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Case Study Fault classification Reproducibility of phenomenon Example fault Difficulty ・ Engine doesn't start Phenomenon ・ Starter doesn't turn always present ・ Clutch slipping Low ・ Vibration in handlebars, etc Fault Phenomenon in some conditions ・ Bad starting in cold weather ・ Strange engine noise after warming up Low-medium ・ Stalling while moving, etc Phenomenon does not occur (cannot be confirmed) ・ Stalling while motorcycle moving ・ Hesitation while moving High ・ Irregular flat battery, etc ・ Bad fuel efficiency Not a fault ・ High oil usage, etc *These are examples of when customers are often mistaken, and some may be actual faults High STEP.1 Customer Consultation • • Yesterday, I tried to start the engine, but the starter motor did not turn I thought the battery was flat, so I bought a new one from a store nearby, and replaced it myself • The starter motor then started to work, but the engine wouldn't start This customer purchased the motorcycle years ago from your dealership From the customer management ledger, we were able to confirm the following information Step Phenomenon reproduction Given that the engine doesn't start, we can quickly confirm the phenomenon with the customer As detailed by the customer, the starter motor works properly, but the engine does not catch, and the engine won't start We have been able to confirm this phenomenon with the customer Step Phenomenon identification The customer complaint and the phenomenon are clearly the same "The starter motor works, but the engine does not start" The phenomenon that "The engine does not catch, and the engine won't start" can be identified. Step Malfunction Y/N judgment ・ Malfunction Definition ・ A malfunction means that there is an abnormality in part of the motorcycle, meaning it does not operate smoothly With the motorcycle in normal operating condition, if the symptom of "The starter motor turns, but the engine does not start" occurs, then what could this indicate? ・ No gasoline ・ Gasoline has deteriorated ・ An accessory (immobilizer, etc.) is operating ・ Unique usage conditions, etc • After confirming these facts, if the motorcycle is in fact normal, then the phenomenon of "The starter motor works, but the engine does not start" would not occur From this, we can make a judgment that there is indeed a malfunction with the motorcycle Step Listing possible causes Characteristics cause diagram Characteristics cause diagram Step Cause targeting Narrowing down the cause from simple inspection Simple inspection details Parts covered When the main switch is turned ON, does the engine warning light come on for 1.4 sec., then go out? ECU, sensors, actuators, Engage the starter motor for a few seconds Does the engine warning light flash? Harness/connector ② When the main switch is turned ON, can the fuel pump be heard? Fuel pump ③ When engaging the starter motor, does the engine turn smoothly and with no abnormal noises? Engine (internal parts) ④ When turning the engine over, is there exhaust pressure from the muffler? Muffler ⑤ When turning the engine over with the fuel tank cap removed, does the engine start? Tank cap air vent ⑥ Are there any oil or gasoline leaks? Inspect for oil or lubricant leakage ① Narrowing down the cause from simple inspection ① Checking parts ECU, sensors, actuators, Harness/connector Inspection details When the main switch is turned ON, does the engine warning light come on for 1.4 sec., then go out? Engage the starter motor for a few seconds Does the engine warning light flash? Reason this The ECU has self-diagnosis functionality, and whenever an abnormality is detected in signals input into sensors and can be excluded actuators, the engine warning light will flash, notifying the rider of an abnormality Narrowing down the cause from simple inspection ② Checking parts Fuel pump Inspection details When the main switch is turned ON, can the fuel pump be heard? Reason this The fuel pump operates for approximately seconds after the main switch is turned ON, ensuring fuel pressure to the can be excluded injectors From the sound of the fuel pump operating, you can determine that there is no problem with the fuel pump Checking parts Engine (internal parts) Inspection details When engaging the starter motor, does the engine turn smoothly and with no abnormal noises? Reason this Because the engine is turning smoothly, without any abnormal sounds, you can determine that there is no serious can be excluded damage to the internal parts Checking parts Muffler Inspection details When turning the engine over, is there exhaust pressure from the muffler? Reason this When turning the engine over, if there is exhaust pressure from the muffler, then you can determine that there is no can be excluded blockage in the muffler ③ ④ Narrowing down the cause from simple inspection Checking parts Fuel Tank cap air vent Inspection details When turning the engine over with the fuel tank cap removed, does the engine start? Reason this When turning the engine over with the fuel tank cap removed, if the engine starts, then this indicates that the air vent is can be excluded blocked If the engine doesn't start, then this can be excluded Inspection details Are there any oil or gasoline leaks? Reason this Visually inspect the tank cap, hoses, and the exterior of the engine If no oil or gasoline leaks are detected, then these can be excluded can be excluded ⑤ ⑥ Narrow down from simple inspection results Narrow down from information of diagnostic questions ・ Organizing information ・ Customer Voice ・ Yesterday, I tried to start the motor, but the starter motor did not turn ・ I thought the battery was flat, so I bought a new one from a store nearby, and replaced it myself ・ The starter motor then started to work, but the engine wouldn't start Who? □Engine doesn't start for any user □Customer : 40 years old male, 20 years experience riding motorcycles When (or from when)? □Customer noticed yesterday that the engine didn't start ・ I'd been hurt, so I didn't ride the motorcycle for months Where ・ months ago, there was no problem with it □The engine doesn't start in any location At what times? □Engine doesn't start at any time What & where? □Engine doesn't start How? □The engine does not catch, and the engine won't start □The starter motor is working properly Other information □The engine warning light does not flash □There is gas in the tank The gasoline has not deteriorated □When the main switch is turned ON, the fuel pump can be heard □When turning the engine over, there is exhaust pressure from the muffler □There are no oil or gasoline leaks □The customer changed the battery Narrow down from information of diagnostic questions Information ・ months ago, there was no problem with it Reason this can be Given that months ago, there was no problem with the motorcycle, excluded we can exclude causes relating to wear, insufficient adjustment or others However, electrical problems appear suddenly, therefore these cannot be eliminated The Result of cause targeting Step Inspection Of those remaining expected causes, perform inspections on those items which can be inspected efficiently and easily Check Fuel Supplying & Injection Condition by Spark Plug Check Injector Operation by YDT (Diagnostic function) Step Cause identification The cause of the malfunction may be "injector plunger sticking", but what is the root cause of this? What is the root cause? “Customer didn't ride the motorcycle for months" "deteriorated gasoline and the engine not running for a long time" Step Part replacement & adjustment When the injector is identified as the cause of the malfunction, replace the parts However, simply replacing the injectors will not remove the root cause of the malfunction While the cause of the engine not starting was the injector plunger sticking, the root cause was deteriorated gasoline Therefore, even if there were no problems with visual or smell checks of the gasoline, it is a good idea to replace the old gasoline in the tank Step Cause identification The cause of the malfunction may be "injector plunger sticking", but what is the root cause of this? What is the root cause? “Customer didn't ride the motorcycle for months" "deteriorated gasoline and the engine not running for a long time" Step Part replacement & adjustment When the injector is identified as the cause of the malfunction, replace the parts However, simply replacing the injectors will not remove the root cause of the malfunction While the cause of the engine not starting was the injector plunger sticking, the root cause was deteriorated gasoline Therefore, even if there were no problems with visual or smell checks of the gasoline, it is a good idea to replace the old gasoline in the tank Step 10 Final inspection Step 11 Explanation to customer When the injectors and gasoline have been replaced, check that the engine starts After checking, explain to the customer the cause of the malfunction "Because the motorcycle was not used for a long period of time, the gasoline deteriorated The injector plungers stuck, meaning that fuel could not be injected This is why the engine wouldn't start" When explaining this, you should give advice on storing the motorcycle For example, "when not using the motorcycle for a long time, you should disconnect the negative lead from the battery terminal", and "periodically start the engine" Summary In this case study, carrying out troubleshooting using the correct procedure lets us identify the cause of the malfunction through an inspection of the spark plugs For example, even if the cause of the malfunction was not injector plunger sticking, we can list possible causes as well as logically narrow these causes down, letting us rapidly return to troubleshooting Additionally, obtaining the important information "I didn't ride the motorcycle for months" lets us identify the root cause, as well as provide the customer with advice on preventing its recurrence As seen here, carrying out troubleshooting in the correct order is fundamental to rapidly and accurately rectifying the problem Please ensure you understand the importance of this, as well as the various points in each of the procedures Diagnostic questions: obtain information by using the basic items in the diagnostic questions, organize the information, and focus in upon the important information Listing possible causes: with a wide perspective, create a characteristics cause diagram that identifies as many expected causes as possible Cause targeting: use simple inspections and information gained from diagnostic questions to logically identify the cause Inspection: consider the most effective inspection methods and procedures Cause identification: identify the root cause of the malfunction Additional Study In recent years, the increasing usage of fuel injection means we haven’t seen significant amounts of problems caused by deterioration of gasoline In order to prevent the deterioration of gasoline, we should try as much as possible to prevent its contact with the outside air, but in this regard, the structure of fuel injection is superior to that of carburetors However, even fuel injection is not totally sealed off, and problems with long-term storage are usually attributable to the fuel injectors ● Injector operation ● Plunger sticking Gasoline deteriorates when left for a long time, and gum may form, which can cause sticking on sliding surfaces and on the tip of plungers Fuel can therefore no longer be injected, and the engine won't start [Inspection method] In function diagnostics mode, operate the injectors and listen to the sound If the sound of the injectors cannot be heard, then they may be stuck [How to remedy] Use an injector cleaner to clean the injectors If no improvement is seen, repeat several times ● Nozzle blockage Gum formed from deterioration of gasoline blocks the injector nozzle Depending on the degree of blockage, different symptoms may present including failure to start, low power, bad starting, hesitation, etc [Inspection method] ・ Visually check the injection (nozzle) status ・ Use the injector tester to check the injector angle and injection quantity [How to remedy] Use an injector cleaner to clean the injectors If no improvement is seen, repeat several times The above are typical problems that occur with the deterioration of gasoline, but most of these occur after long storage Gasoline deterioration is significantly influenced by the quality of the gasoline and by the temperature change in the storage location, but this can be prevented by starting the engine at least once a month ... engine doesn't start in any location At what times? □Engine doesn't start at any time What & where? □Engine doesn't start How? □The engine does not catch, and the engine won't start □The starter motor... tried to start the motor, but the starter motor did not turn ・ I thought the battery was flat, so I bought a new one from a store nearby, and replaced it myself ・ The starter motor then started... tried to start the engine, but the starter motor did not turn I thought the battery was flat, so I bought a new one from a store nearby, and replaced it myself • The starter motor then started