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FJR Motorcycle Forums
Technical & Mechanical Problems
Where the FI gremlins come from
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<blockquote data-quote="jestal" data-source="post: 241957" data-attributes="member: 477"><p>That would be the pulse damper. I thought I remembered seeing one on the 06/07 in some of the earlier posts/pictures but wasn't sure. I would be very surprised to see a returnless system without one. It has a plastic bladder inside with air pressure in the bladder to absorb the pulsations....we call it a whoppee cushion.....</p><p></p><p>Hogwash.....???..... :huh: :huh: :huh: Indeed, the pressure "pulsations" or spikes are so brief in terms of time that no mechanical gauge in the world could track them. You need a very sensitive pressure transducer and a 'scope at the very least. Even if a gauge could track the pulses your eyes couldn't see the needle moving that fast. But, you are right, run the bike and the fuel pressure will stay perfectly constant...that is how a returnless system works as opposed to the fuel pressure changing constantly with load on the engine like the return systems did.</p><p></p><p>The presence of the pulse damper indicates that the problem with the water hammer was at least considered and corrective action taken. If the damper is working and is in the correct location it should take out much of the pressure pulsations from the water hammer effect of the injectors closing but there will still be some effect cylinder-to-cylinder that the ECM will take care of via electronic compensation of the pulse width.</p></blockquote><p></p>
[QUOTE="jestal, post: 241957, member: 477"] That would be the pulse damper. I thought I remembered seeing one on the 06/07 in some of the earlier posts/pictures but wasn't sure. I would be very surprised to see a returnless system without one. It has a plastic bladder inside with air pressure in the bladder to absorb the pulsations....we call it a whoppee cushion..... Hogwash.....???..... :huh: :huh: :huh: Indeed, the pressure "pulsations" or spikes are so brief in terms of time that no mechanical gauge in the world could track them. You need a very sensitive pressure transducer and a 'scope at the very least. Even if a gauge could track the pulses your eyes couldn't see the needle moving that fast. But, you are right, run the bike and the fuel pressure will stay perfectly constant...that is how a returnless system works as opposed to the fuel pressure changing constantly with load on the engine like the return systems did. The presence of the pulse damper indicates that the problem with the water hammer was at least considered and corrective action taken. If the damper is working and is in the correct location it should take out much of the pressure pulsations from the water hammer effect of the injectors closing but there will still be some effect cylinder-to-cylinder that the ECM will take care of via electronic compensation of the pulse width. [/QUOTE]
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FJR Motorcycle Forums
Technical & Mechanical Problems
Where the FI gremlins come from
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