Yamaha C40 Manual

 
Maintenance 
56 
the screw before installing it.
4. Remove the oil level plug to allow the oil
to drain completely.
CAUTION:
 
ECM00710  
Inspect the used oil after it has been
drained. If the oil is milky, water is getting
into the gear case which can cause gear
damage. Consult a Yamaha dealer for re- 
pair of the lower unit seals.
NOTE:
 
For disposal of used oil consult your Yamaha 
dealer.
5. With the outboard motor in a vertical po-
sition, and using a flexible or pressur-
ized filling device,...

 
Maintenance 
57 
suction pipe) in a suitable cleaning sol-
vent. Allow the filter to dry.
5. Replace the gasket with a new one. Re-
install the fuel joint assembly and tighten
the screws firmly. 
EMU29312 
Inspecting and replacing anode(s) 
Yamaha outboard motors are protected from
corrosion by sacrificial anodes. Inspect the
external anodes periodically. Remove scales
from the surfaces of the anodes. Consult a
Yamaha dealer for replacement of external
anodes.
CAUTION:
 
ECM00720  
Do not paint anodes,...

 
Maintenance 
58 
followed by milk of magnesia, beaten
egg, or vegetable oil. Get immediate
medical attention.
Batteries also generate explosive hydro-
gen gas; therefore, you should always
follow these preventive measures: 
 
Charge batteries in a well-ventilated ar-
ea. 
 
Keep batteries away from fire, sparks,
or open flames (for example: welding
equipment, lighted cigarettes, and so
on.) 
 
DO NOT SMOKE when charging or han-
dling batteries.
KEEP BATTERIES AND ELECTROLYTIC 
FLUID OUT OF REACH OF...

 
Maintenance 
59 
minal. 
EMU29370 
Disconnecting the battery 
Disconnect the BLACK cable from the NEG-
ATIVE (-) terminal first. Then disconnect the
RED cable from the POSITIVE (+) terminal. 
EMU29390 
Checking top cowling 
Check the fitting of the top cowling by push-
ing it with both hands. If it is loose have it re-
paired by your Yamaha dealer. 
EMU29400 
Coating the boat bottom 
A clean hull improves boat performance. The
boat bottom should be kept as clean of ma-
rine growth as possible. If...

 
60 
Trouble Recovery 
EMU29424 
Troubleshooting 
A problem in the fuel, compression, or igni-
tion systems can cause poor starting, loss of
power, or other problems. This section de-
scribes basic checks and possible remedies,
and covers all Yamaha outboard motors.
Therefore some items may not apply to your
model.
If your outboard motor requires repair, bring
it to your Yamaha dealer.
If the engine trouble warning indicator is
flashing, consult your Yamaha dealer. 
Starter will not operate. 
Q. Is...

 
Trouble Recovery 
61 
Q. Is fuel system obstructed?
A. Check for pinched or kinked fuel line or
other obstructions in fuel system.
Q. Is fuel contaminated or stale?
A. Fill tank with clean, fresh fuel.
Q. Is fuel filter clogged?
A. Clean or replace filter.
Q. Have ignition parts failed?
A. Have serviced by a Yamaha dealer.
Q. Has warning system activated?
A. Find and correct cause of warning.
Q. Is spark plug gap incorrect?
A. Inspect and adjust as specified.
Q. Is ignition wiring damaged or poorly...

 
Trouble Recovery 
62 
A. Have serviced by a Yamaha dealer.
Q. Is load on boat improperly distributed?
A. Distribute load to place boat on an even
plane.
Q. Is water pump or thermostat faulty?
A. Have serviced by a Yamaha dealer.
Q. Is there excess water in fuel filter cup?
A. Drain filter cup. 
Engine power loss. 
Q. Is propeller damaged?
A. Have propeller repaired or replaced.
Q. Is propeller pitch or diameter incorrect?
A. Install correct propeller to operate out-
board at its recommended speed...

 
Trouble Recovery 
63 
Q. Is fuel joint connection incorrect?
A. Connect correctly.
Q. Is heat range of spark plug incorrect?
A. Inspect spark plug and replace it with rec-
ommended type.
Q. Is high pressure fuel pump drive belt bro-
ken?
A. Have serviced by a Yamaha dealer.
Q. Is engine not responding properly to shift
lever position?
A. Have serviced by a Yamaha dealer. 
Engine vibrates excessively. 
Q. Is propeller damaged?
A. Have propeller repaired or replaced.
Q. Is propeller shaft damaged?
A....

 
Trouble Recovery 
64
NOTE:
 
Consult your Yamaha dealer if the new fuse 
immediately blows again. 
EMU29522 
Power trim and tilt / power tilt will not 
operate 
If the engine cannot be tilted up or down with
the power trim and tilt / the power tilt because
of a discharged battery or a failure with the
power trim and tilt unit / the power tilt unit, the
engine can be tilted manually.
1. Loosen the manual valve screw by turn-
ing it counterclockwise until it stops.
2. Put the engine in the desired...

 
Trouble Recovery 
65 
wheel or other moving parts when the
engine is running. Do not install the
starter mechanism or top cowling after
the engine is running. 
 
Do not touch the ignition coil, spark
plug wire, spark plug cap, or other elec-
trical components when starting or op-
erating the motor. You could get an 
electrical shock. 
EMU29573 
Emergency starting engine 
1. Remove the top cowling.
2. Disconnect the start-in-gear protection
cable from the starter, if equipped.
3. Remove the...