Not likely something is in the pump, the fuel water separator is before it. Could be a tired valve in it though resulting in lower volume.
One other thought, what about an airleak between the tank and pump. Had that problem with a crappy electric fuel selector switch.
How about the coil and wires? What do the plugs look like? All the same or is there just 1 bad cylinder.
BTW, Bought 1 of these last year. Great for diagnosing bad plugs/wires, low compression, etc.
http://www.actron.com/cgi-bin/web_st...=5794677_18028
Gary

thrillseeker - on your tank(s) are fuel shut off valves make sure both are all the way open. how many tanks do you have mine has 3 bow / mid / rear . all had 1/4 valve with 3/8 hose ends which made big restriction . just something easy to check

No we are swapping out the carbs tonight and running it tommorow will keep you posted. We all ready swapped the boxes disconnected the rev limiter, checked the fuel line and fuel pressure, we are at a loss still. Will keep you posted, hopefully one of us will find the trick soon.

Check your Distrbutor Cap!!!!!!
I had that problem twice a year in my old boat (1999) The contacts in the cap would get that whitish/greenish corrosion on the ends. I would always know when to change it because I would start losing WOT RPM's. I kept a spair, and would clean the other one for next time...I know it sounds to easy, but It was the last thing I did, and it was that all along!!!:) Good luck

THrillseeker I know this is dumb to ask but did you check your distributor cap? We have new caps.

krumbsnatcher, Yes I cleaned them. The following is a list of stuff that I have tried, although I think I found my problem. You may want to consider some of theese.

I switched the following parts from good motor to bad motor

carbs
coils
distributors
ignition modules
tachometers
ignition key switches
engine wire harnesses
plug wires

I also jumped 12v to coil+ post directly from the battery to eliminate the coil, played around with ignition timing, I removed all my fuel lines and blew them out, checked all fuel valves, changed water separating fuel filter, blew through the feed line to the tank, checked fuel pressure at the carb. I finally pulled the plugs out and found my problem described in my other thread.

Hope you have better luck than I did.

Wish I could say that was my problem, but I just put in all new plugs rotors,etc.

Keep me posted if the new plugs fixed it. By the way how did your plugs come loose? Are you running Aluminum heads?