Small Engines (Lawn Mowers, etc.): Stihl FS80 Carb., zama carburetor, spring hinge

Question
Hi Paul,
I am working on a Stihl FS80 trimmer and I am having carburetor problems. To start with the carburetor would not prime up, so I put a new primer bulb on and still had the same problem. Next I got a rebuild kit for the Zama carburetor and cleaned it, installed the kit, reassembled everything and put in new fuel lines and filter, but it still will not prime. There is no fuel in the bulb after pushing it numerous times and the bulb is easy to compress. Also this carburetor has only one adjustment screw, not two for high and low adjustment. This is new to me. Any help would be greatly appreciated.
   Thanks, Ken

Answer
hi ken

did you identify the carb and fit the correct repair kit ?  ie zama ciu, c1q  ie  rb16  , rb39

when you istalled   pump diaphram and gasket   and  metering diaphram and gasket  
which way did you fit the diaphrams and gaskets?

is the inlet screen clean ?

for the fuel pump side of carb always fit the pump diaphram on the carb then the gasket then the primer part then the cover with bulb

for the metering side of carb , fit needle ,return spring ,  hinge pin and lever and tighten screw down holding hinge pin , make sure lever tongue is set right ,( or machine may run rich or lean depending on how high or low it was set )then fit metering gasket  , then metering diaphram  then the metering cover and screws and tighten down

from memory these carbs are fixed hi speed and adjustable low speed only

check that the primer one way check valve is working ?

if carb is off machine will it start & run on 2 stroke prime no problem ?
if so this then rules out compression and spark and timming

be sure to check muffler for restriction ,  muffler is part of fuel system on 2 stroke engine
provided c/cases are  air and vaccuum tight    your problems will only be carby


cheers hope this helps  


ps let me know