Stihl FS200 keeps stalling, running erractic

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bill.g

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An older brushcutter/trimmer that kept stalling out last year. Dismantled the carb & cleaned with ultrasonic & that did the trick.
When using this year all was good but just recently it has started to run erratic & die.
Any ideas here? I can't see how it could be the carb again, I always mix premium grade fuel. I will check the muffler, but after that I'm at wits end.
Thanks.
 
EngineMan

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What about the crankcase seals.....
 
EngineMan

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By doing a leak down test.
 
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bill.g

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EngineMan said:
By doing a leak down test.
Click to expand...


Ok...I’m well aquainted on how to do thaton autos & motorcycles, but not on a 2 stroke. Care to explainin detail, please & thanks.?
 
EngineMan

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The crankcase can be checked thoroughly for leaks with the carburetor and crankcase tester and the vacuum pump, which will be in the service manual for that machine.
 
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bertsmobile1

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Lots of videos out there but Joe pace ( ex Husqvarna Service School ) probably has the best.
https://www.youtube.com/user/PACEequipment
If nothing else note the order he tests things, starts with the tank & cap then goes to the crank and finally looks at the carb.
Way too many just rip the carb off and end up doing more damage to the carb that was not a problem in the first place.

While symptoms can suggest where a problem might be, a systematic approach, suspecting everything till proved good works wonders.

A hand held needs to run with a pressurised fuel tank.
Leaking tanks are far more common than clogged carbs or buggered diaphragms.
Further more if a carb is dissasembled the gaskets should always be replaced as when new they are soft & compliant so they make a good seal.
Once they have been on for a while , they compress and go hard
 
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The Specialist

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bill.g said:
An older brushcutter/trimmer that kept stalling out last year. Dismantled the carb & cleaned with ultrasonic & that did the trick.
When using this year all was good but just recently it has started to run erratic & die.
Any ideas here? I can't see how it could be the carb again, I always mix premium grade fuel. I will check the muffler, but after that I'm at wits end.
Thanks.
Click to expand...

The most common thing missed is the fuel filter. It is probably blocked. Get a new fuel filter. Part number 0000 350 3502. When you get the old one out and put in the new one, try and blow into your old fuel filter. I am sure that you will find that it is blocked. I do agree with the other guy on here when he states that it is a pressurized system. It is from the Gas Cap to the spark plug. The carb is just a pressure control device. If the fuel filter is blocked, fuel is not getting through to the carb.

The one thing to check before you do anything, remove the exhaust and look for score marks on the piston. If you have "barcodes" on the piston, the engine is blown and needs to be rebuilt.
 
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bertsmobile1

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The Specialist said:
The most common thing missed is the fuel filter. It is probably blocked. Get a new fuel filter. Part number 0000 350 3502. When you get the old one out and put in the new one, try and blow into your old fuel filter. I am sure that you will find that it is blocked. I do agree with the other guy on here when he states that it is a pressurized system. It is from the Gas Cap to the spark plug. The carb is just a pressure control device. If the fuel filter is blocked, fuel is not getting through to the carb.

The one thing to check before you do anything, remove the exhaust and look for score marks on the piston. If you have "barcodes" on the piston, the engine is blown and needs to be rebuilt.
Click to expand...

Prepare yourself for the onslaught.
Very few seem to understand that the fuel system is pressurised and seem to think that the fuel pump is doing all the work moving fuel around.
I copped a lot of flack the first time I was silly enough to state it.
 
Boobala

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Bill, don't forget to check the fuel hose from the tank filter to outlet "grommet" or "connector" sometimes an oversight...... my FS-90 drove me crazy because mine was collapsed, something I overlooked.
 
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