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FJR Motorcycle Forums
Technical & Mechanical Problems
Considering a different take on abrubt throttle response due to Yamaha fuel cut off when coasting in gear
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<blockquote data-quote="SnowmobileGuy" data-source="post: 1075576" data-attributes="member: 20770"><p>Wfooshee,</p><p></p><p>In my post to ionbeam I screwed up and for some reason the edit button doesn’t show up.</p><p></p><p>The injectors are actually not digital. There is a transient component in their performance. There is basically an "attack", "sustain", and "decay" phase when they are fired, but true, you can't tell the injector to partially open. The hope is that the fuel volume and the pressure in the fuel rail provide enough capacitance for consistent operations, but metering fuel when a large portion of the "open" time is dwell time can be tricky. This issue can be further compounded by the inertia in the fuel system. A dead head system (i.e. no return line) can have most of the fuel in the rail sitting near motionless in low fuel demand situations. The fuel pump must be able to accelerate that fuel inertia in the rail and fuel line quickly when an injector is opened. You will see some dead head systems with a diaphragm at the end of the fuel rail. It’s there to provide capacitance. Enough of my verbiage as that has little to do with what I’m asking here.</p><p></p><p>Yes, I suspect you would need to use the speed signal as the EFI system doesn't shut the fuel off if you were to just let out the clutch while idling. Without as system flow chart, it’s hard to know. Chuck35 seems like he may know something about the system logic, but is having issue with his computer.</p></blockquote><p></p>
[QUOTE="SnowmobileGuy, post: 1075576, member: 20770"] Wfooshee, In my post to ionbeam I screwed up and for some reason the edit button doesn’t show up. The injectors are actually not digital. There is a transient component in their performance. There is basically an "attack", "sustain", and "decay" phase when they are fired, but true, you can't tell the injector to partially open. The hope is that the fuel volume and the pressure in the fuel rail provide enough capacitance for consistent operations, but metering fuel when a large portion of the "open" time is dwell time can be tricky. This issue can be further compounded by the inertia in the fuel system. A dead head system (i.e. no return line) can have most of the fuel in the rail sitting near motionless in low fuel demand situations. The fuel pump must be able to accelerate that fuel inertia in the rail and fuel line quickly when an injector is opened. You will see some dead head systems with a diaphragm at the end of the fuel rail. It’s there to provide capacitance. Enough of my verbiage as that has little to do with what I’m asking here. Yes, I suspect you would need to use the speed signal as the EFI system doesn't shut the fuel off if you were to just let out the clutch while idling. Without as system flow chart, it’s hard to know. Chuck35 seems like he may know something about the system logic, but is having issue with his computer. [/QUOTE]
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FJR Motorcycle Forums
Technical & Mechanical Problems
Considering a different take on abrubt throttle response due to Yamaha fuel cut off when coasting in gear
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