BG 86 fuel issues

chris989

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Hello all,
Seems like all my Sthil equipement fuel lines and vent are failing near the same time due to age. All the fuel lines are soft and collapsing.

I replaced the vent, fuel line and primer bulb and on this blower it barely primes. It will prime fuel and start but the bulb never get remotely full. (wants to stall whit choke off,,,starving of fuel) The primer bulb pressurizes the tank and fuel freely flow back to the carb via the hose. I disassembled the carb and blew out every passage but when assmebled i feel the gas struggles to reach the jet/bulb.

What am i missing on this unit. It has always run flawless until the fuel line just turned to mush.

Thoughts?
Chris
 

sgkent

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if it is a zama carb the thin diaphragm gasket has flaps that double as a check valve for the fuel. If they have warped, which they seem to do annually when they are emerged in ethanol fuel, the carb won't pull fuel. The rebuild kits are almost as much as a new carb. I buy a carb and set the old one aside until I can find a rebuild kit someone is selling inexpensively then rebuild the old one to keep around next time it fails. Draining the fuel out and running dry seems to help them last three to five years - if it is a zama carb or that basic design. All my equipment that has that carb or design goes thru this - edger, tiller, blower etc..
 

StarTech

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You should never use forced air on these cubes. On top the those primer bases do tend to go bad. Now the carburetor rebuild gasket set is Zama RB-155 and it is available in aftermarket, You won't be able to get the kit from Zama due to Stihl inference.
 

bertsmobile1

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And every time the carb comes apart it should get new diaphragms & gaskets as it is near impossible to get a proper seal using old gaskets .
It is not necessary for the purge bulb to be 100% full of fuel as it is on the exit side of the carb .
There is a small filter inside the carb which does get blocked from time to time, particularly if you have a felt filter in the tank .
slide the carb off the engine but leave the fuel lines connected
Turn the carb sideways and blow compressed air through the venturi
If it is clean inside a solid flow of fuel vapour will flow out the end
 

chris989

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I ordered a new carb,, haven't had a chance to try it out but for ~25$ it beats wasting more time on the OE.
 

bertsmobile1

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At $25 that carb has come from evilpay or ammozone
In which case there is about a 24% chance of it being both the correct carb and QC passed
The aftermarket carbs I fit that are guaranteed to fit & work properly are more than that wholesale and that is before tax & my mark up.
 

StarTech

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Yes the OEM is about 3x the price but the there two things good here. One is that get a guaranteed good carburetor. Two your help the locals out and not some stranger that getting rich off selling junk.

On top of that I personally had terrible luck with after markets that I have tried. I even got one cube that was supposedly fully adjustable that the mixture screw ports where never completely drilled through so it was not adjustable and the vendor refuse to take it back. I lost that money and still ended up buying the OEM carburetor.
 

tree monkey 52

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Hello all,
Seems like all my Sthil equipement fuel lines and vent are failing near the same time due to age. All the fuel lines are soft and collapsing.

I replaced the vent, fuel line and primer bulb and on this blower it barely primes. It will prime fuel and start but the bulb never get remotely full. (wants to stall whit choke off,,,starving of fuel) The primer bulb pressurizes the tank and fuel freely flow back to the carb via the hose. I disassembled the carb and blew out every passage but when assmebled i feel the gas struggles to reach the jet/bulb.

What am i missing on this unit. It has always run flawless until the fuel line just turned to mush.

Thoughts?
Chris
Try a better grade of fuel line .it might make a difference .
 
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