Stihl Starting Porblems

[gravity316]

Hello All,
I wanted to ask for some advise on starting my MS390.
It is around a year old and I wanted to see if I can fix it before it goes back to the dealer. It ran fine all winter/sping. Now in the summer it will start fine when the saw is cold, but if the saw is warm it does not want to idle for long or accellerate. Once it is running it idles fine and performs like normal. I cleaned the air filter and checked the plug. I cleaned the carb and checked the tank vent. Now I am not sure what to do.:censored:
Any thoughts are appreciated.
Thanks

 

[2000ssm6]

Sounds like it needs a carb adjustment. If you haven't had any help by the time I get home from work, I'll send a service manual to help explain.

 

[nmurph]

how long did this saw sit? i have left my 310 with the same fuel all winter and not had problems starting it. however, many people seem to have more problems with bad fuel in the tank.

how did you clean the carb? did you pull it off? take it apart? is everything back together in the right order? did any gaskets get messed up? did you clean the passages? with compressed air or with carb cleaner?

if you are sure the carb is ok, i would check the fuel line. they seem to be the culprit in starting/runing issues on the series of saw. on a 2YO saw it should not be a problem, but it is a cheap part (~$10) to replace.

PM (top, right corner) me your email address and i will send you a service manual.

 

[gravity316]

Thanks for the replys.
I mixed the gas around 1 month ago, stihl oil with fresh gas from store.
I got the carb put back togther right. I am pretty sure, because I was careful and it runs the same as before. No change. I have a manual I bought off of Ebay, but could not find my exact issue. Starts fine cold, but trouble starting warm, but once running performs fine. I did not think it would be the fuel line since the problem is only when start warm. I was a little leary of adjusting the carb. If I follow the manual I probably cannot screw it up too bad right?:monkey:

Thanks for everyones help.

 

[huskystihl]

Unless something was lurking around in your can or you just had some really realley bad gas you shouldn't have to clean a carb on a one year old saw. In fact I can't remember the last time I had to. My five year old blower is maybe ready for a carb kit. I think you just need an adjustment, if your not familiar take it to the dealer.

 

[gravity316]

No chance in the gas mixup, unless I am bipolar?
I do not let my buddies monkey with my toys. Learned the hard way.

Pulled the muffler and the cylinder wall looks fine, except the appearance of a ring going around the diameter of the cylinder at the top of the intake ports. Is this normal?

I will trying readjusting the L setting on the carb. Figure H is ok since it runs OK when wound out.

 

[Bill.A.Bong]

When its warm I assume you start it on 'Run' and no choke? Not sure what you mean when you say - does not idle long or accelerate? What does it do when you hit the throttle - stall?

 

[wmswilson1]

Sounds like heat is transferring from your cylinder onto the carb causing the gas to vaporize thus not allowing enough gas to enter engine. Before screwing around with your mixture screws or buying new gas run the saw then once its hot turn it off and feel the carb if its hot thats your problem and you will have to rig so kind of insulator between the carb and cylinder.

Matthew

 

[Saw Dr.]

Sounds like heat is transferring from your cylinder onto the carb causing the gas to vaporize thus not allowing enough gas to enter engine. Before screwing around with your mixture screws or buying new gas run the saw then once its hot turn it off and feel the carb if its hot thats your problem and you will have to rig so kind of insulator between the carb and cylinder.

Matthew

The carb is isolated from the cylinder by a rubber intake on that saw, so I doubt that is the problem. You should not have to rig anything to anything on a $500 saw. Before screwing around feeling for hot carburetors, check the fuel line.



Are you using a metal fuel can? I have seen rusty gas clog more than one inlet screen on these saws.

 

[litefoot]

If it's less than a year old, just take it back to the dealer. Let him fix it.

 

[wmswilson1]

The carb is isolated from the cylinder by a rubber intake on that saw, so I doubt that is the problem. You should not have to rig anything to anything on a $500 saw. Before screwing around feeling for hot carburetors, check the fuel line.



Are you using a metal fuel can? I have seen rusty gas clog more than one inlet screen on these saws.

:agree2:

 

[gravity316]

No metal gas cans here.
Gas line and intake filter looks fine.
Adjusted the carb, but with the limiting caps you cannot really go to far.

Back to the dealer it goes.

Thanks for everyones help.