I have a 454 330hp with mechanical fuel pump and a edelbrock carb with electric choke. The problem I'm having is that when the boat sits for a while (between uses-about a week or so) I have to pump the throttle about 25 times and crank it quiet a bit to get it to start. Once it fires it has no problem running and no problems starting the rest of the day. Almost seems like I'm totally losing fuel pressure and takes that long to get fuel back to the carb. Anyone experience this problem or have suggestions on a fix?

sounds like its losing prime. check the anti psyphon valve in the pickup in the tank. if not it may be the valve in the pump.

This is a common problem with BBC Carb Motors ....When starting the motor after the extended time ....Turn the motor over without setting the choke for a few seconds .....then set the choke and it should fire right away .......m

I'm not sure that pumping the throttle is doing anything at all. Have you looked down the carb while pumping it? Is there any fuel being pumped? Sounds like any fuel in the carb is either leaking out, evaporating or being allowed to drain back into the tank. The anti siphon valve is my first guess as well. Do all boats have them? I'm not sure. Wouldn't take long for fuel in the bowl to leak or evaporate. I think a shut off valve could be installed near the carb to prevent back flow into the tank.

it's normal...gas just evaporating over a period of time, with mech pumps, spin it over a dozen times, then pump 3-4 and you should be ready to go....Rob

Thanks for the advice! Let me know if this changes anyones opinion on the problem. The only thing I changed when I went from a holley to the edelbrock was the fuel line between the fuel pump and filter(#8124), added the edelbrock filter(#8130), and chrome single feed fuel line on the carb(#8134). I had to get a reducing fitting to match the end of the braided line and the fuel pump outlet. The old holley would fire after 3-4 pumps from a cold. Just wouldn't maintain an idle or keep running without pumping the throttle until the motor was warm. The edelbrock has been great. Just hate to see all the cranking on the batteries and starter to get it fired for the first time. You know what they say, "everytime it starts, is one less time it'll start in the future."