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FJR Motorcycle Forums
Technical & Mechanical Problems
Intermittent fault, loss of power, acceleration error, gen 1
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<blockquote data-quote="torch" data-source="post: 1459850" data-attributes="member: 1295"><p>It certainly sounds like it is not adding fuel when you open the throttle. If it happens again, I would immediately (after pulling over) put it in Diag mode and check the TPS values as you twist the throttle to verify smooth and consistent readings. While there, I would also verify that the intake air pressure and ambient air pressure sensors values make sense -- with the engine off, they should be darn near equal and at the current ambient pressure. The ECU looks at the difference to calculate the volume of air entering the engine.</p><p></p><p>So long as a sensor is within the defined acceptable range, the ECU will trust the values it provides and calculate the mixture accordingly. They have to be completely bonkers before the ECU throws a code, lights the light and drops into fail-safe mode.</p><p></p><p>While a plugged tank vent is certainly a possibility, I don't think your description fits the classic symptoms. A plugged vent issue is usually consistent and doesn't go away. </p><p></p><p>An overheated fuel pump is certainly possible -- the Gen 1 airflow famously heats the fuel tank, especially as fuel level drops. Google can produce any number of attempts to alleviate the issue. Perhaps two with the best feedback are "Chromeit's heat fix" combined with adding a gen 2 style heat shield under the tank using aluminized heat insulation from the local hardware store. </p><p></p><p>Another possibility is a sticking fuel pressure relief valve not responding to the drop in pressure as the throttle is opened. Which again could be caused by heat. </p><p></p><p>Good luck! Intermittent issues are particularly difficult too trace.</p></blockquote><p></p>
[QUOTE="torch, post: 1459850, member: 1295"] It certainly sounds like it is not adding fuel when you open the throttle. If it happens again, I would immediately (after pulling over) put it in Diag mode and check the TPS values as you twist the throttle to verify smooth and consistent readings. While there, I would also verify that the intake air pressure and ambient air pressure sensors values make sense -- with the engine off, they should be darn near equal and at the current ambient pressure. The ECU looks at the difference to calculate the volume of air entering the engine. So long as a sensor is within the defined acceptable range, the ECU will trust the values it provides and calculate the mixture accordingly. They have to be completely bonkers before the ECU throws a code, lights the light and drops into fail-safe mode. While a plugged tank vent is certainly a possibility, I don't think your description fits the classic symptoms. A plugged vent issue is usually consistent and doesn't go away. An overheated fuel pump is certainly possible -- the Gen 1 airflow famously heats the fuel tank, especially as fuel level drops. Google can produce any number of attempts to alleviate the issue. Perhaps two with the best feedback are "Chromeit's heat fix" combined with adding a gen 2 style heat shield under the tank using aluminized heat insulation from the local hardware store. Another possibility is a sticking fuel pressure relief valve not responding to the drop in pressure as the throttle is opened. Which again could be caused by heat. Good luck! Intermittent issues are particularly difficult too trace. [/QUOTE]
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FJR Motorcycle Forums
Technical & Mechanical Problems
Intermittent fault, loss of power, acceleration error, gen 1
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