fuel pump/ fuel system question for a new build
 

Hey guys, so Im new to the world of building a more high performance boat, here is a little history I have a 1996 Baja 252 with a (not original to the boat 502 Mag MPI) and I am looking to do some upgrades. The boat is in great shape but the engine is just down on power and it has been consuming some oil so I figure it is time to freshen it up over the winter. The boat was born with a 454 MPI in it, not sure if t was a Magnum or not but it still has what I believe to be original MEFI2 computer now adapted to the 502 Mag. After speaking to someone on this topic I could be running out of fuel on the top end causing it to just stop pulling after 4K RPM and nose over.

Regardless of the current situation this is my plan:

• bore the stock 502 out to a 509Cid
• Rods/pistons for a 10.0:1 comp
• aluminum heads ( open cooling put fresh water only)
• Not sure of cam profile yet but would like to get slightly aggressive
• 525 EFI intake
• Eddie marine thunder manifolds with dry tip risers
• Holley HP stand alone EFI system
• Sieman Deka injector

To get back on point with this topic, what type fuel pumps are the more high performance boats running? I am very up to date with the fuel injection world in cars but I do not know if it also adapts to the world of boats.

Option A

• Good quality inline fuel pump (400LPH)
• Good quality fuel pressure reg with 1 to1 boost reference incase I ever all a blower
• Feed the pump with a -10 AN line from the tank and to a Y-block then from the Y-block -8 to each fuel rail.
• Out of each rail with a -8 to the regulator
• -8 line from the reg back to the tank for a good return system

Option B

• Good quality inline fuel pump (400LPH)
• Good quality fuel pressure reg with 1 to1 boost reference incase I ever all a blower
• -10 from the tank to pump
• -8 from pump to first rail
• -6 to loop to 2nd rail
• -6 out of the 2nd rail and to the reg
• -6 back to the tank

Am I trending in the right direction here? My goal is 600 Crank HP

Your stock fuel system isnt keeping it from revving over 4000 currently unless your regulator or pump are bad. For 600 hp, your plan B is plenty, Smitty

Making 600 through that intake will be a challenge, gonna need good heads, custom cam, correct injectors and a very good tunner..... and IMO more cubes.....but it can be done I had a set of 540's with that intake and they made 630

From what I was told the 525 Intake is good for a well setup 509 but wont move the CFM required for a 540. If I don't hit the 600 mark and get even in the 550 range it will be far above what i have now. I'm not looking to chase a specific number but I want it to run right and run strong for what it is.

What about fuel separator, is there a better unit than the stock or just repurpose it?

I run the Teague units its -10 from the tank to the rail but mines a bit different than your build, the stock one with the inverted flair fittings can get choked down

ive taken those stock separators, drilled out the inlets/outlets bigger, drilled the threads out to 37/64, re tapped them to 3/8 npt, ran 3/8 th npt to an in and out and made 785 hp with them blown with no fuel pressure drop fwiw

using a standard mercruiser filter?