200 HPDI - 2004 - Revs up without power

Hi all, I just found this forum and glad to be a part of it!

I have a 2004 HPDI 200 hp. I have an intermittent problem. SOMETIMES, after putting the engine in gear and pushing the hotfoot, the engine will rev with very little power. It almost sounds like it is a 9.9 hp revving up. I understand that these engines only idle on 4 cylinders, but the sound when having the issue is almost like more cylinders are shutting off. I can normally correct the problem by shifting back in neutral 2 or 3 times. Once going, she runs strong all the way to top end. The same symptoms often occur again when coming off of plane and juicing a little to keep the back deck dry.

Does anyone have any suggestions about this? Again, this doesn't happen all of the time. I don't have a local Yamaha dealer, so any help is greatly appreciated. THANK YOU!

email: bryan.kusic@yahoo.com 412-877-0492 cell.

[Hamfisted]

Test the neutral / safety switch...

Possible the neutral / safety switch is going bad. Its there in the shift linkage track right where the cable joins the shift linkage pin. Do you have a service manual for your motor?



- Mike

ranger had this same exact problem on same engine. Take off the cover so you can see your cyliners and the air intake flaps. have a buddy stand back there and gear it in forward and reverse. my guess is when you have it wide open and then come back to neutral or there boughts the flaps are closing all the way and your getting air around them thus the reviving up thing. My problem was actually a loose screw on the gear shifter. just check the whole gear shifter rod system out and see if you have any loose areas. the vibrations overtime i've found loosens some of these up preventing a complete closure the air intake flaps. once i found my loose screw my idle high problem disappeared. where i was idling up to around 13 rpm before it went back down to a quite 6. good luck hope this helps.

Thanks guys.

Hamfisted: Is the neutral / safety switch the same as the throttle position sensor? I do NOT have a service manual for this engine.

pdstephe: Maybe I didn't explain this in enough detail the first time around. The engine doesn't rev on its own at idle or in neutral. It's when I push the hotfoot to get power, and all I get are revs with very little power.
Bryan