91 Yamaha 225TXRP Loses RPM's

[mvbeachbum]

My engine starts and runs fine up to about 7-10 knots. When I accelerate, it goes fine initally then the engine just reduces the RPM's. My temp gage is normal and the oil gauge is green and oil level is fine. On some occasiions the alarm will sound, but not always. When I come back to netural I can repeat the process. Sometime it will stay at the high speed longer than others, but never more than 2-3 minutes.

 

[rodbolt]

Re: 91 Yamaha 225TXRP Loses RPM's

after doing a compression test I would replace the fuel pumps and if your model has the primer pump assy replace the diaphram in that one then clean the carbs. make sure the t-stats are working properly.borrow the test harness to check the TPS or keep a timing light on it to see what the ign timing is doing when the motor slows.<br /> good luck and keep posting

 

[mvbeachbum]

Re: 91 Yamaha 225TXRP Loses RPM's

compression was even on all cylinders, replaced both fuel pumps. Carbs are clean and just rebuilt. I don't know if I have a primer pump.I was wondering if I had a bad sensor. Thanks.

 

[hwiegert]

Re: 91 Yamaha 225TXRP Loses RPM's

Originally posted by mvbeachbum:<br /> compression was even on all cylinders, replaced both fuel pumps. Carbs are clean and just rebuilt. I don't know if I have a primer pump.I was wondering if I had a bad sensor. Thanks.

 

[hwiegert]

Re: 91 Yamaha 225TXRP Loses RPM's

Originally posted by mvbeachbum:<br /> compression was even on all cylinders, replaced both fuel pumps. Carbs are clean and just rebuilt. I don't know if I have a primer pump.I was wondering if I had a bad sensor. Thanks.

Sounds just like the problem I encountered over Thanksgiving. My motor is a 2002 C40Y 3 cylinder 2-stroke outboard with about 50 hours runtime. My guess is that the problem is fuel starvation. The fuel filter checked clean and I am replacing my fuel line with primer bulb next (the primer bulb is that thing (bulb) that you are supposed to squeeze several time to get fuel to the engine). After this it is new spark plugs - even so they still look good. Probably should have done it the other way around since the plugs are cheaper. But it does not hurt to have spare plugs. If this does not work, I am looking at the ignition system. I checkked the boat about 10 days prior to taking it out and when putting the cover on I inadvertantly turned the ignition on which also caused my run-hour meter to run up about 200 hours. Other basics I have checked were the strainer in the fuel tanks (i have two tanks and it happens on both of them)and that the fuel is not gunking up. I used fuel stabalizer year round, but will now only get premium gas since this does not gunk up (according to a Chemical Engineer at work).<br />I hope to check it out in the next few weeks and will let you know my results - if any!