how did this happen to my 7900?

[Mr. Obvious]

Pulled my saws out today to dump out the fuel and refill with fresh fuel and stabilizer for the winter. My 3 year old new never used 7900 powerhead had only a partial tank and It was full when I filled it last fall.

So with the new fuel I start to pull it and notice something misting out the right side by the AV spring. The fan is spitting out what looks like fuel vapor out from the cylinder fins. Get it started and it smokes like a banshee out the muffler. Looks like a smoke machine. Also black oil (not bar oil) running out the front from under the muffler.

After a minute or two the smoke clears up. Must have been mix oil running out the front although I use Mobil 1 and this oil was black.

Did the fuel get pushed into the cylinder through the carb some how?

Did not have this problem in the past with this or any other saws.

 

[Sethro]

Sounds like it was flooded and the fuel you saw coming of the flywheel likely came out of the compression release and dripping on to the flywheel .

 

[rupedoggy]

Why did you fill a tank on a saw you were not going to use?

 

[E&R_firewood]

my Makita dcs 6401 does that once in a while after it has sat with fuel in the tank . . . spitting fuel out of the comp. release and smoking like hell, for a few minutes after starting. never acts up when i'm responsible and run it dry or avoid storing the saw with mix in the tank.

 

[roncoinc]

I have had some STRANGE stuff happen to anything i have that has a gas tank..
i store stuff outside,in the barn,in the shed,in a metal building etc..
ever seen a full container of gas expand and pop off the vent cover ??
heat,cold,etc does strange thing when a container has gas in it.
if you had a full tank probly expansion with not enuf venting for the expansion rate pushed the fuel out..
a saw "sucks" in gas,,they not used to having it "pushed" in so it could be the cause of your concern..
now with so much gas powered equipment i dont use that often i am draining the gas and running them dry..then no more bad gas,sludge,varnish,etc.. problems.....use the gas in my splitter or lawn tractor.
oh yeh,,same with string trimmers,,happens with them also..

 

[Hddnis]

It is clearly beyond repair and you should send the saw to me. I'll be doing you a favor by letting you cover the shipping.


:greenchainsaw:



Mr. HE

 

[MCW]

May be totally unrelated but always pays to check your tank breather. I actually had my older model 7900 tank split the other week as pressure built up and wasn't released due to a blocked breather. Warmer weather didn't help and next time the tank "hisses" when I undo the fuel cap to fill up I'll take more notice It split by the handle at the bottom. The tank join didn't look real flash from the factory but a mate plastic welded it up a treat.
Matt