switching from a mefi3 to mefi4
 

Hello everyone
Just wanted to check if someone could help me out here
I repowered my ebbtide deck boat from a 5.0 to a 5.7 last winter
Also went from using a mefi 3 tbi fuel injection for mercruiser to a mutiport fuel injection mefi4 from marine power

The 5.0 was a 1999 with a mefi 3 computer mercruiser
the marine power is a 2000 with a mefi 4
The problem I'm having is going into reverse after being in forward.If I shut off the engine it works fine, but is very hard to get in reverse running.I never hooked up the shift switch on the shift plate when I made the change over.Come to find out this is what kills the engine quickly to let it shift.Problem is the harness I got with the marine power injection didnt have a place to plug the switch in.Does anyone know if one of the wires on a mefi4 marine power computer for a 5.7 is for the shift interrupt switch
Other than that the boat runs great, but it sure is hard to dock

Thanks in advance

Re: switching from a mefi3 to mefi4
 

I don't have a service manual for Marine Power engines, but I have on for Indmar engines which I believe are the same. It does not show a shift interrupt input to the ECM on a MEFI4 system.

I believe that your engine uses a Delco EST distributor. If that is the case you could use a normally closed interrupt switch wired to open the Ignition Control circuit (pin J2-31 at the ECM) when activated. That's how Mercruiser did it on some Alpha/EFI engines.

Dave