Regal LS4C Owner's Manual page 171

DIAGNOSTIC CHART
Problem
Power Loss
Excessive Vibration
ENGINE
Possible Cause
Damaged propeller/propeller hub slipping
Improper trim angle
Spark plugs fouled
Fuel system malfunction
Hull bottom fouled with debris
Excess water in bilge (leak)
Engine code system energized due to
malfunction (rpm's restricted).
Damaged propeller
Damaged propeller shaft
Loose/broken motor mount
Steering pivot loose or damaged
Debris caught on propeller
Ignition malfunction
Motor mount bolts loose
Failed gimbal bearing on drive input shaft
U-joint failure (more pronounced in tight turn.
171