2001 Yamaha F225 4 stroke WOT probs

[smangold]

I am currently having problems with upper rpm range with a 2001 Yamaha F225 4-stk motor.<br /><br />Idle and mid range fine.<br /><br />Misses, stalls, hunts, fluctuates, etc are the best way to describe prob at 3600rpm & above.<br /><br />Can milk to steady 4000 with the help of the portside LF 225 outboard. Try to push it further it drops back to 3600.<br /><br />Yamaha YDS shows no codes or faults.<br /><br />Rans tests in YDS..........okay<br /><br />Ran on test fuel tank connected to LP fuel pump intake...Still prob.<br /><br />Verified prob not in the ECM.<br /><br />Injector ohmic values check.<br /><br />I have a LF 225 on same vessel.<br /><br />Have swapped some of the modules, sending units, etc that are passive and do not req. calibration.(ie intk press sender, oil press sender, etc). <br /><br />Did not swap TPS as I didn't want to mess with the synch/link.<br /><br />Still have problem.<br /><br />Any suggestions..........

 

[seahorse5]

Re: 2001 Yamaha F225 4 stroke WOT probs

Per the manual, hook up a fuel pressure gauge to the injector rail and run the motor. Chances are the pressure drops off due to a faulty reguator, weak or bad electric pump, or a plugged screen.<br /><br />Also, these 4 strokes carbon up and stick valves or rings if Ring Free is not used consistantly and you do a lot of trolling, contrary to popular belief. Normally, it shows up as poor low speed performance. You might have your tech perform a cylinder leakdown test to check the conditions internally.

 

[smangold]

Re: 2001 Yamaha F225 4 stroke WOT probs

Thank you for the input.<br /><br />However, the only port that I could find for measuring the fuel pressure (both physically and in the manual) was at the vapor separator schraeder valve, which is on the low pressure side.<br /><br />As it turns out it was the high pressure fuel pump filter screen at the bottom of the hp pump which is located within the vapor separator. It looked as if some algae, varnish, or some other type of funk accumulated here.<br /><br />I was apprehensive of dismantling the vapor separator due to warranty concerns. However, since it is so dificult in getting a factory rep to diagnose and repair dockside in my area, I went for it. <br /><br />Again, thanks for the help.<br /><br />smangold<br />marine machinist

 

[Forktail]

Re: 2001 Yamaha F225 4 stroke WOT probs

Way to go smangold! <br /><br />You may want to change the fuel filter/water separator, drain the fuel tanks, or at least add a fuel conditioner/treatment to keep it from happening again.

 

[seahorse5]

Re: 2001 Yamaha F225 4 stroke WOT probs

That is a very common problem on motors that are used infrequently.<br /><br />You hooked things up correctly and found the problem. Congratulations!