Chainsaw cylinder filling up with gas!!!

[bwestbrook]

I have a Stihl chainsaw 028 that just fills up with fuel. Fuel lines are good. Thought it might be tank vent. Cleaned it out good. Still does it just sitting there. Take spark plug out and pull rope and fuel shoots out of exhaust and spark plug hole. Any help would be appreciated.

 

[DaveTN]

Sounds like the carburetor needle is stuck open. Could be some dirt or something keeping it from seating. Wouldn't hurt to take the carburetor off , disassemble and clean it.

 

[bwestbrook]

I knew that would be it on a 4 cycle but just never had it happen on a 2 cycle. Thanks will try that out tomorrow.

 

[bwestbrook]

Well took carb off and cleaned. Needle is seating properly. But noticed that while carb was off fuel was coming out of the fuel line coming from the tank. I opened the fuel cap and fuel went down. This is got to have something to do with the tank vent and the tank building up pressure. The only thing is that it is about room temp. Shouldn't build up that fast if at all.

 

[tkin]

Well took carb off and cleaned. Needle is seating properly. But noticed that while carb was off fuel was coming out of the fuel line coming from the tank. I opened the fuel cap and fuel went down. This is got to have something to do with the tank vent and the tank building up pressure. The only thing is that it is about room temp. Shouldn't build up that fast if at all.

Thanks for the last bit of information....I had the same problem and it saved me some time. It does not need to be hot for the fuel to siphon up because the capillary effect....I seen fuel bubbling up the gas supply hose until I loosened the gas cap.

 

[ILENGINE]

Fuel coming out of the fuel line on a two stroke engine is normal. Most have tank vents but is a one way valve in most cases, so the tank will be pressurized. Most common problem with gas leaking is dirt under the needle valve tip preventing it from sealing or dirt will build up under the metering diaphragm cover preventing it from returning to the rest position and closing the needle valve.

 

[snaquebite]

I have a Stihl chainsaw 028 that just fills up with fuel. Fuel lines are good. Thought it might be tank vent. Cleaned it out good. Still does it just sitting there. Take spark plug out and pull rope and fuel shoots out of exhaust and spark plug hole. Any help would be appreciated.

I've got the same problem on a Craftsman. Have cleaned and rebuilt the carb including needle valve. Problem continues.

 

[primerbulb120]

I just had this same problem on a Troy-Bilt blower. It turned out that I had installed the wrong fuel pump diaphragm, allowing gas to enter the crankcase via the pulse hole. I installed the correct diaphragm and the problem went away.

 

[snaquebite]

I just had this same problem on a Troy-Bilt blower. It turned out that I had installed the wrong fuel pump diaphragm, allowing gas to enter the crankcase via the pulse hole. I installed the correct diaphragm and the problem went away.

I matched all the original gaskets, diaphragms etc with the old ones since the repair kit comes with more than needed. I could have possibly screwed up but don't think so...will do a double check. Thanks.

 

[snaquebite]

diaphragms are correct...