2012 F250 Won't Go Over 3000 RPM

[morassra]

A few weeks ago, I was out fishing, and my 2012 F250 4-stroke started to lose RPMs, without any corresponding change in throttle position. On the way back to the dock, it threw a temperature alarm, and would not accelerate past 3000 RPMs.

Since then, we have checked all of the filters, fuel pressure, the fuel itself, and anything else we can think of. Everything seems fine, except my brand new spark plugs (3 weeks old?) were blackened, as if the engine is running rich. No new alarms. We still can't get it to run past 3000.

It's now with my Yamaha mechanic. He's baffled. The engine has less than 300 hours on it, and has been serviced meticulously, and always dosed with Ring Free at fuel-up.

Any input would be appreciated.

[stuff2c!]

I had a similar issue with my F115 I tried everything then cleaned the injectors and it has been fine ever since.

I cleaned them using a method I found on YouTube. wasn't really that hard once I found the right syringe to fit the injector.

here is the link https://www.youtube.com/watch?v=7aT4S1lIBAY

[greasyshaft]

Model code?

[morassra]

It's a 2012 F250XA.

Update: The engine is running, but will not consistently accelerate past 3000 RPMs, though my mechanic did get it to 4600 yesterday at one point.

Now he's leaning toward a bad/clogged injector(s). I'm concerned that cleaning them may affect my warranty, and my Yamaha mechanic doesn't think any of the work will be warrantied, because Yamaha is going to blame it on ethanol.

Compression tests, and further investigation, to come this morning.

[rodbolt17]

do yourself a favor.
please find a real tech.
that issue should take about 45 min to find.
its as simple as observing rail pressure and the laptop at the failure RPM and load.
then you know what filter clogged.
its a stupidly simple speed density EFI setup.
it will try to troubleshoot itself.
if rigged with command link you can access trouble codes on the tach.

[morassra]

I don't have Command Link gauges.

[morassra]

It's a blown powerhead. A new one is on its way from Yamaha. Yay.

[99yam40]

Just exactly what was the problem that you would call a blown power head?

[morassra]

The exact details are still a little unclear. I'll know more today. I know that the flywheel is lifting off the top of the powerhead, and the engine is knocking something fierce. Timing is way off. When the tech contacted Yamaha, they immediately shipped out a brand new powerhead.

[99yam40]

You did not say anything about it knocking before, just would not go over 3K in RPMs.

and what do you mean the flywheel is lifting off the top of power head?

[boscoe99]

Sounds like a failed thrust bearing. When the bearing goes the flywheel can be lifted up quite a bit more than is normal.

People don't tell us their models and apparently don't tell us the full story when they come looking for help.

"Oh, I forget to mention that the motor had a rod flying out of the block when it would not go over XYZ RPM. Do you think that might be part of the problem?"

[morassra]

Sometimes people don't know the full story. The model number is posted above.

[Livinlinelife]

Please correct me if I'm wrong but I think this is worse than a blown alternator.

[Livinlinelife]

Dose this happen often?

[rodbolt17]

only when the alternating electrons cant go forward.
then it all turns to sheet.
yes SOME not ALL 4.2L v6 motors had an issue that wiped out the thrust bearing.
some have issues with water backing up the ex and bending rods.
some airplanes seem to disappear.