Honda BF40D Owner's Manual page 104

TAKING CARE OF UNEXPECTED PROBLEMS
ENGINE WILL NOT START
Possible Cause
Battery connections loose or corroded.
Battery discharged.
Fuse(s) blown.
Spark plugs faulty, fouled, or improperly gapped.
Spark plugs wet with fuel (flooded engine).
Fuel system malfunction, fuel pump failure, ignition
malfunction, stuck valves, starter malfunction, switch
malfunction, or electrical problem in the starting circuit,
etc.
102
Correction
Clean and tighten battery connections.
Recharge battery.
Replace fuse(s) (p. 105).
Gap or replace spark plugs (p. 78).
Dry and reinstall spark plugs. Start engine with the
throttle open.
Use starting procedure (p. 45, 48); if engine still will not
start, then take outboard motor to an authorized Honda
Marine dealer, or refer to the shop manual.