F225TXRD 2005 ECM problem???

[LenTaft@yahoo.com]

I have a 2005 F225TXRD that began running very rough above 2000 rpm until warmed up, then smoothed out to all rpm. This condition slowly got worse, requiring longer warmup time, and no longer just first start of the morning, but now every start. I have had this looked at by certified Yamaha service center several times. They believe the problem "MAY" be a $$$ Electronic Control Module. This last week, the condition began an exponential decline. It now is hard to start, must be placed in neutral to throttle up just to continue firing, but incapable of more than 1500 rpm. only luck and perseverance gets motor in gear without dying, and then a slow, rough, 1400 rpm ***** to shore. Mechanics have gone over fuel system. I have elaborate fuel filtration system and external fuel boost pump because of bad island gasoline. I have added injector cleaner and water-zorb to the fuel.

My internet search suggests dirty injectors, Throttle Position Sensor, stuck thermostat, air leak from fuel primer bulb, Idle Speed Control valve, and Variable Valve Timing pulley, as possible causes. Are any of those valid? or red herrings??

Please tell me what tests my mechanic can perform to positively identify the problem. Are there sensors that can be sending bad info to a good ECM to produce these symptoms, or is the ECM the only possible culprit?

Thank you for any insight. I am desperate.

[Sequoiha]

Food for thought, I have been doing this for over 30 years, I can count on 1 hand the ECM 's I have replaced,

[pstephens46]

Bad Island Gasoline sounds fishy!

[boscoe99]

Seen it a million times.

It is always the variable valve timing pulley. On the exhaust side.

[boscoe99]

By the way, what is the voltage on the orange wire from the ECU?

[99yam40]

Seen it a million times.

It is always the variable valve timing pulley. On the exhaust side.

is this part of the Drano logic or are you just pulling his leg.
hard to tell without something extra on the end

[boscoe99]

is this part of the Drano logic or are you just pulling his leg.
hard to tell without something extra on the end

You got me.

An F225TXRD does not have variable valve timing. For either the intake or the exhaust valves.

Variable cam shaft timing was introduced with the F250. But only for the intake cam shafts.

Maybe a few HPDI's had it before then but they are irrelevant for the purposes of this thread.

[99yam40]

Well I did not pay that much attention since he mentioned valve timing

[LenTaft@yahoo.com]

Thank you for all responses. I am pursuing every suggestion. This Yamaha powers the tender to a VERY busy charter boat, and I cannot afford any down time. I really appreciate any additional thoughts/guidance from the benevolent experts of this forum. Thank you.

[rodbolt17]

finding a real tech in your area may be difficult.
but I highly doubt a failed ECU.
has the fuel rail pressure been checked?
have the spark plugs been tested using a Kv tester?
does your tech have access to YDS or at least the diagnostic test lamp?