Having an issue with my boat coming on plane and some have suggested in may be in 'guardian' mode. Therefore, I am trying to locate a decent ecm scanner. Any ideas where to buy one?

Buy it from the manufacture http://www.rinda.com/marine/marine.htm
Picked mine up from them

There is no "guardian mode" on a 2000 502mpi.

Yes no guardian mode for engine, it does have power reduction mode; happened to my 502 MPI, would not go above 2400 rpm or so. Took it to a dealer because I wanted other things checked (that was a mistake). They thru plugs, cap, rotor and wires and gave it back to me. Said it was the knock sensor retarding the timing

Just an FYI for your note file

MEFI 1 93-95 year models - the largest MEFI ECM in dimensions HAD POWER REDUCTION MODE


MEFI 1 96 - 98 year models - medium size dimensions - NO power reduction mode

MEFI 2 98 year model GM ECM model number 16210729 - used for the 1998 350 mag and the L29 7.4 MPI - had .NO power reduction mode

MEFI 3 1999 till ECM 555 and PCM 555 came about 2001 had NO power reduction mode

ECM 555 and PCM all have reduction mode for a lot of stuff ranging from 5 % to 100 %.

PCM 09 many many reduction modes

back in that time frame if your app had the 55 or the 90 amp block fuse mounted at the starter the bolt and or nut going thru the fuse could have become loose or even very corroded, this will cause running problems and or loss of rpm. even it was overtighen by whomever the same problem can arise. Over tightening it can damage the block fuse or stripped out. FYI

http://www.boatfix.com/merc/bullet/99/99_03.PDF

another FYI for your files

http://www.boatfix.com/merc/bullet/99/99_08.PDF

And here is why everyone with OEM apps and or close to it should post your engine serial numbers. These numbers can pin point problem areas and save everyone a bunch of time and money. Anytime a boat comes in I basically can care less the year of the hull but the engine serial number tells me a lot form an OEM stand point. All OEM marine info, related service bulletins, service manuals and parts go off engine serial number PERIOD. I have been preaching this for a couple years up here.

With that said, I am not saying this is your exact problem but if your app falls under these serial number listed runs in the OEM SB posted above, I would be all over checking it out to make sure the correct newer version fuel pump was installed at some point in time. This is one the first things professional marine shops do is run the engine serial thru the OEM to find problems and part related issues pertaining the boat and or engine and or outdrive problems.. Just saying.

I know the boat and previous owner. Up till a couple weeks ago (new owner purchased), this boat ran flawlessly and is easily the nicest, most well kept 2000 27' Fever in the country (maybe world!).

I'd be very surprised if anything serious is going on.

If you need some help, let me know.