I have a 28' Active Thunder with twin 350 Mag MPI. Starboard motor is using about 30% more fuel than port. All gauges read OK (and equal) except fuel pressure is a bit higher on the right side. Transom soots up on that side only, as well. I already changed the water temp sensor. Any ideas?

remove fuel pressure regulator and clean dirt that is on regulator filter

Is temp holding properly?
I have had blocked open thermostats twice this year!
Replaced one, next one did the same.
Both times I had sooty transom due to the computer running in cold temp conditions--thus more fuel!

The sensor you replaced, was it for the gauge or the computer? My 502 I have 2, one for guage and one for computer. Left sensor on my housing is for the gauge, sensor on the right is for the computer--it has the factory clip in plug
Did/do you have the proper sealant on the sensor? Needs to seal, but yet get the ground as well.
Siera sensors do not come with the sealant on it, and you cannot just use anything

I replaced the one on the right - for the computer. It already had sealant on it. Replaced the t-stat already and the temp is right on
. I think I'll check the fuel pressure reg.

find fuel pressure regulator,,if theirs a vacuume line attached remove the line and install a vinyl clear line..monitor the line and have a person start the engine and look to see if gas is being sucked up into the intake,,the diaphram rupture and the vacuume sucke the fuel out og the regulator...if your regulator is under the upper half of the intake then the diaphram is most like rupruted..i see it alot on 5.7 vortec's engines in trucks..