View Full Version : Tonyaus need more help with 225 Yamaha

m. young
04-27-2004, 04:12 PM
" Thanks tonyaus for the info. My 225 Yamaha (1988 Excellg) is a YMIS. I have checked all my sensors and they check good. The throttle position sensor is reading 20/1000/1000 ohms as the book states it should. Still leaning towards fuel starvation. I pulled my fuel line off of the top carb and when spinning it over it has a kinda weak pulse action. I also pulled that line while running the motor (I know) and it's kinda steady but weak looking again. How much pressure or flow should my fuel pumps put out, I know it not much pressure wise. Remember, when I choke it, it gets up and goes again. I have cleaned and checked carbs, plugs, you name it. Runs great as long as I am cruising. Thanks again, Mark "

04-29-2004, 05:48 PM
YMIS.....these can be fun. One of my customers had 2 of these and i learned a hell of alot about them. Now back to your situation. From memory you are having acceleration problems. If you are sure your carbs are spotless (particularly the high speed jets) I would be looking closer at the throttle position sensor. Those readings sound right even though I dont have my book in front of me. The other thing about that sensor is its adjustment. I dont remember which way to move it but if you can move it slightly towards the way that would show the computer slightly less throttle that should cure your problem. In regards to your fuel pump while you are idling are you getting raw fuel dumped in the water? If not then your diaphrams are ok. As far ar pessure goes have someone applying pressure to your pimer bulb while you drive the boat. If there is no change then your fuel pumps are ok. It might also pay to put a timing light on the motor just to make sure the timing is advancing. Let me know what you find.