1990 Yamaha 225 2.6l

[oceanrunner28]

Hello, My 1990 225 yamaha will not go over 3,000 Rpm. My stator, fuel pumps, carbs,crank sensor,fuel line and filters seems to be good. I have 120 and spark in all six cylinder. I start my motor up every week all year long, What else should I look for? can it be the thermo sensor,TPS or knock sensor? Please, e-mail me at oceanrunner28@aol.com with any tips. Thanks for your help.

 

[rodbolt]

Re: 1990 Yamaha 225 2.6l

what tests have you run to verify the "seemingly good" parts?

 

[oceanrunner28]

Re: 1990 Yamaha 225 2.6l

I checked the stator with a OHM meter and is on specs, I opened the carbs and fuel pumps and they are clean.

 

[Ray Neudecker]

Re: 1990 Yamaha 225 2.6l

You can do a basic test on the TPS with your ohm meter. Disconnect and hook to the two wires, move the throttle manually and see if you have open spots. It is simply a variable reistor. The thermo sensor should set off the horn if overheating. Disconnect the non ground side and with the switch on ground it. The horn should go off then. Test the knock sensor by disconnecting the lead to it and seeing if engine responds. The TPS is the only part which is a more often failure item. You can also check the TPS by advancing the throttle with the use of a timing light to see if it is advancing. If these check OK then a fuel restriction is the most likely cause.

 

[oceanrunner28]

Re: 1990 Yamaha 225 2.6l

Thanks for the information. Can The TPS,knock sensor or thermo sensor cause the motor not to go over 3,000 RPM'S

 

[Ray Neudecker]

Re: 1990 Yamaha 225 2.6l

The thermo sensor should limit to 200o Rpm's. The other two affect timing and may or may not depending on the weight of the boat ect. Check compression, then use a timing light to check fire and timing. If they check OK, then you are back at a fuel restriction, which I would suspect is the problem.

 

[oceanrunner28]

Re: 1990 Yamaha 225 2.6l

I Disconnect the thermo sensor non ground (pick wire) side and with the switch on ground it. The horn Did not go off. Does this mean that both sensor are bad? I took the boat out on Sunday and it ran at 4,500 RPM can it be a bad thermo sensor thats not letting it hit 5,500 RPM

 

[Ray Neudecker]

Re: 1990 Yamaha 225 2.6l

Not likely thermo sensors are both bad. It may mean the horn is bad. If the system was working properly it would not allow you to run 4500 with a system protect alert. It certainly has all of the symptoms of a fuel restiction problem. There are many complicated to trouble shoot systems on that engine. I would reccomend you turn it over to someone who has experience with trouble shooting that engine and system. This is where the experienced service technician can save you a blown power head.