I didn't know you were spending all this time and money without having the correct manual. You may want to rethink this, The correct manual and a scantool would have probably saved a lot of both.
This is the manual we used in Crusader MEFI class.
I have been to MerCruiser, Volvo and Crusader MEFI classes. This is by far the worst manual. If I remember right this one has my notes on half the pages, soo many things wrong that I asked the instructor why it was so bad. His answer was it's the GM manual and has very little changes for Marine. Crusader/Pleasurecraft didn't have the money to redo it like Volvo and MerCruiser did. He said "this is why you come to class, so you learn how the system works and you will be able to know when the manual is wrong"!
Even with a manual, here is a cut and paste from the manual
@dingbat posted.
GM Powertrain Division service manuals are intended for the use by professional, qualified technicians. Attempting repairs or service without the appropriate training, tools and equipment could cause injury to you or others and damage to boat that may cause it not to operate safely and properly.
Something as simple as a compression test can be done wrong and lead to new issues.
Ignition Modules are sensitive to the amount of secondary voltage required to complete the spark plug circuits.
With the spark plug wires removed from any available ground, the module will be driven at maximum dwell saturation time for the coil(s) – read as HEAT. And when that maximum secondary spark is released, it may seek a ground right back through the ignition module – causing instant electronic failure.
When an engine is running with a spark plug wire “hanging”, you can bet the module and coil have had their service life compromised. How much depends on how long the wire was “hanging”.
To properly disable the ignition system on fuel Injected engines, with the key in the OFF position, unplug the crankshaft position sensor, remove the ignition relay or unplug the J-1 and J-2 connectors from the ECM before cranking the engine.
That said, the info on how MEFI works is useful.
I will warn you about using this manual to troubleshoot. While most of the components are the same, the software in the ECM is very different between the engine manufactures and also engine years. This can lead to replacement of good parts, and when that happens. The chance of getting the wrong/bad part increase and now you have 2 problems. This may explain why your symptoms have been changing. It's highly possible you swapped out a good part with a not so good part. I'm hoping you saved all the stuff you have replaced (especially the fuel injectors) they may be needed.
Because of the differences between software packages between models and years it becomes very important to know what software your engine has installed. The serial number can help so so much.
A few of the questions.
Does this engine use B+ to help control injector pulse width?
What strategy does this engine use to determine closed and throttle %?
What strategy does this engine use for engine protection?
Remember, the ECM’s decisions are only as good as the input information. If bad information is input to the ECM, then the ECM will make bad decisions. Bad decisions cause running problems.
Unwanted resistance due to corrosion is the hardest to find because the extra resistance usually doesn’t set any fault codes. The extra resistance does cause the circuit to flow less current which causes a voltage drop to or from a sensor, or it reduces current flow to an output (load device) which may cause the output to malfunction. Unwanted resistance due to corrosion usually will not set a DTC because the circuit still functions, just not properly.
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