Mercruiser EFI
03-31-2005, 11:10 AM
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Re: Mercruiser EFI
Originally Posted by pachangalpina
I guess it depends on which wiring harness you have. The 95 should have been a MEFI1 setup, to change to the MEFI3 I believe that you will have to alter or replace the harness.
thanks
03-31-2005, 11:37 AM
#12
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Re: Mercruiser EFI
trailblazer,
If you're building the engine back non-stock and not building it to someone's specs that HAS done it and programmed an ECM for (like a packge deal from Tyler Crockett, PM, ASM etc.) then seriously consider spending the few hundred buck more and going carb! You're going to have to send the ECM off to be reprogrammed and if it's totaly custom you're likely to go back and forth more than once to get it right, if you can get it right. It's not like you can run it on the water with a laptop hooked up building fuel MAP's.
I speak from experiance. Although a different motor (2000 7.4 MPI) I can show you a picture of 1 of 2 pieces left of a piston that you can only tell it's a piece of piston because you can see peices of ring embedded in the side, also the bend rod that ended up resting through a cylinder wall. I was hard headed and wanted to keep the MPI although there was major head work done as well as cam etc. which ended up needing bigger injectors etc. and shipping the ECM back and forth for months trying to get it tweaked right.
On the upside (if you can call it that $$$$$), I now have a new motor. It's carbed.
Now I have and MEFI-3 ECM, most of a harness, partial MPI sytem, 8 42 lb HP500 injectors all to sell. Oh, and a 7.4 short block needing 1 rod and piston and a little bondo for the 3"-4" hole ion the #1 cylider wall. 
If you're building the engine back non-stock and not building it to someone's specs that HAS done it and programmed an ECM for (like a packge deal from Tyler Crockett, PM, ASM etc.) then seriously consider spending the few hundred buck more and going carb! You're going to have to send the ECM off to be reprogrammed and if it's totaly custom you're likely to go back and forth more than once to get it right, if you can get it right. It's not like you can run it on the water with a laptop hooked up building fuel MAP's.
I speak from experiance. Although a different motor (2000 7.4 MPI) I can show you a picture of 1 of 2 pieces left of a piston that you can only tell it's a piece of piston because you can see peices of ring embedded in the side, also the bend rod that ended up resting through a cylinder wall. I was hard headed and wanted to keep the MPI although there was major head work done as well as cam etc. which ended up needing bigger injectors etc. and shipping the ECM back and forth for months trying to get it tweaked right.
On the upside (if you can call it that $$$$$), I now have a new motor. It's carbed.
Now I have and MEFI-3 ECM, most of a harness, partial MPI sytem, 8 42 lb HP500 injectors all to sell. Oh, and a 7.4 short block needing 1 rod and piston and a little bondo for the 3"-4" hole ion the #1 cylider wall.
