11Series 4180 Powerhead
Condition Cause Remedy
Engine will not idle,
idle speed too high
Throttle shutter opened too wide by
idle speed screw
Reset idle speed screw
Intake stub leaking Seal or replace intake stub
Engine stops while idling Idle jet bores or
ports blocked
Clean jet bores and ports and blow
clear with compressed air
Idle jet too rich Screw down low speed screw (L)
slightly
Setting of idle speed screw
incorrect – throttle shutter
completely closed
Set idle speed screw (LA) correctly
Engine speed drops quickly under
load – low power
Air filter dirty Clean the air filter
Tank vent faulty Clean the tank vent, replace if
necessary
Leak in fuel hose between tank to
fuel pump
Seal connections or install new fuel
hose
Pump diaphragm damaged or
fatigued
Fit new pump diaphragm
Main jet bores or ports blocked Clean bores and ports
Fuel pickup body dirty Fit new pickup body
Fuel strainers dirty Clean fuel strainers
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