OK - Got a 1999 33 Donzi ZXw/ twin 502 Mags - One motor ran great then all of a sudden lost power. I scan it and pull Code 81 - "A" bank Injector voltage high. Here's the odd thing - Scan the other motor and it's a MEFI 3. Take a good look at the other one and notice the EFI Harness from the ECM is plugged into another harness similiar to "piggybacking". Odd. The motor with the problems has only 34 hrs on the scanner - obviously it's been replaced. (MEFI 4) (Other - MEFI 3-has 130hrs)

Is it common to replace an MEFI 3 with a MEFI 4 and adapt w/ cables? I haven't run across many boats w/ECM issues other than the norm - IAC, TPS, etc... no actual ECM failures.

And if you have any experience w/ this code - any scenarios explaining the code?

Thanks for any input!!

Thank God for Carbs.

The MEFI3 ECM's are no longer available. When they fail, the only option is to replace them with a "kit" than includes a MEFI4 ECM and wire harness adapters.

The problem is that the Mercruiser service manuals don't cover any of the additional trouble codes (like a code 81)of the MEFI4 ECM. The trouble shooting procedure below is from a Volvo service manual (unlike Mercruiser, Volvo did use the MEFI4 ECM on some of there late model engines).

Dave

Thanks - I did some more digging this morning with the help of a good friend @ a Merc dealer. History shows this engine has had two ECM's replaced, a harness replaced, multiple repairs concerning the knock sensor open/grounde etc....

This should be a fun one to figure out .......

Yo Dave - I've received a fax with the DTC 81 codes - but need to verify which cylinders are "A" bank and which ones are "B" bank -

Any ideas?

Thanks again for your help!

I believe "A" bank would be 1,4,6,7 and "B" would be 2,3,5,8

Dave