Husqvarna 531RB Workshop Manual page 58

Idle speed (low speed)
The engine stops at idle speed
High speed
Unsatisfactory performance at
high speed
Increase and decrease speed
The engine does not increase
speed
58 - Troubleshooting
The stop screw for the throttle does not operate correctly
Blocked fuel filter
Blocked fuel hose
Air in fuel pipes
The needle valve is defective
Defective heat insulation seal
The lever arm of the needle valve is too high
The lever arm of the needle valve does not operate correctly
The needle spring valve is damaged
The needle valve spring is not attached correctly
The needle valve is worn
Object in the needle valve groove
Blocked fuel filter
Blocked fuel hose
Air in fuel pipes
Incorrect/unsatisfactory fuel
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 needle valve spring is damaged
The needle valve spring is not attached correctly
The needle valve is worn
Object in the needle valve groove
Blocked fuel filter
Blocked fuel hose
Air in fuel pipes
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
Blocked needle valve
935 - 001 -