2005 Suzuki DF115 - Spark Plug Fouling

I bought a pair of 2005 DF115 4-stroke motors new in early 2006. The motors now have 440 hours and ran perfect until about three years ago. I got some water in my tank and it only affected the port motor. I removed all gas/water from the tank and installed a quality RACOR filter with a see-thru bowl on the bottom. I also run Heat and fuel injector cleaner to alleviate fuel issues. The tank is always kept full and I installed a new O-ring on my gas cap. From my tank, the a single fuel line runs thru a filter, thru a Faria fuel meter, thru the RACOR (one input, two outputs), then to the motor.

My issue:
The plugs constantly foul in the port motor. I've changed plugs several times, each time with new Bosch or NGK. It does not matter. I also changed both fuel filters (high and low pressure) - no affect. The only thing that helps is if I take the entire fuel system apart and purge all gas. I use an air compressor to blow out all lines, fuel filters, fuel injectors, and fuel injector rail. It is a short term fix as I do this each time I run the boat (120-250 miles). Lately at cruising RPM after 100 or so miles, the boat will start missing for a second or two and then pick back up. If I pump the throttle a couple times, it will be good for a few miles, then start missing again. It almost seems as if the system is fuel starved for a second or two. It idles perfectly at home. I can let is run at about 2800 RPMs in the driveway with no issues. BTW, I also just rebuilt the fuel injectors to no avail.

Again, I have no issues with the starboard motor and it is fed from the same RACOR? The plugs are clean and the motor runs perfectly.

Does this motor have an sensors that could be telling the motor to run rich?

Thanks for your help and time
Chad

Re: 2005 Suzuki DF115 - Spark Plug Fouling

These motors have a very simple EFI system that only adjusts the fuel tables based on a couple of sensors, Engine temperature sensor being one of them. There are also air temperature, air pressure, and exhaust temperature sensors which could effect fueling. Another though is a weak low pressure fuel pump which could need a rebuild and not supplying enough fuel to the high pressure pump chamber. Also, All the plugs fouling or just a pair?