Try to find out exactly what problem occurred under exactly what conditions by asking the rider; knowing this information may help you reproduce the problem.
The following sample diagnosis sheet will help prevent you from overlooking any areas, and will help you decide if it is a DFI system problem, or a general engine problem.
Sample Diagnosis Sheet
Rider name: | Registration No. (license plate No.): |
Year of initial registration: | Model: |
Engine No.: | Frame No.: |
Date problem occurred: | Mileage: |
Environment when problem occurred | |
Weather | □fine, □cloudy □rain, □snow, □always, □other |
Temperature | □hot, □warm, □cold, □very cold, □always |
Problem frequency | □chronic, □often, □once |
Road | □street, □highway, □mountain road (□uphill, □downhill), □bumpy, □pebble |
Altitude | □normal, □high (about 1 000 m or more) |
Motorcycle conditions when problem occurred | |
FI indicator light (LED) | □light up immediately after ignition switch ON, and goes off after 1-2 seconds (normal) |
□lights blinks immediately after ignition switch ON, and stays on (DFI problem) | |
□lights up immediately after ignition switch ON, but goes off after about 10 seconds (DFI problem) | |
□unlights (light (LED), ECU or its wiring fault) | |
□sometimes lights up (probably wiring fault) | |
Starting difficulty | □starter motor not rotating |
□starter motor rotating but engine doesn't turn over | |
□starter motor and engine don't turn over | |
□no fuel flow (□no fuel in tank, □no fuel pump sound) | |
□engine flooded (do not crank engine with throttle opened, which promotes engine flooding) | |
□no spark | |
□other | |
Engine stops | □right after starting |
□when opening throttle grip | |
□when closing throttle grip | |
□when moving off | |
□when stopping the motorcycle | |
□when cruising | |
□other | |
Poor running at low speed | □very low idle speed, □very high idle speed, □rough idle speed |
□battery voltage is low (charge the battery) | |
□spark plug loose (tighten it) | |
□spark plug dirty, broken, or gap maladjusted (remedy it) | |
□backfiring | |
□afterfiring | |
□hesitation when acceleration | |
□engine oil viscosity too high | |
□brake dragging | |
□engine overheating | |
□clutch slipping | |
□other | |
Poor running or no power at high speed | |
□spark plug loose (tighten it) | |
□spark plug dirty, broken, or gap maladjusted (remedy it) | |
□spark plug incorrect (replace it) | |
□knocking (fuel poor quality or incorrect, → use high-octane gasoline) | |
□brake dragging | |
□clutch slipping | |
□engine overheating | |
□engine oil level too high | |
□engine oil viscosity too high | |
□other |
Note: This is not an exhaustive list, giving every possible cause for each problem listed. It is meant simply as a rough guide to assist the troubleshooting for some of the more common difficulties. The ECU may be involved in the DFI electrical and ignition system troubles. If these parts and circuits are checked out good, be sure to check the ECU for ground and power supply. If the ground and power supply are checked good, replace the ECU.