Mercury 40 SeaPro Operation, Maintenance & Installation Manual page 72

CARBURETOR ADJUSTMENTS
Slow Speed Mixture Adjustment
1. Before starting engine, turn the slow speed mixture screw in until it is
lightly seated then back it out 1‑1/4 turns.
2. With boat tied securely to dock, start engine and allow it to warm up.
3. Shift the outboard into forward gear while maintaining idle speed.
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4. Turn the slow speed mixture screw slowly in until the engine starts to
misfire or stall due to a lean mixture. Note the position of the screw slot.
5. Turn the slow speed mixture screw slowly out until the engine starts to
load up or fire unevenly due to a rich mixture. Note the position of the
screw slot.
6. Set the slow speed mixture screw midway between the rich and lean
setting. When in doubt, set the mixture slightly rich rather than too lean.
MAINTENANCE
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