My 2002 Has A Intermittant Running Problem. It Will Hesitate And When I Mean Hesitate It Is Like It Has Shut Off . This Usually Happens In Part Throttle Below 5000 Revs . It Will Not Have Any Throttle Response Like It Has Shut Off Then If I Open The Throttl Quite A Bit Further It Will Start To Respond. It Even Has Shut Off Completly Two Or Three Times When Slowing Down Or Coming To A Stop. Also It Sometimes Feels Like That It Is Running Rough In The Mid Range Around 4000 To 5000 Revs. Any Help Would Be Appreciated
Since your VFR is FI (fuel injected), I can rule out a carb problem. It can however be a few other related things. I am thinking along the lines of fuel starvation. Have you replaced the fuel filter? Could also be the fuel pump itself. There may be other more simple things or more complicated things. I am trying to start small and work from there. The other thing that comes to mind is the ECU, which has the fuel map for the FI. But I don't know the failure rate on that but I suspect it's very low as I have never had an ECU, at least in a car, fail. I would start with checking the plugs and wires, and the fuel filter, if you have not already changed it. If those are good, I would move on to the pump itself and make sure it is pumping as it should. Oh, one other thing just popped in my head....it might be the FPR, fuel pressure regulator. A friend and a F4i that the FPR went bad and his bike ran poorly and I am thinking it had similar symptoms as yours. Good luck :thumb:
Had a similar issue. Ran a diagnostic, most manuals explain how, and got a MIL code indication of a vacuum hose being loose on the airbox. Checked and moved on but the problem persisted. You may have already done this. Also did what Vinny suggested with the fuel pump, filter, plugs and wires, no change but makes sense to check these also. Moved on from there and began checking cylinder pick-up connections. Re-connecting and cleaning of these did the trick, in my case I believe it was the front left cylinder (a bit more dirty than the others). Suspect connection was likely sending lousy info to the ECU which was trying to compensate. No more issues, that was 13k ago. If that doesn't work, I'd be headed to the throttle position sensor... Hope this helps.
