Troubleshooting; Engine Does Not Start Or Is Hard To Start - Honda Nighthawk CB 750 1991 Service Manual

18. Troubleshooting
b g i n e ~ o e s
~ o t
Stan Or IS Hard TO Stan
I
:
Possible Cause
Engine Does Not Start Or Is Hard
Poor Performance At High Speed
18-3
To Start l8-' Poor Handling 18-4
Engine Lacks Power
8-2
Hydraulic Tappet
18-4
Poor Performance At Low And Idle
Speeds 18-3
1 . Check fuel flow to carburetor Not Reaching Carburetor
-.
Clogged fuel tube or fuel strainel
I
-
Sticking float valve
-
~ e a i h i n g Carburetor
I
clogged fuel tank breather
Disconnected or faulty auto fuel
valve vacuum tube
2. Perform a spark test Weak Or No Spark
.
Faulty spark plugs
t
I
.
Fouled spark plugs
Good Spark
Faulty ignition control module .
Broken or shorted spark plug wires
.
Broken or shorted ingition coil
.
Faulty ignition switch
.
Faulty ignition pulse generator
-
Faultv enaine stor, switch .
-
.
Loose or disconnected ignition
system wires
I
3. Test cylinder Compression
Low Compression
-.
Valve stuck open
-
Worn cylinder and piston rings
Compression Normal
Damaged cylinder head gasket
Seized valve
-
lmproper valve timing
i
4. Start by following normal procedure-Engine Starts But Stops
- 0
Improper choke operation
I
.
Carburetor incorrectly adjusted
~ n g i n e Does Not Fire
-
Intake pipe leaking
.
l m ~ r o ~ e r ianition timina (Faultv
. .
-
ignition control moduleor igniion
I
pulse generator)
Fuel contaminated
1
5.
Remove and inspect spark plug- Wet Plug
-.
Carburetor flooded
.
Choke closed
.
Throttle valve open
.
Air cleaner dirty