BG85 stalling

[QuattroKev]

Hi, new to the forum, first post...

 

Having some issues with a Stihl BG85 blower I'm repairing for a friend.

 

Problem is: engine will always start, but will immediately die with anything over quarter throttle, no matter how slowly you feather it up.

 

So far I have rebuilt and cleaned the carb. Replaced all carb diaphragms and gaskets, replaced leaky fuel line, replaced the spark plug. Checked and cleaned fuel and air filters and tank breather.

 

Checked for the exhaust filter being clogged, which is not present and free flowing.

 

Problem remains.

 

Discussion on Yank forums points to a problem with the ignition coil.

 

Any suggestions before I shell out for a new one?

 

Cheers

 

Kev

[QuattroKev]

Just realised this is in the wrong place, better suited to Maintenance section

 

apologies

[spudulike]

Check the plastic inlet manifold is the right way round, it has an impulse hole in it and must allign with the cylinder and carb properly - it isnt symetrical although it rits both ways round.

 

Other than that, unscrew the H screw and get some carb cleaner down the hole and then try it again. It sounds like high speed fuel starvation. worth checking the fuel line and filter as well as the fuel tank breather.

[QuattroKev]

Re seated the manifold. Still no change.

 

all filters and breathers are ok, fuel lines changed, diaprahms changed, spark plug changed.

 

Stumped...

[spudulike]

Re seated the manifold. Still no change.

 

all filters and breathers are ok, fuel lines changed, diaprahms changed, spark plug changed.

 

Stumped...

 

So what happens if you put the H screw on 2 or three turns out? You most likely have an issue with the high speed part of the carb. Did the diaphragm spacer go between the diaphragm and the carb body - it must be that way round.

 

It is possibly a blocked H speed check valve so take the H speed screw out of the carb and get some solvent and WD40 down it and try again.