Chainsaw won't start

[dogdayz]

Looking for ideas...

My little Jonsered 2138 was running great last fall. The primer bulb was cracked so I replaced it - simple job.
That is all I did, nothing else.

This year the saw simply will not start, not even a cough. It has good spark, fuel is getting in. I have put in fresh fuel, replaced the spark plug but it just won't start.

I am pulling my hair out (not that I have much). My shoulder and back are in pain from pulling that cord (why doesn't someone put an electric start on the saws?):tehe:

[runamok]

Does fuel get to spark plug meaning does it look wet with fuel?Check spark arrestor screen on exhaust for oil build up.Could be a compression problem you can try squirting a teaspoon of motor oil in carburetor air inlet and see if it fires.If this doesn't work pull exhaust off and look for scratches (lines up and down on side of piston.

[Terryl]

I would check the air filter, some have a foam air filter, these types need to be cleaned and in some cases re-oiled for the saw to start.

If it has a foam air cleaner then wash it in hot and soapy water, then dry it, re-oil it with 30W motor oil by putting a few drops on it and squishing it around.

Some small engines like these need just the right air fuel mix to run right, a plugged or totally dry air filter can cause it to not want to start or run too good.

One other possible cause for not starting is no spark, this is hard to test while trying to pull start it, one way to do this is to firmly clamp the saw blade guide in a bench vice, this with the pull start accessible, be sure to allow the saw blade to move freely.

Then a spark tester (from your local auto store, or one like below) will tell you if it's getting spark.

Darken the room (garage) and giver it a pull, but not hard enough to start it, you should see a spark, if your not comfortable doing this,(worried about it starting in the vice) the spark plug can be removed and the spark tested that way.


https://www.amazon.com/Lisle-20610-Inline-Spark-Tester/dp/B0002STSC6

One other possibility is that the fuel jets are plugged, this could be due to fuel evaporating in the carb bowl, the fuel is a mix of gas and 2 stroke oil, the oil will be left behind, this can plug up the jets, this will cause it to not get the right air/fuel mix.

The carb can be cleaned out with a can of spray carb cleaner, you may have to remove the carb and fuel bowl to do this.

And if you are not comfortable doing all this, you could take it in for service.

[dogdayz]

Thanks for the detailed tips.
I have removed the bar while I am testing. I have tried with and without the air filter. I have tried carb cleaner and soaked seafoam in the carb. The compression is good. I removed the plug and grounded it outside the cylinder and it has good spark. Fuel is getting into the cylinder, the plug gets wet. I even tried a shot of ether. It doesn't even cough when I pull the cord. It is a pointless ignition so that's not the problem. The flywheel key is good. The spark arrester is clean. Piston has no scoring, ring isn't broken.

I've done a lot of work on small engines - this one has me stumped. If ya got fuel and spark it should fire.

[Terryl]

It could be the air/fuel ratio, if the jets are plugged or restricted it wont get the right mixture to fire.....The funny this is that it wont run with starting fluid.

As to the air filter is it a wet type?? (foam and needs to be oiled?)

I had a rototiller with a foam filter that needed to be oiled, I pulled my arm off trying to start it, took it to a small engine guy, he pulled the foam air filter, washed it out, re-oiled it and it started right up.(me slapping my head)

The thing with some small 2 stroke engines is the fact that the air filter needs to be in-place and oiled (if required) to run, otherwise the air/fuel mix is wrong.

[Terryl]

One other thing, you said that the primer bulb was cracked and you replaced it.....Take a look into the gas tank, is there a small filter attached to the end of the fuel pickup tube???? One of my saws had a plugged filter, pulled my arm off trying to start it, replaced the filter and it started.

[iq180]

Check your Exhaust to see it's not pluged, down south we have a nasty little wasp that will fill the exhaust with eggs and mud.

[runamok]

OP said spark plug was wet meaning fuel is getting to to spark plug.Op also said spark arrestor screen in exhaust was clean.Compression may be weak test with a teaspoon of motor like I said.Wont hurt a thing.

[iq180]

OP said spark plug was wet meaning fuel is getting to to spark plug.Op also said spark arrestor screen in exhaust was clean.Compression may be weak test with a teaspoon of motor like I said.Wont hurt a thing.

I was not talking about the Exhaust screen, I was talking about the final Exhaust exit port after the screen.

[runamok]

I was not talking about the Exhaust screen, I was talking about the final Exhaust exit port after the screen.





You have to take off exhaust port to check spark arrestor screen if it has one.I am sure the op would have seen a clogged problem.

[dogdayz]

The air filter is a heavy felt material, I guess maybe I can try washing it in a soapy solution.
I'll give the oil in the cylinder test a try.
Yes it has a fuel filter but the fuel is definitely getting through.
The exhaust screen and muffler are clean.

[dogdayz]

Well I am making progress...
I did some more work on it and now it is starting.
If I spray some carb cleaner into the intake it revs up fast and then dies out. If I pump the trigger quickly it will keep running for a few extra seconds but then dies. Sounds like it isn't getting enough fuel. Either something is plugged or maybe it needs a carb rebuild.

[runamok]

If there is to much fuel in the system pull fuel line off carburetor and try starting with full throttle no choke.If it fires or runs reconnect fuel line.Don't let it run no more than a couple seconds with fuel line disconnected.

[Putski]

I'm guessing you need some carb work!

[Terryl]

I've had problems with spider mites building nests up inside the carburetor passages, this blocks the fuel flow, I solved that problem with storing the weed eater's wrapped in plastic bags and duct tape.

Saves a big headache rebuilding and cleaning out the carb in the summer.

You could have something plugging the carb.

[dogdayz]

I'll have to pull the carb and disassemble it for a good cleaning in the next day or two. If that doesn't work then I saw a good price on ebay for a new complete carb that comes with air and fuel filters, fuel lines, primer, plug and gaskets.

[ford guy]

check the vent hole in the gas cap, it may be plugged

[dogdayz]

check the vent hole in the gas cap, it may be plugged

Did that before, thanks.

[dogdayz]

I took the carb apart as much as I could this morning, sprayed it good with cleaner - let it soak. Took out the needles and readjusted.
Didn't help!
Guess I'll order a new carb, if that doesn't work then I will have a Jonsered boat anchor.

[runamok]

The chainsaw should fire even if a carburetor isn't mounted with a little gas mix or ether poured in cylinder.You said it doesn't fire if so it has some other problem.

[dogdayz]

The chainsaw should fire even if a carburetor isn't mounted with a little gas mix or ether poured in cylinder.You said it doesn't fire if so it has some other problem.

See post #12 - It does fire up, just can't keep it running.

[runamok]

If the carb is still on try turning both air and fuel adjustment screws clockwise until they lightly seat then turn them out 2 full turns.Adjust the L side until it idles probably turning L clockwise a little.If it idles try throttling up and adjust H side probably turning clockwise a little until it revs smooth and stays running.If it stays running do not turn H to max rpms because it will run engine to lean on fuel back it off a little..

[dogdayz]

If the carb is still on try turning both air and fuel adjustment screws clockwise until they lightly seat then turn them out 2 full turns.Adjust the L side until it idles probably turning L clockwise a little.If it idles try throttling up and adjust H side probably turning clockwise a little until it revs smooth and stays running.If it stays running do not turn H to max rpms because it will run engine to lean on fuel back it off a little..

I can give your suggestion a try. I did remove the screws when I cleaned the carb. I set them at one turn out. I'll try the two full turns. It's difficult to adjust when I have the saw put back together because I don't have the special knurled tool that is needed. I want to cut slots in the screws so I can use a flat screwdriver. :)

[HubzPub]

I can give your suggestion a try. I did remove the screws when I cleaned the carb. I set them at one turn out. I'll try the two full turns. It's difficult to adjust when I have the saw put back together because I don't have the special knurled tool that is needed. I want to cut slots in the screws so I can use a flat screwdriver. :)

Try an electrical Butt Connector on the knurled screws. If you find one that fits snugly, you can turn with a small screwdriver or needle-nose pliers. It worked for me.

[runamok]

I can give your suggestion a try. I did remove the screws when I cleaned the carb. I set them at one turn out. I'll try the two full turns. It's difficult to adjust when I have the saw put back together because I don't have the special knurled tool that is needed. I want to cut slots in the screws so I can use a flat screwdriver. :)





I have a set of carb adjustment screwdrivers now.But I have used a dremel with a cutting disc and cut slots in adjusters many times.

[Terryl]

I just use a piece of heat shrink tubing, and let it stick out beyond the casing, once adjusted you can leave it or cut it closer.

[dogdayz]

I just use a piece of heat shrink tubing, and let it stick out beyond the casing, once adjusted you can leave it or cut it closer.

Good idea but the screws are too stiff to turn with heat shrink tubing. I'll try and cut slots in them.

I have to wait until the weather cools off - just too dang hot to work on this outside.

[dogdayz]

Just thought I would update this thread in case anybody is interested...

I ordered a new carb from ebay and received it today. I put in the new carb and the saw started in two pulls - music to my ears!

So, I don't know what the issue was but now I am ready to cut wood again.

Thanks to all you guys for trying to help out.

[Putski]

old cheap gas... does it every time if it sits to long!
Glad you got it running!:thumbsup:

[bad1]

Just thought I would update this thread in case anybody is interested...

I ordered a new carb from ebay and received it today. I put in the new carb and the saw started in two pulls - music to my ears!

So, I don't know what the issue was but now I am ready to cut wood again.

Thanks to all you guys for trying to help out.

FYI I work in a small engine shop and we don't rebuild carbs if that is the issue. Parts verses labour, new carb wins most of the time because of shop rate. Most of the time when we clean the carb in the ultrasonic cleaner you have to get it perfect and that rarely happens. So it's a new carb and 15 minutes later it's ready to go back to the customer.

[whooper16]

Check flywheel key.its either that or coil

[dishuser]

Just thought I would update this thread in case anybody is interested...

I ordered a new carb from ebay and received it today. I put in the new carb and the saw started in two pulls - music to my ears!

So, I don't know what the issue was but now I am ready to cut wood again.

Thanks to all you guys for trying to help out.


Check flywheel key.its either that or coil
I will let you figure it out

[jazzman]

After this long I don't blame you lol. OLD thread...