2004 Yamaha FZ6

I WAS RETURNING HOME TO PLANO, TX FROM A WEEKEND TRIP TO COLORADO. I WAS ABOUT AN HOUR AWAY FROM HOME, WHEN I STARTED TO EXPERIENCE ENGINE HESITATION WHENEVER I RELEASED AND REAPPLIED THE THROTTLE. THE NEXT DAY, THE HESITATION WAS GONE, BUT I NOTICED THAT MY FUEL MILEAGE HAD GONE WAY DOWN (FORMERLY 42-45 MPG TO THE CURRENT 35 MPG). THE ENGINE IS ALSO RUNNING RICH, ENOUGH THAT I CAN SMELL UNBURNT FUEL IN THE EXHAUST. THE ENGINE ALSO HAS STARTED TO IDLE ERRATICALLY, FLUCTUATING IN RPMS.

2004 YAMAHA FZ6 5K+ MILES. WHEN CRUISING AND KEEPING THE ACCELERATOR CONSTANT, ONE EXPERIENCES SUDDEN CHANGES IN ENGINE-TO-TRANSMISSION POWER FEED: THE BIKE SUDDENLY STARTS TO ACCELERATE OR SLOW DOWN. ONE MUST COMPENSATE CONSTATNLY FOR THAT ERRATIC ENGINE BEHAVIOR, WHICH TAKES AWAY FROM PAYING ATTENTION TO THE ROAD. IF DOWNSHIFTING, UPSHIFTING OR CLUTCH DISENGAGEMENT IS PERFORMED DURING THE ENGINE FALTERING, THE RESULT IS A STALLED OUT ENGINE UNLESS SHIFTING IS PERFORMED VERY QUICKLY. STALLING OUT WHILE DOWNSHIFTING FOR A FULL STOP AT AN INTERSECTION GETS DICEY GIVEN THE AMOUNT OF OIL/WATER USUALLY FOUND AT STOP LINES AND THEIR APPROACHES. THIS PROBLEM TENDS TO APPEAR AFTER ABOUT 20-30 MINUTES OF ENGINE OPERATION AT ALL SPEEDS, TEMPERATURES OF ENGINE OPRATION. IT CLUTCH IS DISENGAGED, THE ENGINE IDELS DOWN TO 400-500 RMP (INSTEAD OF THE USUSAL 11-12K) AND INVARIABLY STALLS. STARTING THE BIKE RIGHT BACK DOES NOT ALLEVIATE THE SITUATION. THE ONLY REMEDY I WAS ABLE TO FIND WAS TO TURN THE IGNITION OF, TURN IT BACK ON (EVEN AFTER 2 SECONDS) AND START EH BIKE AGAIN. IDLING RMPS COME BACK TO NORMAL AND THE BIKE RIDES FINE AFTER THAT. TURNED BIKE INTO DEALERSHIP, REPORTING THE ABOVE SYMPTOMS ALONG WITH REPORTS OF THROTTLE POSITION SENSOR PROBLEMS REPORTED BY OTHER FZ6 RIDERS. DEALER COULD NOT REPLICATE THE PROBLEM AND SIMPLY REPLACED IOL/GAS FILTERS, AS WELL AS OIL. UPON RECEIVING THE BIKE BACK FROM THE DEALERSHIP, OF COURSE THE PROBLEM CAME BACK.

2004 YAMAHA FZ6 13K+ MILES. DURING A SUSTAINED CRUISE, WITH A SUSTAINED RPM BETWEEN 4K AND 5K RPM, THE ENGINE BEGAN FALTERING/BOGGING DOWN AND RUNNING VERY ROUGH. ACCOMPANYING THIS ISSUE, THERE IS A MARKED SENSE OF DECELERATION UNLESS MORE THROTTLE IS APPLIED TO COMPENSATE FOR THE THE LOSS OF POWER; THE DECELERATION, AT TIMES, CAN BE QUITE SUDDEN. THIS PROBLEM TENDS TO OCCUR BEYOND 1/2 HOUR OF OPERATION. IF DOWNSHIFTING OR UPSHIFTING IS PERFORMED DURING THE ENGINE FALTERING, THE RESULT IS A STALLED OUT ENGINE UNLESS SHIFTING IS PERFORMED VERY QUICKLY. STALLING OUT WHILE DOWNSHIFTING FOR A FULL STOP AT AN INTERSECTION GETS DICEY GIVEN THE AMOUNT OF OIL/WATER USUALLY FOUND AT STOP LINES AND THEIR APPROACHES. TURNED BIKE INTO DEALERSHIP, REPORTING THE ABOVE SYMPTOMS ALONG WITH REPORTS OF THROTTLE POSITION SENSOR PROBLEMS REPORTED BY OTHER FZ6 RIDERS. DEALER COULD NOT REPLICATE THE PROBLEM AND SIMPLY REPLACED THE SPARK PLUGS. UPON RECEIVING THE BIKE BACK FROM THE DEALERSHIP, THE PROBLEM PROMPTLY RETURNED ABOUT 40 MINUTES INTO THE FIRST RIDE.

AT ABOUT 6200 MILES WHILE PULLING UP TO A LIGHT OF A STEADY RUN MY MOTORCYCLE WOULD DIE. RESTART IT, AND IT WOULD BE MISFIRE REAL BADLY AND DIE AGAIN. TAKE KEY OUT AND BACK IN IT WOULD FIRE UP JUST FINE, FOR THE TIME BEING. FIRST TIME THIS HAPPENED I WAS ABOUT TO TAKE A TURN, HAD THE CLUTCH IN DOWN SHIFT, THEN BRAKED FOR AN ONCOMING CAR, AS I STARTED TO LEAN I WAS LETTING THE CLUTCH OUT, WHEN LOW AND BEHOLD THE ENGINE DIED. SO IT JUST LOCKED UP. LUCKILY, I WAS ABLE TO GET THAT CLUTCH IN BEFORE IT WENT OVER. TOOK IT TO THE DEALER AND THEY HAD IT A COUPLE DAYS AND SAID THERE WERE NO CODES, AND THEY COULD NOT DUPLICATE THE COMPLAINT. IT ACTED UP WHEN EVER IT FELT LIKE. SOMETIMES IT RAN FINE FOR WEEKS, THEN SOMETIMES IT MESSES UP A BUNCH IN 1 WEEK. I'VE RESEARCHED THIS TOPIC ONLINE, AND FOUND MANY OTHERS WITH SAME PROBLEM. *AK

1. BIKE WAS BADLY HESITATING STARTING OFF IN 1ST GEAR FROM A STOP. 2. TURNING THE THROTTLE TO ACCELERATE WOULD SOMETIMES PITCH ME FORWARD ON THE START AS THE ENGINE HESITATED, THEN TURNING IT A BIT MORE WOULD ALMOST THROW ME OFF AS IT ACCELERATED. 3. ONE DEALERSHIP TRIED ADJUSTING THE THROTTLE POSITION SENSOR (TPS) AND IT ACTUALLY MADE THE PROBLEM WORSE. THE NEXT DEALERSHIP REPLACED THE TPS UNIT AND IT HAS BEEN RUNNING FINE SINCE. *AK

MY MOTORCYCLE WILL STALL AND/OR RUN ROUGH OCCASIONALLY, AND NOT IDLE WITHOUT ADDITIONAL THROTTLE INPUT. IF I TURN THE IGNITION OFF AND RESTART THE MOTORCYCLE IT WILL FIX THE PROBLEM FOR A PERIOD OF TIME. I AM VERY CONCERNED THAT THE MOTORCYCLE WILL ENCOUNTER THIS PROBLEM WHILE TURNING AND CAUSING INSTABILITY THAT MIGHT CONTRIBUTE TO A CRASH. IN ADDITION, I DO NOT LIKE HAVING THE THOUGHT OF THIS PROBLEM IN MY MIND EVERYTIME I AM RIDING, AS IT TAKES ENOUGH CONCENTRATION TO AVOID OTHER VEHICLES AND MONITOR ROAD CONDITIONS. I HAVE NOT REPAIRED THE PROBLEM YET. THANK YOU FOR YOUR TIME.*AK