Half speed with blower....help

Richard · Apr 20, 2012

Typing on iPad, hate this.

Visiting TN, leaving sun

Stihl backpack blower

Other day, filled with new premium/50:1

Blowing father in laws driveway

Working fine, suddenly, will NOT go beyond 50 percent revs without dying.

Feared bad gas so dumped it, bought more premium

Pulled plug. Plug is LIGHT tan (lean?)

Today, took carb off. Pump 'looks' fine, no obstructions in fuel lines. Fuel filter also looks fine. Actually, looks brand new.

Put new plug in

Idles FINE, goes to low rpms fine. If I hold the throttle, it WILL blubber & die.

Quick pull and will fire right up.

Seems to only be affected above say, 50% rpms or more.

What is weird... It was working FINE, then, suddenly, blubbering, which is why I feared the new gas.

Thoughts???

I'm heading back to Florida on Sunday

J_J · Apr 20, 2012

I used Stihl backpack blowers for many years.

Problems I had was inside tank filter, and blocked screen in the exhaust.

Replace inside filter and remove the exhaust screen or clean the carbon off it.

mostly_gas · Apr 20, 2012

plug color OK. If gas and carb ok start looking for exhaust obstructions like spark arrestor.

Richard · Apr 20, 2012

Spark arrester has been removed, as Long as the spark arrester is defined as the little screen that wrapped around the exhaust.

Could something in ignition cause this?

I'll admit to behind dumbfounded

Richard · Apr 20, 2012

Revelation?

Went back out to fiddle.

Took air cleaner off, started (same issue)

I then took my finger and constricted/plugged the fuel tube (feeding the air intake)

Sucker sprang to life and went to full rpms with trigger pulled.

Does this imply there is a membrane in the carb that controls fuel flow?

Got to keeping it revved with fuel outlet plugged with finger on top. Ran better with fuel plugged by finger than no obstruction, suggesting to me it's getting too much fuel when trigger is pulled. I actually saw some drops of fuel at the orifice.

Guess I'll pull face of carb off and look closer for a rip.

Sound reasonable?

tcartwri · Apr 20, 2012

I just recently went through this with my stihl chainsaw. Put fresh gas in it, and the bugger would not start without pulling my shoulder out. Once running it would not pull to full power. Dismantled the saw, checked everything, put it back together. Same thing. madder than stink at this point.

In frustration I started cranking the low speed jet open until it finally started and idled. I'm going to say it is at least twice the recomended adjustment. Idled the saw and opened the low speed until it four stroked, and then turned it back in until smooth. I adjusted the high speed while under load ( cutting ) Saw runs perfect now. Starts with one pull.

The only conclusion I have is that there is something defferent with the fuel that the saw doesn't like. The fuel here is E15.