Stihl 039 problem

[jerkputter123]

I got a Stihl 039 that will that starts on third pull. Runs great. Used about 1/2 tank gas cut it off , go back after about 15 minutes and it won't crank back. I removed the carburetor, clean it and it will start again. I have noticed when I remove the carburetor a stream of gas shoots out of line to tank about 2 foot , seems like a lots of pressure. Is this a vent problem ? this vent has 2 springs in it with a screw in the end which looks like it would block it. Should I just order a new vent ? Any suggestions on this welcomed

[bgsengine]

I have noticed when I remove the carburetor a stream of gas shoots out of line to tank about 2 foot

perfectly normal especially if unit has been running just before, or sitting in hotter environment.. tank vent should hold 2-3 PSI pressure and zero vacuum.

[jerkputter123]

I have noticed when I remove the carburetor a stream of gas shoots out of line to tank about 2 foot

perfectly normal especially if unit has been running just before, or sitting in hotter environment.. tank vent should hold 2-3 PSI pressure and zero vacuum.

Any idea on why it won't start back ? after I use it and then let it sit for a while ? One time I let it sit for two days and it still would not start back after I shut it off. I take the carburetor apart, put it back together and it cranks

[bgsengine]

kinda sounds like maybe your metering needle sticking, possibly, or a kink or crack in fuel line that gets re-sealed when installing the line back to carb... do you happen to notice any fine lint or debris in the carburetor's inner filter screen? if so, then new fuel lines and filter are in order.

[KE4AVB]

Also pressure test the inlet side of the carburetor should hold about 6 psi (5.8 psi per service manual) without leak down. Plus metering diaphragm must not be stiff.

[jerkputter123]

I will order a carb kit and see how it goes. I have had this saw for many years and never put a diaphragm in it. I will let you know. A big thanks again.

[jerkputter123]

Got the carb kit installed. He said he can only get it to start by removing the air filter. This is actually my cousins saw and I am just relating the message he tells me. He said when it is running a small mist of fuel is coming out of carb . I will try and take a look at it today. Maybe setting are wrong or intake has a hole in it. Also I guess the muffler could be stopped up but I will know more later today. Thanks for any help.

[KE4AVB]

Standard setting:

H = High speed adjusting screw backed off 1 full turn
L = Low speed adjusting screw backed off 1 full turn

If the carburetor has to be adjusted from scratch, first carry out the
standard setting to obtain a starting point for fine tuning.
If no tachometer is available, do not turn the high speed adjusting screw
beyond the standard setting to make the mixture leaner.

From the SM

[jerkputter123]

He said he removed the carburetor, took it apart it down again and found the diaphragm installed wrong after looking at a picture of the way it was supposed to be installed. . It cranks perfect now he tells me.