High speed
Unsatisfactory performance at
high speed
Blocked fuel filter
Blocked fuel hose
Air in fuel pipes
Incorrect/unsatisfactory fuel
Vacuum pulse leakage
Blocked vacuum pulse pipe
Loose screws on the pump cover
Defective pump diaphragm
The needle valve is defective
The carburetor is not attached correctly
The lever arm of the needle valve is damaged
The lever arm of the needle valve does not operate correctly
The spring of the needle valve is damaged
The needle valve spring is not attached correctly
The control diaphragm is damaged
The control diaphragm has a defective seal
The needle valve is worn
Object in the needle valve guide
Increasing and decreasing speed
The engine does not increase
speed
Blocked fuel filter
Blocked fuel hose
Air in fuel pipes
Vacuum pulse leakage
Blocked vacuum pulse pipe
Loose screws on the pump cover
Defective pump diaphragm
The needle valve is defective
The carburetor is not attached correctly
The lever arm of the needle valve is damaged
The lever arm of the needle valve is too low
The lever arm of the needle valve does not operate correctly
The needle valve spring is not attached correctly
The control diaphragm is damaged
Blocked needle valve
The engine stops when decreas-
ing speed
Defective pump diaphragm
The lever arm of the needle valve is too high
The lever arm of the needle valve does not operate correctly
The needle valve is worn
Object in the needle valve guide
Can not increase speed
Defective heat insulation seal
66 - Troubleshooting
627 - 002 - 23.04.2018