A Friend's OptiMax Problems Uncured by Mercury Specialists

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Author Topic:   A Friend's OptiMax Problems Uncured by Mercury Specialists

nisse posted 08-09-2008 04:26 PM ET (US)
Hi everyone. A friend of mine has a 2003 Mercury Optimax 90. It has only run about 50 hours and she has a problem that all Mercury specialists have not been able to solve. [The 2003 Mercury Optimax 90] starts and idles fine. I can start running at below 3,000-RPM for five minutes just to leave the harbor. When opening the throttle the engine reacts fine at first. It runs OK for some minute (even at high RPM) and then suddenly looses all power. If I throttle down to half, it can resume normal running, but not always.
I have found that if I am running at about 3,000-RPM and starts to tilt the engine up or down just a little it can start to oscillate wildly, changing its speed between 2,000 and 3,000-RPM just like going on-off-on in a rapid pattern. The only way to get rid of it is throttling down to idle.
When the engine starts to go badly, the high pressure fuel pump (I think it is that in the port side alloy box with the fuel pump on, and fuel lines to the fuel rail) to sound badly, it is making a squeeking noice. If it is sounding like this because it is lacking fuel, or if the fuel pressure goes down because of a faulty pump.
I have also some strange things on the SmartCraft Gauge. It has 4 warnings: PITOT, TRIM, FUEL EMPTY and OIL EMPTY. When scanning the different readings I get 0 in speed, 0 in oil temperature and 0 in oil pressure. In reality, the oiltank is full, the fuel tank is half and I am making a good 25-knots. I have no manual to check what these warnings mean.
To this date my friend had payed over $1,500 to a Mercury service center, but no difference. The engine is still not working. They have cleaned tanks, changed fuel lines, filters, etc, but seem to not know what to do.
I think it is either a fuel problem or a sensor problem that tricks the ECM to handle fuel incorrectly.
Does anyone have an idea, I know a lot of engines, have designed my own EFI-system etc, but I do not know that much about this particular engine.
I hope someone can give me a clue.
Best regards
Nisse / Sweden
jimh posted 08-10-2008 10:43 AM ET (US)
You report that the onset of the problem is coincident with operating the electrical trim on the motor. My conclusion is that the problem is likely electrical in nature. I explain:
When the trim motor is operated it draws substantial current from the vessel electrical system. If the storage battery is not in proper condition it will not maintain its voltage at 12.5-volts or higher. The OptiMax motor is known to be sensitive to the voltage of the electrical system.
Also, the occurrence of so many warnings on the SmartCraft gauge which seem to be unrelated to the engine malfunction also speak to an electrical discontinuity.
Give the boat electrical system a careful examination. The battery should be fully-charged and have ample reserve capacity. Check for any loose connections in the primary battery distribution wiring, particularly in the battery negative terminal to engine block connection and in the primary battery positive terminal distribution wiring.
jimh posted 08-10-2008 10:56 AM ET (US)
Also--check the ground circuit path for the trim motors. If there is a poor connection somewhere, the current for the trim motors may be flowing via an unintended path. Flow of current where it is not intended may be causing electrical problems.
nisse posted 08-10-2008 12:18 PM ET (US)
Hi
Thanks!
I will check all the electrical carefully
Nisse
Lars Simonsen posted 08-10-2008 04:44 PM ET (US)
I agree with Jim. The fuel pump requires a lot of voltage, and even on an optimax that is running well, at lower RPM, actuating the trim motor will reduce the RPM (due to the additional electrical load). When the alternator on an optimax starts acting up, the motor does strange things, like sudden precipitous drops in RPM, etc. Mine doesn't have smartcraft, so I don't know what kind of strange codes a dying alternator might cause, but the symptoms you describe definitely sound electrical, and one thing to look at is your alternator.

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Author	Topic: A Friend's OptiMax Problems Uncured by Mercury Specialists
nisse	posted 08-09-2008 04:26 PM ET (US) Hi everyone. A friend of mine has a 2003 Mercury Optimax 90. It has only run about 50 hours and she has a problem that all Mercury specialists have not been able to solve. [The 2003 Mercury Optimax 90] starts and idles fine. I can start running at below 3,000-RPM for five minutes just to leave the harbor. When opening the throttle the engine reacts fine at first. It runs OK for some minute (even at high RPM) and then suddenly looses all power. If I throttle down to half, it can resume normal running, but not always. I have found that if I am running at about 3,000-RPM and starts to tilt the engine up or down just a little it can start to oscillate wildly, changing its speed between 2,000 and 3,000-RPM just like going on-off-on in a rapid pattern. The only way to get rid of it is throttling down to idle. When the engine starts to go badly, the high pressure fuel pump (I think it is that in the port side alloy box with the fuel pump on, and fuel lines to the fuel rail) to sound badly, it is making a squeeking noice. If it is sounding like this because it is lacking fuel, or if the fuel pressure goes down because of a faulty pump. I have also some strange things on the SmartCraft Gauge. It has 4 warnings: PITOT, TRIM, FUEL EMPTY and OIL EMPTY. When scanning the different readings I get 0 in speed, 0 in oil temperature and 0 in oil pressure. In reality, the oiltank is full, the fuel tank is half and I am making a good 25-knots. I have no manual to check what these warnings mean. To this date my friend had payed over $1,500 to a Mercury service center, but no difference. The engine is still not working. They have cleaned tanks, changed fuel lines, filters, etc, but seem to not know what to do. I think it is either a fuel problem or a sensor problem that tricks the ECM to handle fuel incorrectly. Does anyone have an idea, I know a lot of engines, have designed my own EFI-system etc, but I do not know that much about this particular engine. I hope someone can give me a clue. Best regards Nisse / Sweden
jimh	posted 08-10-2008 10:43 AM ET (US) You report that the onset of the problem is coincident with operating the electrical trim on the motor. My conclusion is that the problem is likely electrical in nature. I explain: When the trim motor is operated it draws substantial current from the vessel electrical system. If the storage battery is not in proper condition it will not maintain its voltage at 12.5-volts or higher. The OptiMax motor is known to be sensitive to the voltage of the electrical system. Also, the occurrence of so many warnings on the SmartCraft gauge which seem to be unrelated to the engine malfunction also speak to an electrical discontinuity. Give the boat electrical system a careful examination. The battery should be fully-charged and have ample reserve capacity. Check for any loose connections in the primary battery distribution wiring, particularly in the battery negative terminal to engine block connection and in the primary battery positive terminal distribution wiring.
jimh	posted 08-10-2008 10:56 AM ET (US) Also--check the ground circuit path for the trim motors. If there is a poor connection somewhere, the current for the trim motors may be flowing via an unintended path. Flow of current where it is not intended may be causing electrical problems.
nisse	posted 08-10-2008 12:18 PM ET (US) Hi Thanks! I will check all the electrical carefully Nisse
Lars Simonsen	posted 08-10-2008 04:44 PM ET (US) I agree with Jim. The fuel pump requires a lot of voltage, and even on an optimax that is running well, at lower RPM, actuating the trim motor will reduce the RPM (due to the additional electrical load). When the alternator on an optimax starts acting up, the motor does strange things, like sudden precipitous drops in RPM, etc. Mine doesn't have smartcraft, so I don't know what kind of strange codes a dying alternator might cause, but the symptoms you describe definitely sound electrical, and one thing to look at is your alternator.