Sounds like the mefi fuel and timing tables could use some attention .......as for AZS ?????

We did a procharger kit on a 97 35 fountain back in 98. They used a fmu and areomotive 1000 fuel pumps. I forget but I think it was around 50 psi at idle and 80-90 at wot. That was there way to fatten it up. There was no tune on the computer back then.

Spoke to procharger they told me fuel pressure should be 35 psi at idle , which I now set up !

But the computer was tuned and Ocean Performance installed it. They may have come up with something different.

spoke to original owner of boat in long Island and He told Me also fuel pressure was never at 70 or 75 psi, he said around 35 psi! I guess the old owner may have played around with it !

90 at wot? Can stock injectors even handle that?

You may want to put an O2 sensor in your exhaust and do some careful spark plug reading since you are not real sure of the tune or if you do have stock injectors.

My motor was a 1997 502 mag with an M3 Procharger running 7 lbs. of boost at 5000 rpms. Stock injectors and stock tune. Base fuel pressure was 43 psi. wide open throttle fuel pressure was about 63 psi. This was with the Procharger supplied "FMU" fuel pressure regulator. Boat still went lean at wide open throttle 13.1 AFR.

How many pounds of boost are you running at wide open throttle?

Hi and thanks for the advice , I have temp sensors I exhaust risers to monitor the temp , I am currently rebuilding the engine at this time and I will see you when I install it runs with the fuel pressure that this 35 PSI ,

Good luck with the rebuild.

I would start from scratch. send the injectors to BUP to get them flow tested. then figure out who is gonna set this ECM up to run this setup correctly. it sounds like you can't get the real story from the previous owners-mechs of this boat. if it WAS set up to run 70 psi and you drop it to 35, you have a serious lean cond which will roast your new engine real quick. you hold an injector in your hand, you cant tell what it actually flows at what pressure. and as Hadley Lamarr said, O2 sensors...