2005 Enzo beeper sounds then engine dies

[Deez 0]

Need some help fellas. I have a 2005 Enzo sv230. Has the mercruiser 5.7.  It had a miss under load at the end of the season last year so this spring I changed spark plugs, wires, distributed cap, and rotor button.  First time I put it in the lake it carnaked and idled fine. Idled for about 2 minutes waiting on my friend to park the truck. After picking him up from the dock it randomly died. Now every time I crank it it runs for a second and alarm sounds and it will die at low rpm. If increase rpm to around 2,000 or more alarm sounds and it acts like a rev limiter cutting fuel. This happens through the whole rpm range. It did clear up for a moment on the lake just long enough to get it on plane and see that the miss under load was now gone but this new problem has me scratching my head.  Engine temp was ~130, oil pressure was 40. 

[Packrat 13]

Might try looking at this thread it solved my beeping problem on 2008 Enzo 5.7 Black Scorpion

 

Edited May 24, 2019 by Packrat
Edit

[Deez 0]

Ok what I have so far. Took the boat to a local guy that was the “mercruiser guy” at local dealer for years. He put it on computer and the engine showed no codes. We checked fuel pressure and it was 23-24#s he said that was too low. We changed inline filter and spin on fuel filter and checked again, same~23#s. Changed fitting coming out of fuel tank with check valve and no change. He figured try all the cheap easy stuff before we jump to pumps. Finally he ordered me the fuel pump and fuel cooler kit along with new pressure regulator. Put it on and still no change. With throttle in idle it cranks and dies almost immediately. If you leave the key on after it dies the pump continues to run to get the rail pressure back up. Seems like it shouldn’t have to do that and the pumps can’t keep up. Could it be the boost pump? Any ideAs?