Optimax 225 running very rough

[W2F a V-King]

A voltage drop test is easy to do, and will verify the integrity of any circuit, Positive side or ground side. They are tested separately. The tricky part is that the circuit being tested needs to be engaged. Or under a loaded, in operation state.

Here is a couple YouTube links to give you a visual understanding.

https://www.youtube.com/watch?v=xerAp9Yd53Y

https://www.youtube.com/watch?v=paw80mS_Kxg

I would try to verify the harness and power head circuitry, before plugging in a new or borrowed ECU, or computer. jmho.

Just form reading what is happening to your motor, it sounds like an intermittent circuit or ECU failure, whether it be a broken/loose wire touching enough to work until heat/vibration causes it to restrict current.

If you can rule out the harness and circuits, then all that is left is the suspect sensor, or the ECU.

In the case of verifying the circuit between a sensor and the ECU, you have to isolate the circuit. Unplug the sensor, and the main ECU connector. Locate the pin inside the ECU connector for the circuit you want to test and on the sensor side as well. Once identified...( just for grins, disconnect the battery for this to avoid crossing a hot wire to something not intended for battery voltage..ie. poke the wrong pin.)

Locating the circuit you want to test is not difficult. The sensor end is usually easiest to start with, attach one lead of your ohm meter (set on lowest scale) to the pin on that wire in the connector, on the ECU side connector it helps if you have a picture of the connector with labeled pins, or you can us the other lead of your ohm meter and touch the pins to find which circuit you want to test. If the circuit you are looking to test is an open circuit you will need wire color or pin location of the circuit in question, in the connector (or both) to locate the correct wire to find the break or corroded part.

Once you have the circuit isolated, run a few amps through it and wiggle/ pull/ stretch gently the harness while testing. You can load it easy enough by taking a headlamp or some 12V device that will draw a few amps (about 5 amps should be enough).. Wire it up so you can connect either the power side or the ground side of your headlamp to have to pass through the wire in your harness you want to test.

This may sound like it's a lot to do. But it is not really hard. And it is likely the path a marine technician would take to correct your concern, save for the part that they would likely have "known good test parts" to help.

HTH

James

[flabum1017]

I had one acting strange like that a few years ago, turned out the flywheel splines were stripped, probably from a loose flywheel or sudden stop syndrome (hitting a log or something)..............

[Martin_80]

Thanks James!

I've checked the flywheel, at least it feels like there is no problem.

I've looked at the alternator and even started the motor without it connected but there was no different.

Im hoping to get a hold of another ECM to try.

[Martin_80]

I got hold of a used 225 ECM to try and the problem went away. I've run the engine three times and a couple of hours... My ECM is bad!

Does anyone have any knowledge or experience of repairing a ECM? I doubt that anyone can change out electrical components in these since from memory all components are blank and you would most likely have do destroy the lid to get inside. There are some who claim that they can fix some issues, would that be more in the nature of programming/re flash? What do/can they do?

[Euroski]

I would call Simon MotorSports and ask.
760-440-9334

[Martin_80]

I will contact them, I'm curious about others who had similar problems and what the solution where.

[endofline]

Martin80, did you get your problem fixed?

Not that I'm qualified, I'm an automobile mechanic. I recently had a CPS fail on my 2.5L 150hp but it didn't show up on the DDT when running automatic scan with key on. I couldn't do a running scan as the engine wouldn't start.

If it was a car, I would suspect a dirty TPS or two. Volvo produced early canbus cars (99-01) with Marelli throttle modules that had two built-in throttle reostats to tell ecu the throttle position. These ultimately failed, leading to inability to accelerate without setting a code. Volvo wound up with a class-action suit on their hands.

Please post a resolution.

Thanks, Steve

[flabum1017]

Martin80, did you get your problem fixed?

Not that I'm qualified, I'm an automobile mechanic. I recently had a CPS fail on my 2.5L 150hp but it didn't show up on the DDT when running automatic scan with key on. I couldn't do a running scan as the engine wouldn't start.

If it was a car, I would suspect a dirty TPS or two. Volvo produced early canbus cars (99-01) with Marelli throttle modules that had two built-in throttle reostats to tell ecu the throttle position. These ultimately failed, leading to inability to accelerate without setting a code. Volvo wound up with a class-action suit on their hands.

Please post a resolution.

Thanks, Steve

He had a bad computer

[Martin_80]

Yes that is correct. I have a "new" ECM on it's way, I hope to be able to try it before winter.