I am building an NMEA 2000 network on my boat and in the process of changing the instrument panel gauges the new possibilities are making me wonder about no gauges. What I mean is the NMEA 2000 protocol can put up my gauge info on my display....... if the engine computer is compatible??????
This is where the big question comes into play. Will the ECM of these 1997 502 MPI engines put out data for NMEA 2000??
If not what protocol are they on? Is there a converter for these to put out display data of the engine info?
I can not find info, so far, that addresses this direction I am thinking to go.
What do you all know about this?

Mercruiser does not talk directly to NEMA, it must use a Merc gateway to transfer data. That said, with a 1997 motor, and not knowing your serial number, I will guess you have a MEFI 3 ECM and I don't think it will talk to NEMA

So do I understand this right that the Merc gateway for this MEFI 3 will not pass onto NMEA?

I have some j1939 to nema adapters if the engine has j1939 output

What does an adapter like this cost?
I am researching the whole approach of new gauges vs display data. J1939 has been around for a very long time so maybe the Merc stuff is there? That is part of what I don't know, what their communication protocol is?

Livorsi told me they would cost $250 each, they charged my credit card $450 each, so I'm not real sure what they cost?

I like how you're like, "meh, whatever"
First world problems

LoL

Been digging into this issue for a couple years, (not an expert) but the only system which transmits data that can be read by NEMA is via smartcraft. The MEFI 3 does not do smartcraft, it needs to be up to a 555 ECM. Now there may be some analog to digital (A/D) converters, which can translate the data, but I don't know of any

Interesting. So for my triples I guess that is one needed per engine. That starts to make price competition back towards new gauges vs going to all display.
If the Merc stuff is J1939 the Garmin has this protocol built into the 7600 series along with the NMEA 2000. I could run J1939 to the display if that is what Merc is.
Thanks for the info. The jury is still out on this project.

Does the Merc MEFI 3 use J1939? The Garmin system can use this protocol too.