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Troubleshooting the 2 Stroke Outboard Motor

NOTE: When trouble-shooting power heads of 4-cycle outboard motors, follow procedures outlined for inboard engines.
START ALL MAJOR DIAGNOSIS WITH A COMPRESSION TEST.

DO NOT RUN MOTOR OUT OF WATER.

MOTOR REACTION

1  Manual starter rope pulls out, but pawls do not engage.
A  Friction spring bent or burred.
B  Excess grease on pawls or spring (too heavy of a grease used?)
C  Pawls bent or burred.

2  Starter rope does not return.
A  Recoil spring broken or binding (too heavy of a grease used?)
B  Starter housing bent.
C  Loose or missing parts.

3  Clattering manual starter.
A  Friction spring bent or burred.
B  Starter housing bent.
C  Excess grease on pawls or spring.
D  Dry starter spindle.
E  Just plum worn out...

4  Electric starter inoperative.
A  Loose or corroded connections or ground.
B  Starting circuit safety switch open, or out of adjustment.
C  Improper capacity or weak battery or corroded battery terminals
D  Faulty starter solenoid.
E  Moisture in electric starter motor.
F  Broken or worn brushes in starter motor.
G  Faulty fields.
H  Faulty armature.
I  Broken wire in harness or connector
J  Faulty starter key, push button or safety switch.
K  Worn or frayed insulation.

5  Electric starter does not engage but solenoid clicks.
A  Loose or corroded connections or ground.
B  Weak battery.
C  Faulty starter solenoid.
D  Broken wire in electric harness.
E  Loose or stripped post on starter motor.
F  See steps in number 4.
G  Bendix shaft rusted or bendix clutch broken

6  Hard to start or won't start.
A  Empty gas tank.
B  Gas tank air vent not open.
C  Fuel lines kinked or severely pinched.
D  Water or dirt in fuel system
E  Clogged fuel filter or screens.
F  Motor not being choked to start.
G  Engine not primed -- pump primer system.
H  Carburetor adjustments too lean (not allowing enough fuel to start engine).
I  Timing and synchronizing out of adjustment.
J  Manual choke linkage bent -- auto choke out of adjustment.
K  Spark plugs improperly gapped, dirty or broken.
L  Fuel tank primer inoperative (pressurized system).
M  Ignition points improperly gapped, burned or dirty or triggering (CD) system inoperative.
N  Loose, broken wire or frayed insulation in electrical system.
O  Reed valves not seating or stuck shut.
P  Weak coil or condenser.
Q  Faulty gaskets.
R  Cracked distributor cap or rotor or shorted rotor.
S  Loose fuel connector.
T  Amplifier (CD) inoperative.
U  Poor engine or ignition ground.
V  Faulty ignition or safety switch.
W  Low cranking speed.
X  Low voltage to ignition, when cranking.

7  Low speed miss or motor won't idle smoothly and slowly enough.
A  Improper fuel/oil mixture (very old gas?)
B  Timing and synchronizing out of adjustment (linkage fell off?)
C  Carburetor idle adjustment (mixture lean or rich).
D  Ignition points improper (gap, worn or fouled) or triggering (CD) system inoperative.
E  Weak coil or condenser (only way to know for sure... Replace it).
F  Loose or broken ignition wires.
G  Loose or worn magneto plate.
H  Spark plugs (improper gap or dirty incorrect plug / don't waste time try a new set)
I  Head gasket, reed plate gasket (blown or leaking).
J  Reed valve standing open or stuck shut.
K  Plugged crankcase bleeder, check valves, or lines.
L  Leaking crankcase halves.
M  Leaking crankcase seals (top or bottom).
N  Exhaust gases returning thru intake manifold (cowling seals missing or damaged).
O  Poor distributor ground (look for a grounding wire or add one).
P  Cracked or shorted distributor cap or rotor.
Q  Fuel pump diaphragm punctured (check spark plugs, usually one will be running very rich).
R  Accessory tachometer shorted or not compatible with ignition system.
S  Faulty ignition or safety switch.

8  High speed miss or intermittent spark.
A  Spark plugs improperly gapped or dirty.
B  Loose, leaking or broken ignition wires.
C  Breaker points (improper gap or dirty / worn cam or cam follower) or triggering (CD) system faulty.
D  Weak coil or condenser
E  Water in fuel.
F  Leaking head gasket or exhaust cover gasket.
G  Incorrect spark plug
H  Engine improperly timed.
I  Carbon or fouled combustion chambers.
J  Magneto, distributor, or CD triggering system poorly grounded.
K  Distributor oiler wick bad (points are hopping).
L  Accessory tachometer shorted or not compatible with ignition system.
M  Faulty ignition or safety switch.

9  Coughs, spits, slows.
A  Idle or high speed needles set too lean.
B  Carburetor not synchronized.
C  Leaking gaskets in induction system.
D  Obstructed fuel passages.
E  Float level set too low.
F  Improperly seated or broken reeds.
G  Fuel pump pressure line ruptured.
H  Fuel pump (punctured diaphragm), check valves stuck open or closed, fuel lines leak.
I  Poor fuel tank pressure (pressurized system).
J  Worn or leaking fuel connector.

10  Vibrates excessively or runs rough and smokes.
A  Idle or high speed needles set too rich.
B  Too much oil mixed with gas.
C  Carburetor not synchronized with ignition properly.
D  Choke not opening properly.
E  Float level too high.
F  Air passage to carburetor obstructed.
G  Bleeder valves or passages plugged.
H  Transom bracket clamps loose on transom.
I  Prop out of balance.
J  Broken motor mount.
K  Exhaust gases getting inside motor cover.
L  Poor ignition -- see steps in number 8.
M  Motor too low in water (excessive exhaust back-pressure).

11  Runs well, idles well for a short period, then slows down and stops.
A  Weeds or other debris on lower unit or propeller.
B  Insufficient cooling water (especially probable with inline).
C  Carburetor, fuel pump filter or screens dirty.
D  Bleeder valves or passages plugged.
E  Lower unit binding (lack of lubrication or bent).
F  Gas tank air vent not open.
G  Not enough oil in gas.
H  Combustion chambers and spark plugs fouled, causing pre-ignition.
I  Spark plug heat range too high or too low.
J  Wrong propeller (PreIgnition).
K  Slow speed adjustment too rich or too lean.

12  Won't start, kicks back, back fires into lower unit.
A  Spark plug wires reversed.
B  Flywheel key sheared.
C  Distributor belt timing off (magneto or battery ignition).
D  Timing and synchronizing out of adjustment.
E  Reed valves not seating or broken.
F  Poor engine or distributor ground.
G  Extremely lean operation

13  No acceleration, low top RPM
A  Improper carburetor adjustments.
B  Improper timing and synchronization.
C  Spark plugs (improper gap or dirty).
D  Ignition points (improper gap or faulty) / or triggering (CD) system.
E  Faulty coil or condenser.
F  Loose, leaking or broken ignition wires.
G  Reed Valves not properly seated or broken.
H  Blown head or exhaust cover gasket.
I  Weeds on lower unit or propeller.
J  Incorrect propeller.
K  Insufficient oil in gas.
L  Insufficient oil in lower unit.
M  Fuel restrictions.
N  Scored cylinder -- stuck rings.
O  Marine growth, hooks, rockers or change in load of boat, or flooded bottom.
P  Sticky magneto plate or distributor.
Q  Carbon build-up on piston head at deflector.
R  Marginal CD amplifier or pulse pack.

14  No acceleration, idles well but when put to full power dies down.
A  High or law speed needle set too lean.
B  Dirt or packing behind needles and seats.
C  High speed nozzle obstructed.
D  Float level too low.
E  Choke partly closed.
F  Improper timing and synchronization.
G  Fuel lines or passages obstructed.
H  Fuel filter obstructed. Fuel pump not supplying enough fuel.
I  Not enough oil in gas.
J  Breaker points improperly gapped or dirty.
K  Bent gearcase or exhaust tube.
L  Marginal CD amplifier or pulse pack.
M  Faulty spark plugs.
N  Incorrect propeller.
O  Roughness or damage on front of gearcase causing ventilation

15  Engine runs at high speed only by using hand primer.
A  Carburetor adjustments.
B  Dirt or packing behind needles and seat.
C  Fuel lines or passages obstructed.
D  Fuel line leaks.
E  Fuel pump not supplying enough fuel.
F  Float level too low.
G  Fuel filter obstructed.
H  Fuel tank or connector at fault.

16  Loss of power under heavy load.
A  Wrong propeller.
B  Weeds or other debris on lower unit or propeller.
C  Breaker points improperly gapped or dirty.
D  Stator plate loose
E  Ignition timing over advanced or late.
F  Faulty carburetion and/or faulty ignition.
G  Prop hub slips.
H  Scored cylinders or rings stuck.
I  Carbon build up on piston head at deflector.

17  Cranks over extremely easy on one or more cylinders.
A  Low compression.

  1. 1  Worn or broken rings.
    2  Scored cylinder or pistons.
    3  Blown head gasket.
    4  Loose spark plugs.
    5  Loose head bolts.
    6  Crankcase halves improperly sealed.
    7  Burned piston.

18  Engine won't crank over.
A  Manual start lock improperly adjusted.
B  Pistons rusted to cylinder wall.
C  Lower unit gears, prop shaft rusted or broken.
D  Broken connecting rod, crankshaft or driveshaft.
E  Coil heels binding on flywheel.
F  Engine improperly assembled.
G  Water in cylinders

19  Motor overheats.
A  Motor not deep enough in water.
B  Not enough oil in gas or improperly mixed.
C  Bad thermostat.
D  Seals or gaskets (burned, cracked or broken).
E  Impeller key not in place or broken.
F  Plugged water inlet, outlet or cavity.
G  Obstruction in water passages.
H  Broken, pinched or leaking water lines.
I  Improper ignition timing.
J  Motor not assembled properly.
K  Shorted heat light wiring.
L  Bad water pump impeller, plate, housing or seal.

20  Motor stops suddenly, freezes up.
A  No oil in gas, or no gas.
B  Insufficient cooling water.
C  No lubricant in gearcase.
D  Rusted cylinder or crankshaft.
E  Bent or broken rod, crankshaft, driveshaft, prop shaft, stuck piston.
F  Bad water pump or plugged water passages.

21  Motor knocks excessively.
A  Too much or not enough oil in gas.
B  Worn or loose bearings, pistons, rods or wrist pins.
C  Over advanced ignition timing.
D  Carbon in combustion chambers and exhaust ports.
E  Manual starter not centered.
F  Flywheel nut loose.
G  Flywheel hitting coil heels.
H  Bent shift rod (vibrating against exhaust tube).
I  Loose assemblies, bolts or screws.
J  Broken teeth in gearcase.

22  Generator or alternator will not charge.
A  Battery condition.
B  Connections loose or dirty.
C  Drive belt loose or broken.
D  Faulty regulator or cutout relay.
E  Field fuse or fusible wire in regulator blown.
F  Generator not polarized (D. C. generators).
G  Faulty generator or alternator.
H  Worn or sticking brushes and/or slip rings.
I  Faulty rectifier diodes (alternators)
J  Faulty ammeter.
K  CD voltage regulator faulty.
L  Rectifier not grounded.
M  CD safety circuit grounded.
N  Excessive electrical load on system

23  Low generator or alternator output and a low battery.
A  High resistance at battery terminals.
B  High resistance in charging circuit.
C  Faulty ammeter.
D  Low regulator setting.
E  Faulty rectifier diodes (alternators).
F  Faulty generator or alternator.
G  Excessive electrical load on system

24  Excessive battery charging.
A  Regulator set too high.
B  Regulator contacts stuck.
C  Regulator voltage winding open.
D  Regulator improperly grounded.
E  High resistance in field coil.
F  Regulator improperly mounted.
G  Insufficient battery size (unregulated systems).
H  No water in battery

25  Excessive fuel consumption.
A  Hole in fuel pump diaphragm.
B  Deteriorated carburetor gaskets.
C  Altered or wrong fixed jets.
D  Jets improperly adjusted.
E  Carburetor casting porous.
F  Float level too high.
G  Loose distributor pulley.
H  Incorrect propeller (high rpm).
I  Boat bottom fouled
J  Lower crankcase seal deteriorated

26  Shifter dog jumps
A  Worn shifter dog or worn gear dogs.
B  Worn or bent linkage.
C  Remote control adjustment.
D  Gearcase loose or sprung.
E  Exhaust housing bent.
F  Linkage out of adjustment.
G  Rear case cover or carrier loose

27  Electric shift inoperative or slips.
A  Improper remote control installation.
B  Faulty coils.
C  Faulty springs.
D  Faulty clutch and gear.
E  Faulty bearings.
F  Wrong lubricant.
G  Loose or sprung gearcase.
H  Shorted wiring or poor connections.

28  Undesirable Steering
A  Improperly set trim tab or corroded trim tab.
B  Improper trim angle setting
C  Bent steering ram.
D  Internal corrosion in steering cable or support tube.
E  Worn helm gearing.
F  Excessive number of bends or too tight bends in steering cable.
G  Loose mounting at helm or cable output end.
H Crushed or kinked cable.
I  Friction device at helm over tightened.
J  Leaks, dirt or low fluid level in hydraulic steerers.
K  Binding in swivel connections or motor swivel bracket.
L  Improper tension adjustment on dual cable systems.

 
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