked the coil/plug lead safely out of the way, pressed the decompression valve and began pulling the starter cord (with the ignition switch set to fast idle). After about eight tugs, I turned the saw upside down and blew the cylinder out with compressed air (at low pressure).

After installing a new plug, I reinstalled the air filter (which had been previously cleaned) and the filter cover. With the saw in its normal operating trim, I placed the ignition switch in the cold start/choke position and, once again, began pulling the starter cord. As is its normal pattern, the 361 burped on the third pull, so I lifted the ignition switch one notch (to fast idle) and it started on the second tug. After squeezing the throttle trigger to set the ignition switch to the normal idle position, I ran the saw until the smoke it was pumping out cleared. After that, the saw's engine smoothed out and, most importantly, all seems to be back to normal.

Our MS361 has always been prone to more starting issues than any of our other Stihl saws. It is also our best all-around saw, so the occasional starting trouble has usually been worth the wait. In the end, I would say that it's in your best interest to listen closely when cold starting an MS361 because, if you miss that first burp and leave the ignition switch in the cold start position, you're very likely to flood your saw and ... as someone wiser than myself pointed out … "You could just be reflooding it all the time. If something is flooded, and there's fuel in the tank, you will just keep flooding it if you keep yanking on the starter cord. Just letting it sit all corked up, the excess fuel can't evaporate out very easily." I would say that this is exactly what happened to us.

Thanks to all who posted to this thread. I hope it helps someone else out down the road.

 

[windthrown]

For one thing, NEVER USE an ether type 4-Stroke STARTING FLUID IN A 2-Stroke! That is a good way to score the engine because it does not have any lube in it. Second...

Now that you are aware of it, the 361 is notorious for flooding. I have posted this many times before here: the LA fire department put zip ties on the 361 decomp buttons so that they are not used when starting them. Reason being that when a 361 is cold and the decomp button is set, you do not hear the pop or rumble that means you need to move the lever to fast idle from the full choke position. For that reason it is best to leave the decomp up when starting a cold 361. I only use the decomps for starting my 361s when they are warm when they do not need full choke.

 

[scallywag]

For one thing, NEVER USE an ether type 4-Stroke STARTING FLUID IN A 2-Stroke! That is a good way to score the engine because it does not have any lube in it. Second...

Now that you are aware of it, the 361 is notorious for flooding. I have posted this many times before here: the LA fire department put zip ties on the 361 decomp buttons so that they are not used when starting them. Reason being that when a 361 is cold and the decomp button is set, you do not hear the pop or rumble that means you need to move the lever to fast idle from the full choke position. For that reason it is best to leave the decomp up when starting a cold 361. I only use the decomps for starting my 361s when they are warm when they do not need full choke.

Thanks for the heads up!!... I have a 361 with about 20 hours on it, that saw never starts easy first up! I'll give it go without the decomp next time!

 

[SawTroll]

..... In the end, I would say that it's in your best interest to listen closely when cold starting an MS361 because, if you miss that first burp and leave the ignition switch in the cold start position, you're very likely to flood your saw and ... .....

Yes, definately!