PC Blues

Greetings,

I just got done solving a problem over at the network forum and was surprised to find a small engine forum. Hopefully, I can get lucky and fix this too. I have a Troy Bilt 49cc 20" chainsaw that was purchased new online 2 years ago and has seen only 1 hour of operation.

I have been unable to get it to fire and never was able to get any factory support locally due to the fact that it was bought online. I get spark and have attempted to prime cylinder with starter fluid but can pull til I'm exhausted and not get a cough.

Any help will be greatly appreciated.

dai

did you empty out the fuel and put fresh in at the right mixture ratio

Basementgeek

Just because you see it spark doesn't mean that the plug is firing under compresson.

Have you tried a new spark plug?

BG

MrChooks

Agree with BG - try a new plug - a dud plug is a cerain "no-goer"

BUT next time don't prime the cylinder with starter fluid - try just a "goodly" spray into the air intake - it's very easy to "flood" these little 2 strokes - and once flooded they wont start until the air fuel mix comes back to normal.

So, once you have a new plug installed, on a cold engine, prime the carb, set the choke to full rich and give the air intake a spray with starter fluid and give the "little devil" a few good pulls and it should start.

As soon as the engine starts - reduce the choke gradually back to nil

PC Blues

I'll pick up a new plug in the morning, start with a fresh mix and post outcome.

PC Blues

Well, I followed through with the suggestions but still can't get a burp. The service center where I got the plug thinks the carb needs to be rebuilt. Before going that route, can someone explain how to adjust the carb. The operation manual ignores it, suggesting I contact a authorized repair center.

Basementgeek

Does it have compression ?

Open the choke, open the throttle - give less than a one second squirt of ether and now try it. Even with a bad carb it should try to start assuming the timing has not been changed. I am guess bad coil, dirty connections.

Check out this handy little tester:

http://www.harborfreight.com/cpi/cta...emnumber=93795

BG

vnestohr

It's very odd that you got nothing at all even with directly priming the cylinder with starter fluid. Right there, you made sure that you had something in the cylinder to burn. I'd suspect the spark plug - even if it is firing outside the cylinder. Maybe there's an issue with the spark plug wire that's shorting/opening when the plug is in position. [Check your ground side too]

Also, please confirm that you are getting no signs at all of any combustion - no smoke, smell of smoke, etc. - the other possibility is that the timing is off and you are getting some sort of burn, but just at the wrong time. I would think that some sort of sound would accompany this - maybe not a bang, but a fwoof or something along that line, depending on how much either you used.

PC Blues

I actually have a inline style spark tester from Harbor Freights that gets a lot of use. When hooked up to the chainsaw, it glows like a Christmas tree. I tested the spark plug in another chainsaw and it ran with no issues. I just repeatedly injected starter fluid down the throat of the carb and pulled like hell, no burp, no smell, no heat, no smoke, no nothing.

Tumbleweed36

Is it hard to pull, like does there appear to be compression?

The reason I ask is that some chain saws (can't find anything about this one) have a compression release valve to make pulling them easy and then it closes to start after you pull it. Could this model have that feature and have it stuck open? I am shooting in the dark, but thought I would mention that. That seems to be the only reason it would not fire under the circumstances, but hey, I am certainly not a chain saw expert...do know about Stihl (own those), but not this brand.

vnestohr

Oooo! In your original post you said "have attempted to prime cylinder with starter fluid", and I thought that you were pulling the spark plug out, shooting some starter fluid in the cylinder, then putting the plug back in.

This new understanding gives us a new direction to go in.
Since you are actually putting the starter fluid into the air intake and you have confirmed that you have a good spark - that would mean that the starter fluid isn't making it to the spark.

The two things I can think of are: it could be a stuck reed valve (won't open to let fuel/air in), or your piston isn't moving (no suction).

I would do the following: pull the spark plug out, stick a pencil - eraser end first - (or dowel rod) into the cylinder and slowly crank the 'saw over. The pencil should move in and out. (Depending on how you orient your saw you may need to push a little on the pencil - don't be to hard pushing or cranking, breaking the pencil would be BAD). If it moves in and out your pistion is moving. If the pencil dosn't move, stop right here: you know your problem.

Assuming the pencil moves, the prime suspect becomes the reed valve. It could be varnished over, rusted, etc. I am not advising you to do this: I personally would squirt a little bit of starter fluid directly into the cylinder and quickly put the spark plug back in, hook it up, and try to start the chainsaw. I would cross my fingers that the first bang would jar the reed valve... and that I didn't put too much fluid in and make a bomb...

PC Blues

Initially, I was shooting starter fluid directly into the cylinder but others recommended that I shoot it into the carb intake.

I did the pencil thing and the piston is indeed moving up and down.

Tried the fluid to cylinder step twice but still get no results; spark tested good.

vnestohr

Now, that has me stumped (not to hard to do, actually). Fire needs three things: fuel, spark, and air.

The either is the fuel, should be enough air in the cylinder already... You've tested out the spark plug itself - in another chainsaw. And used an inline spark plug tester in the chainsaw with the trouble, and it shows good.. Even a weak spark should produce some fire..

I don't know much about the spark plug testers, if they can get a false positive or not (I usually just lay the plug itself on the engine and see if there's a spark that way).

Here's one thing that I can think of: the spark plug wire has a short in it. When you use the inline tester, it extends the wire so it dosn't contact the chainsaw body. [Try the starter fluid thing with the inline tester, if you haven't already] When you remove the tester, the wire goes back 'in place' and shorts out again...

After that, I'm out of ideas... sorry...

clowe

I know you said the saw is only a few yrs old. try compression test which should be 100-120 pds any less forget it .If u are getting a spark set carb srew turn all the way in an back out 1&half turn for H'' an 1 turn for L'' saw should try to start.If so continue to adjust from there.

v1_0

I recently had a similar experience with a Toro string trimmer of mine.

I went to start it using the standard procedure (prime, choke-pull-kick, no-choke-pull-run). This time it kicked once, but wouldn't start after that no matter what I did.

Checked spark, had it. Even replaced the spark plug - had better spark. Still wouldn't start.

Shot starter fluid through the carb. No joy.
Pulled (new) spark plug, shot fluid into the cylinder. No joy! That was a big puzzle right there.

Anyway, let it sit overnight - yup, just picked it up how I left it, and it started right up the next day with the standard procedure.

I'm guessing I overdid the priming and flooded it. The flooding prevented it from starting, even with a new spark plug and starting fluid.

That may be what you are running into here. So, drain the gas. Pull the spark plug, spin the motor a couple of times, then put it in a safe place and let it sit for a couple of days. (To "dry out").

When you come back, leave the gas tank empty - shoot a bit of starter fluid into it, put the spark plug back in, and see if it fires up.