Stihl 200T stops running after a few minutes

[capejwc]

Think I might have a coil issue, but here is what is happening. After saw warms up for a minute or two, I have worked on tuning the carb using a tach. After 4-5 minutes, the saw just acts like it is running out of fuel. So far, I have tried two different new carbs, installed new impulse line, checked the fuel hoses for cracks, checked the fuel filter, intake boot and made sure the tank vent is clear. Also checked the coil to flywheel gap and spark plug. Any suggestions on what I seem to be missing?

 

[lone wolf]

Think I might have a coil issue, but here is what is happening. After saw warms up for a minute or two, I have worked on tuning the carb using a tach. After 4-5 minutes, the saw just acts like it is running out of fuel. So far, I have tried two different new carbs, installed new impulse line, checked the fuel hoses for cracks, checked the fuel filter, intake boot and made sure the tank vent is clear. Also checked the coil to flywheel gap and spark plug. Any suggestions on what I seem to be missing?

OEM carbs I hope? Sounds like the coil. Make sure the tank vent is working, or remove it and try once more before you buy a coil.

 

[capejwc]

Aftermarket carbs. OEM tank vent that has clear flow when applying vacuum, but stops when blowing. Simple test with slight pressure and vacuum using my mouth. Will give it a try tomorrow with the tank vent removed.
How do the aftermarket tank vents compare to the OEM tank vents?

 

[lone wolf]

Aftermarket carbs. OEM tank vent that has clear flow when applying vacuum, but stops when blowing. Simple test with slight pressure and vacuum using my mouth. Will give it a try tomorrow with the tank vent removed.
How do the aftermarket tank vents compare to the OEM tank vents?

Tank vents either work or don't . Since it runs OK then craps out in 5 minutes, I say coil prob! Get an OEM coil. Look for spark when it dies in 5 minutes.

 

[Tnjind]

My sachs did exactly same, rebuilt carb, fuel line....it was spark plug.

 

[HavinFun]

Check out what Taryl finds is the fueling issue on this Dolmar. He’s a really good mechanic, and I learn from watching his videos. Sorry, no spoiler, gotta watch it.

 

[capejwc]

My sachs did exactly same, rebuilt carb, fuel line....it was spark plug.

How long did it run before cutting out? This saw runs 3-5 minutes and then dies like it is out of fuel. I have spare spark plugs, so will give that a try too, but really suspect the coil is shorting out when it gets hot.

 

[Tnjind]

Sachs would run for 1-2 cuts then die just like shutting off the kill switch..

 

[Tnjind]

I have never seen that before. The saw has been running great since new plug. The crazy part was that it ran great with the old plug too until it would suddenly die. Rest it for a couple of minutes and it would fire up and run for another cut or two. I thought the coil was get hot since it wasn't fuel. I couldn't find a c oil for it so it almost got junked..

 

[capejwc]

Still a mystery on the Stihl 200T. Here is what I did.
Replaced the existing spark plug with a new plug and removed the tank vent (It was the OEM one). Started the saw and ran for 10 minutes with just a bit of saw work since it started raining. Ran fine all 10 minutes.

Replaced the new spark plug with the old one and left the tank vent out. Ran for 10 minutes again, but did not put in the wood since it was raining pretty hard. Ran just fine for 10 minutes. Ran the rpm up and down several times. A little inconsistent on the idle, but throttle response was good. Did not tach the idle or the upper RPM.

Replaced the OEM tank vent after taking it apart and blowing out the jets and passageway with some light air pressure. Replaced the tank vent and ran again for 10 minutes with no problem. Did the 'drop' test several times and the saw still continued to run just fine.

Not sure what solved the problem, but leaning to a sticky tank vent. Will get it back to neighbor who owns a large tree service/logging company and he will give it a good workout. He does not have much patience with a saw that doesn't run well. Don't blame him since time is money.

If it starts having the same issue again, I think I will start with a new tank vent first.

 

[stihltech]

Which vent do you have? There are 2 versions. Actually 3 if you count the one that usually got replaced.

 

[Wood Doctor]

It is rare that the spark plug caused this problem. However, it can happen. I usually replace the plug first and then go on from there. It's a simple fix, but seldom does a new plug fix anything. Usually, as Lone Wolf suggested, the coil will fail first. I have replaced several failed coils on Stihl top handle saws.