Re: Pro-line
Do some research on early Optimax engines. Be warned that until 2002, Mercury was fighting numerous issues with Optimaxes. I walked from a deal years ago on 2001 Fountain with Optimaxes after research and seasoned boaters warned me. From my prior research:
When buying a used OptiMax engine, especially those made until the high-water mark of problems in 2002, it is important to verify that the engine has been upgraded in accordance with field service bulletins. Mercury has issued field service bulletins on the OptiMax engine to correct a number of problems.
The OptiMax engine has an engine control module (ECM) that can provide some information about the engine's operational history, but, unfortunately, this data is locked up in a proprietary format and can only be accessed by a proprietary code reader tool. This expensive tool, a DIGITAL DIAGNOSTIC TERMINAL (DDT) (P/N 91-823686A2) is generally only available to certified Mercury mechanics. You should consider locating a mechanic (who is independent of the seller or selling dealer) who can access the engine data and give you a print out. Our ask the seller to provide this as a condition of the sale, subject to your approval.
The OptiMax engine, when running properly, is reported to be a good engine with plenty of power.
According to the Mercury Service Manual for the Optimax 225-HP engine, the ECM performs the following functions:
-- Calculates the precise fuel and ignition timing requirements based on engine speed,
throttle position, manifold pressure and coolant temperature.
-- Controls fuel injectors for each cylinder, direct injectors for each cylinder and ignition
for each cylinder.
-- Controls all alarm horn and warning lamp functions.
-- Supplies tachometer signal to gauge.
-- Controls RPM limit function.
-- Monitors shift interrupt switch.
-- Records engine running information.
There is no mention of an exhaust gas sensor or a knock sensor. What this implies is that the ECM runs in "open-loop" mode. This means the engine is pre-programmed with a number of tables which determine the amount of fuel and ignition timing to be used based on input from the sensors (mentioned above), but that no mechanism of returning results of those settings (as would be provided from an exhaust gas sensor or a knock sensor) is employed.
The implication of an open-loop ECM is that the engine will run well if the pre-set fuel injection and ignition timing values are a good fit for your boat and its load. If your particular boat, motor, and propeller combination, in conjunction with the way you run your boat match up well with the stored values, you get good results. If your boat is particularly set up so that the engine loads are not in the anticipated regions, or if you run the engine at speeds where the designers did not anticipate you would operate the engine, then you may have problems.
Other notes: First generation lower units have been sources of criticism, too. 2002 was a major step forward for Optimax. Generally, before 2002, you need to start doing research and/or decide if you are comfortable with the engines' history.
