Hello group,<br /><br />Here is the problem I am experiencing with my Yamaha Pro 50 LT and what I have done so far to try and fix it.<br /><br />The motor runs fine for about a minute or so at approximately 3/4 throttle or so then when it starts to lose power you must back off all the way to idle or it will die. You need to back off and stay at idle for about 20-30 seconds when this occurs or it you cannot regain full power. Running at half throttle you will be fine and no problems will occur. <br /><br />Here is what I have done so far, need to do, conversations I have had and my speculation of a possible solution. <br /><br /><br />Compression test on all 3 cylendars (Approx 125psi each)<br />New fuel fines to motor<br />New fuel bulb<br />New fuel/water separator<br />New plugs<br />Carb cleaner<br />New fuel pump<br /><br />A person that I know who races boats had suggested a possible fuel problem that may have to do with an air leak in line, defective fuel bulb or a defective diaphram in the fuel pump. I replaced the pump and the hoses and bulb are new though that is still a possability I guess since I did not try a second new fuel bulb or replace lines again.<br /><br /><br />I expected the other day that I would have had better luck as the old fuel pump diaphram rubber was a bit flexible when I took it apart though no holes etc. but no joy and the same symptoms occured even with the new updated version of the pump. <br /><br />Since that failed I decided to check the choke switch this while running and as the engine started to die as usual under full power when flipping the switch things got better real fast. I am very confident this is directly related to the problem but let me go further and tell you what I suspect. <br /><br />If you hold the choke switch things will get better real fast for about 30 secs or so and then the motor will die down or stall. Without having taken the controls apart and having some electronics background as well I strongly suspect there is a large resistor or other electronic component/sensor in the controller or on the motor itself that is heating up and failing. A classic thermal problem. <br /><br />Perhaps something with a heat sink or whatever. I really don't want to try and dissassemble the controls and find just a switch there when what I am looking for may be located on the motor itself right in front of me but I would guess it may be either a component in the controller or a sensor on the motor. <br /><br />Can anyone help confirm my suspicions of failed electronics components here or a failed sensor on the motor itself that controls the choke.<br /><br /><br />Other than investigating that scenario which seems most likely my next choice would be to confirm the new fuel bulb and new fuel line as being defective or not then opting for a carb rebuild.<br /><br /><br />I am not familiar with outboards at all other than motor basics so any help would be appreciated.<br /><br /><br />Your thoughts?<br /><br /><br />Thanks in advance for any relies!<br /><br /><br />Art<br /><br /><br />My email is art@vestport.com
