Hot gas?

[mrcaptainbob]

It was in the mid seventies today. (Hot for Michigan!!) The sun was out, 60% or so humidity. The normally super well running MS310 was giving me fits. Hard re-starting, sometimes refused to stay running. Restarted 8,9 sometimes more, times. Finally started it with the chain brake off and finger lightly on the throttle. None of this is good. At one point I wanted to gas up even though it did not need it. I was amazed at the tank pressure and the amount of foaming/boiling in the fuel tank. It was about 1/4, maybe 1/3 fuel. Is the saw running hot? Is that possibly causing vapor lock?

[tyb525]

Is your cap vent working? Sounds like vapor lock to me.

[mrcaptainbob]

Don't know. How would I check that? I suspect you may be right. There was a LOT of tank pressure when I opened it.

[mrcaptainbob]

HEY! I just thought of something! (New to me!!) The darned oiler quit working, too. (the other post on MS oiler...) could that cap be plugged and keep the oiler from pumping???

[tyb525]

I can't tell you a good way to check it, but the fact that it is holding a lot of pressure is a good indicator in my opinion.

It could be the same situation with your oil cap too.

[mrcaptainbob]

Hmmmm..I'll investigate that tomorrow. Maybe I can open it with the air hose. Thanks for the thoughts on this.

[tlandrum]

Is your cap vent working? Sounds like vapor lock to me.

i believe that saw does not vent thru the cap it has an actual tank vent.the tank builds pressure as it should but it should not create a vaccum. it sounds to me like you need to give your low needle a little turn out and the problem will be solved

[mrcaptainbob]

I will look into turning out the low end needle maybe a 1/8 turn,tlandrum.

[UN Hooker]

    I think your first sentence in your first post is the clue to your problem - - 70+ degrees.
  You most likely have gas in it that was blended for winter use -- 30 deg. or less.
  Try mixing some fresh gas from a busy station, by now they should be selling gas blended for warmer   
   temps.
                 UN

[ladylake]

Did your tank have pressure or vacume, vacume would make the fuel boil easy and cause running problems.   Steve

[mrcaptainbob]

I have a stack of wood 12' x 18' x 6' tall since mid-January. It's definately not old gas! The tank actually is pressurized, as it spit the gas. But....this is strange...as in the other post regarding the oil pump, now that it's working, the saw is actually running much smoother. No spitting/sputtering and starts so much easier! Too weird.