mcride Posted April 5, 2016 Share Posted April 5, 2016 I have developed the following problem that I hope someone may have some suggestions to help me. My engine won't take wide open throttle past about 7500 rpm. At that rpm the engine just suddenly slows, then leaps ahead, then abruptly slows again, then leaps ahead, etc. It feels like fuel starvation but it could be electrical. It is very abrupt with only some slight stumbling just before it starts the serious failure. It will run to redline if not too much throttle is given. The problem started suddenly and now does it every time I try to run toward the redline in all gears. The bike has 26,000 miles and for the last 4,000 miles it has an Akropovic ti pipe and ECU flash by 2WDW for the pipe. I have had no engine running issues prior to this. I did a service about 900 miles ago including plugs, air filter, valve check, and throttle body sync. I have checked for a kinked fuel line and any blockage of the airbox. There was no code shown on the dash and the check engine light has not come on. I've put it in diagnostic mode and there are no fault codes. There doesn't seem to be a fuel filter to replace other than one that is on the fuel pump so I can't just try a fuel filter without buying a new fuel pump. I have spoken briefly with 2WDW and they were helpful but we were not able to come up with a solution. I have done more diagnostic work since I spoke with them and I hope to speak with them again to see if they can point me in the right direction. For now, I don't know what to investigate. Thanks for any help. Link to comment Share on other sites More sharing options...
Premium Member clint Posted April 5, 2016 Premium Member Share Posted April 5, 2016 I have developed the following problem that I hope someone may have some suggestions to help me. My engine won't take wide open throttle past about 7500 rpm. At that rpm the engine just suddenly slows, then leaps ahead, then abruptly slows again, then leaps ahead, etc. It feels like fuel starvation but it could be electrical. It is very abrupt with only some slight stumbling just before it starts the serious failure. It will run to redline if not too much throttle is given. The problem started suddenly and now does it every time I try to run toward the redline in all gears. The bike has 26,000 miles and for the last 4,000 miles it has an Akropovic ti pipe and ECU flash by 2WDW for the pipe. I have had no engine running issues prior to this. I did a service about 900 miles ago including plugs, air filter, valve check, and throttle body sync. I have checked for a kinked fuel line and any blockage of the airbox. There was no code shown on the dash and the check engine light has not come on. I've put it in diagnostic mode and there are no fault codes. There doesn't seem to be a fuel filter to replace other than one that is on the fuel pump so I can't just try a fuel filter without buying a new fuel pump. I have spoken briefly with 2WDW and they were helpful but we were not able to come up with a solution. I have done more diagnostic work since I spoke with them and I hope to speak with them again to see if they can point me in the right direction. For now, I don't know what to investigate. Thanks for any help. My guess would be a kinked hose under the airbox. I remember someone warning of that when performing a TB sync. Piedmont of NC '15 FJ-09 '94 GTS-1000 Link to comment Share on other sites More sharing options...
bobaintstoppin Posted April 6, 2016 Share Posted April 6, 2016 Mcride, Breakdown like this suggests several possibilities. Blocked air filter, fuel filter blocked or other fuel starvation such as kinked line etc, bad fuel pump. Since you recently did a tune up you should check the filter and air piping for issues. Also possible would be coils breaking down. Don't know if Yamaha has issues with coils or not. VW is known to have this on occasion, for example. Link to comment Share on other sites More sharing options...
skipperT Posted April 6, 2016 Share Posted April 6, 2016 All suggestions so far have been good. I would add: improper air filter or lid installation, not getting the clamps seated properly where the airbox meets the throttle body, or check to see if the throttle body assy itself has popped out of the intake. Older (04 or 05?) R6 models had an issue with ign coils arcing to the side of the spark plug cavity in the head, but no other models since then that I know of. Is it possible the foam near the airbox inlet under the front of the tank has gotten loose and is partially blocking airflow at the intake? Bad spark plug perhaps? Did you disconnect any other sensors that might not be plugged in all the way, or mixed up possibly? (Intake air pressure sensor comes to mind.) Keep us posted. Skip Link to comment Share on other sites More sharing options...
vespadaddy Posted April 6, 2016 Share Posted April 6, 2016 Older (04 or 05?) R6 models had an issue with ign coils arcing to the side of the spark plug cavity in the head, but no other models since then that I know of. Skip It was the 2003 R6. Yamaha replaced mine under warranty. Link to comment Share on other sites More sharing options...
thruster8999 Posted April 6, 2016 Share Posted April 6, 2016 To me this really sounds like the airbox is not attached to the throttle bodies correctly. Link to comment Share on other sites More sharing options...
mcride Posted April 11, 2016 Author Share Posted April 11, 2016 Thanks everyone for your suggestions. I think I have checked all your ideas except for fuel pump function. I removed the fuel pump to check for trash in the tank but it is clean inside and the pump screen filter is clean. My ECU is at 2WDW for evaluation which they have offered to do no charge. (You can't beat that customer service.) If they don't find a problem I will have to try a fuel pump. I have found a place which sells a pump for only $70 so that's not as costly as a new pump from Yamaha. I guess it is a rebuild kit more than a whole new pump but I think it will replace the moving parts which should be all I will need. I will report back whenever I get this figured out. Thanks again and if anyone has a further suggestion I would appreciate your input. I suspect it is something simple I am overlooking. Link to comment Share on other sites More sharing options...
desertfjr Posted April 11, 2016 Share Posted April 11, 2016 TPSs do fail sometimes. You could check the resistance across the TPS as the throttle is rotated. Link to comment Share on other sites More sharing options...
skipperT Posted April 12, 2016 Share Posted April 12, 2016 Easier still to check it in diag mode. At idle it will display a value around 14-18 which wil steadily increase to 94-100 when at WOT. Skip Link to comment Share on other sites More sharing options...
mcride Posted April 24, 2016 Author Share Posted April 24, 2016 Just a quick update on my engine problem. My Yamaha dealer gave me an ECU from a new bike to see if it would cure my problem. I rode for close to 500 miles over the last two days and I could not make the issue reappear. I ran it to high rpm with wide open throttle many times and it never missed a beat so the problem is in the ECU. I'll have to see if 2WDW can help me again now that I know it is the ECU. Link to comment Share on other sites More sharing options...
Premium Member wessie Posted April 24, 2016 Premium Member Share Posted April 24, 2016 Just a quick update on my engine problem. My Yamaha dealer gave me an ECU from a new bike to see if it would cure my problem. I rode for close to 500 miles over the last two days and I could not make the issue reappear. I ran it to high rpm with wide open throttle many times and it never missed a beat so the problem is in the ECU. I'll have to see if 2WDW can help me again now that I know it is the ECU. that's excellent service from the dealer but as you have had an ECU reflash, it is difficult to make a claim against Yamaha. Hopefully Nels will be able to recover the ECU. This signature is left blank as the poster writes enough pretentious bollocks as it is. Link to comment Share on other sites More sharing options...
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