Yamaha F250A 6P2 – Code 72 Above 4000 RPM After Warm-Up

[taka]

Hello everyone,

I have a Yamaha F250A (6P2) and I am trying to diagnose an intermittent engine warning.

The problem occurs after the engine has warmed up and I run it above approximately 4,000 RPM.

Most recently, I was cruising normally at about 4,200 RPM when the engine suddenly dropped to around 3,700 RPM. Immediately after the RPM dropped, the engine warning indicator started flashing.

The warning flashes 7 times, pauses, then flashes 2 times. I believe this may indicate code 72, but I would appreciate confirmation from anyone familiar with this engine.

There is no warning buzzer.


After the warning occurs, if I try to run the engine above 4,000 RPM again, the RPM becomes unstable. It will rise and fall instead of staying steady.

Also, after the warning occurs, when I return to neutral, the idle speed is around 800–900 RPM, compared with the normal idle speed of approximately 600 RPM.

If I stop the engine and restart it, the warning disappears and the idle returns to approximately 600 RPM.

However, once the engine is already warm, the same problem seems to occur sooner when I run above 4,000 RPM again.

Parts replaced or swapped​

• Swapped the PORT and STBD cam position sensors – no change in the problem.
• Swapped the PORT and STBD OCVs (Oil Control Valves) – no change.
• The OCV filters were swapped together with the OCVs – no change.
• Engine oil was recently replaced.
• Engine oil filter was recently replaced.
• Thermostats have been replaced.

Checks already performed​

• Fuel filter visually inspected – no obvious problem.
• OCV resistance checked – both sides were approximately the same.
• Cam position sensor connectors inspected – no obvious corrosion or loose connections.
• Cam sensor circuit voltages checked.
• Set the engine to 1TDCand checked the cam timing marks:
  • PORT side II–II marks align correctly.
  • STBD side I–I marks align correctly.
• Timing belt tension checked – no obvious looseness.
• Timing belt tensioner visually inspected – no obvious problem.

The engine otherwise starts easily and runs normally at lower RPM.

Because the fault consistently appears after warm-up and while running above 4,000 RPM, I am wondering if this could be related to the VCT system, oil passages, or another problem that only appears under sustained higher-RPM operation.

What would you check next?

Any advice from someone familiar with the Yamaha F250A / 6P2 would be greatly appreciated.

Thank you.

 

[boscoe99]

Are you talking about the warning coming from the tachometer?

Where on the tachometer are you seeing this?

 

[taka]

Yes. It is the engine warning icon in the upper right of the tachometer shown in the photo.
It flashes 7 times, pauses, then flashes 2 times.

I have been assuming that this indicates code 72. Is that correct?

 

[99yam40]

do you know what code 72 means?
i would be looking that up if I thought my motor was sending that code.

 

[taka]

do you know what code 72 means?
i would be looking that up if I thought my motor was sending that code.

Yes. According to the Yamaha service manual, code 72 is related to the PORT intake cam position sensor / signal.

That is why I swapped the PORT and STBD cam position sensors, but the problem remained on the same side.

I also swapped the PORT and STBD OCVs and OCV filters, with no change.

My main question is whether 7 flashes, a pause, then 2 flashes on this tachometer actually indicates code 72.

 

[boscoe99]

That tachometer does not provide fault codes.

You will need either YDIS of the winky blinky to get any codes that may be set.