Stihl MS 270 User Manual page 14

Condition
Engine speed drops quickly under
load – low power
Engine will not idle,
idle speed too high
14
Cause
Air filter dirty
Tank vent faulty
Leak in fuel line between tank
and fuel pump
Pump diaphragm damaged or
fatigued
Main jet bores or ports blocked
Fuel pickup body dirty
Fuel strainers dirty
Spark arresting screen dirty
Setting of high speed screw (H)
too rich
Throttle shutter not opened fully
Throttle shutter opened too wide
by idle speed screw (LA)
Engine leaking
Remedy
Clean the air filter
Replace tank vent
Seal connections or install a new
fuel line
Fit a new pump diaphragm
Clean the bores and ports
Clean the pickup body, fit a new
filter
Clean the fuel strainers
Clean or replace spark arresting
screen
Reset high speed screw (H)
correctly
Check linkage
Reset idle speed screw (LA)
correctly
Seal the engine
MS 270, MS 280