I have a 30' Spectre and am rebuilding engines to NA 548CI which should be aourn 650 to 700hp with 1050 dominators. I was running stock mercury fuel pumps off the sea water pump which are not in the best shape. Has anyone ever had a problem with the cam going out in these?
The supply line to the tank has been change to #10 and the filter is mounted low in the boat.

Should I:
-Buy replacement mercury seawater fuel pumps which would probably be borderline in my application $130
- Buy above with Hardin Marine upgrade kit $130 +$159
- Go with the Mallory electric 140 GPH Marine - $259

If I were to do the Mallory does the regulator they come with allow for a bypass or is there another regulator/fitting or something else involved? Can the bypass be run back between the tank and the filter with a T fitting? I don't think I can get a return line back to the tank.

I have a 540 n/a that made 650 hp on the dyno and used a weldon 600 flow thru style pump. Weldon said it was good for 800 hp at 9 psi, in a carbed engine. Works great, quiet, draws very low amps.It was a little more expensive at $352 from Kinsler fuel injection, but weldon is one of the best.

I just rigged up my new 540 with Aeromotives by-pass regulator and pump. I have heard only good things about their system. I also have a mechanical Edelbrock pump bolted to the motor with the required check valve. That way I can cruise on the mechanical pump and click on the electric when I beat on it.

I have t/na540s and Carter 140 GPH internally regulated mechanical pumps (part# M61045). Flat out 5800 rpms and the pressure never moves (dash mounted guages)
Only thing I had to do was tap in small nipples into the vent holes for the overflow tubes

Check out CV Products. I have their billet mechanical pumps mounted on my sea pumps. There was a thread about them recently.

Lot easier to install than an electric. The electric will require a relay, pump, wiring, oil pressure cut off switch, bypass regulator with line back to the tank, etc.

Holley Black

Beat on it??? Wide open is just optimal cruise speed.

Take it easy there Dave, not everyone has 1300+ h.p.

I'm running a 540 N.A. EFI, and use an Aeromotive electric pump. It seems to work great. You'd obviously be running lower fuel pressure with your carbs, which wouldn't cause the pump to heat the fuel as much, but motors seem to like cooler fuel temps, especially on startup on those hot days.

I would recommend strongly against teeing your return line to the suction of the pump. Fluid systems are already inherently finnicky when it comes to priming and maintaining suction pressure. It would also rob you of the ability to use your fuel tank as a fuel cooler. I envision your return line draining back through the filter to the tank after shutdown, then next time you start the pump, you'll draw air and a vacuum from the return line through the pump to the rail, then voila, a totally airbound fuel system. Just my $.02

Got my vote.