Rodbolt (225HP Yamaha OX66 Issues)

[msu202020]

Have a problem. Motor is a 2000 Yamaha OX66 225HP, SX225TXRZ.

Today I put the boat in the water, and it seemed to idle a little rough, sort of had a shutter to it. When I went to put it on a plane the motor seemed to surge to about 2900 rpms and stay there. After about 5 seconds, it would jump up to normal RPM range and hold. Granted, I didn't run it very long above 4000 rpms, only a couple of seconds.

My questions is, where should I start to diagnoise the problem?

I did the following for preventive maintenace this fall:

Changed all three Low Pressure Fuel Pumps
Changed all the plugs
Changed the ball
Changed the water separator
Cleaned the screen inside the Vapor Separator Tank
Cleaned the O2 Sensor

Thanks for the help.

 

[msu202020]

Re: Rodbolt

Re: Rodbolt

Bump

 

[msu202020]

Re: Rodbolt (225HP Yamaha OX66 Issues)

any ideas? I want to hit this from a systimatic approach, not just a change parts approach.

 

[cousinabe]

Re: Rodbolt (225HP Yamaha OX66 Issues)

I would hook up a winky blinky and a fuel pressure gauge to the vst and monitor both while motor is surging.

 

[rodbolt]

Re: Rodbolt (225HP Yamaha OX66 Issues)

kinda what cousin abe says but I would add to test the O2 sensor voltage output as well as testing rail pressure at the problem RPM.
I dont care if the O2 sensor is clean or dirty, I do care about the voltage feedback to the ECU.

 

[msu202020]

Re: Rodbolt (225HP Yamaha OX66 Issues)

Appreciate the info Rodbolt, so check O2 sensor output voltage at 2900 rpms while it is struggling to get up on a plane?

Rodbolt, where is the best place to get a test harness from?

KennyB

 

[msu202020]

Re: Rodbolt (225HP Yamaha OX66 Issues)

One more thing, what exactly should I be looking for in a Rail Testing Gauge? I have the test harness.

 

[rodbolt]

Re: Rodbolt (225HP Yamaha OX66 Issues)

fuelpressure must stay about 35PSI at all times.
on the O2 sensor your looking for a scaling voltage between about .3 and .6V.

 

[msu202020]

Re: Rodbolt (225HP Yamaha OX66 Issues)

fuelpressure must stay about 35PSI at all times.
on the O2 sensor your looking for a scaling voltage between about .3 and .6V.

Rodbolt, the winky blinky is showing a code 18 for the TPS, tested the fuel pressure on the muffs and it stayed at 35 psi. I am going to put the boat in the water and run it today and monitor the fuel pressure. I still haven't gotten the harness for the O2 sensor, but working on it.

Also, I played around with the TPS and when I did the winky blinky would sometimes throw a code 32.

 

[rodbolt]

Re: Rodbolt (225HP Yamaha OX66 Issues)

32 isnt used but 33 indicates the ECU sees the engine below 113 degrees.
cold.
18 means the ECU sees the TPS feed back out of range.
test the TPS 5V reference,orange to black, the the TPS pink to black.
if the 5V is out of range ther feed back will follow it.
any orange wire under the hood is 5V reference and any sensor can take it down.
winky only shows 1 code at a time and then only the lowest code number first.

 

[msu202020]

Re: Rodbolt (225HP Yamaha OX66 Issues)

Rodbolt, my book is showing a code 32 for a shift control shutoff? Also, ran the boat and it held 35 psi. I need to test the TPS and the O2 Sensor now.

Also, played around with the TPS, now the motor seems to idle fine, but when put it in gear or fast idle it bogs down.

 

[rodbolt]

Re: Rodbolt (225HP Yamaha OX66 Issues)

what book are you using?

 

[msu202020]

Re: Rodbolt (225HP Yamaha OX66 Issues)

Unfotunately I am using the Sealock. I know I need to get the Yamaha book.

 

[Asainz320]

Re: Rodbolt (225HP Yamaha OX66 Issues)

I bought the yamaha manual on ebay for $10 in a CD. Its awsome, you should get it too. I started using a sealoc manual as well and it was not as good and as acurate as the yamaha manual.

 

[msu202020]

Re: Rodbolt (225HP Yamaha OX66 Issues)

Rodbolt,

I did verify, the winky blinky is throwing a code 32. Three blinks, then two blinks.

 

[rodbolt]

Re: Rodbolt (225HP Yamaha OX66 Issues)

everything I can find about code 32 is its microproccesor information and not used for troubleshooting.

 

[msu202020]

Re: Rodbolt (225HP Yamaha OX66 Issues)

ok, appreciate the info Rodbolt. I have it at the shop, waiting to hear back on what they say. I know for sure I was throwing a code 18 and that I was holding fuel pressure. I still haven't gotten the harness to test the O2 Sensor.