I have a 2003 wellcraft excalibur with the 496 ho mag. I have been having issues with ot running, barely runs and have taken into my local merc dealer. They say I have low fuel pressure and replaced the bboster pump saying due to the fact that it had no inline filter in front of it that it hurt thr pump. Still only getting 33psi at fuel rail and telling me the next thing to look at is the fuel regulator that is at the fuel cooler. This all makes sense but they are telling me they have to pull the motor to change out this little regulator. Does that make sense ? or anyone heard of this.
Thanks in advance for any help

On a 2003 496MagHO you should have what is called
Cool Fuel II system which is the secondary high pressure fuel pump, a fuel cooler with the fixed fuel pressure regulator on top of it and all located in a plastic covered flange mount over the top of the left side motor mount. If they take the plastic cover off, they can remove the fuel cooler assy. with regulator fairly easily and change the regulator and re-install without pulling the engine. They should also check the inlet filters on both primary (low pressure lift pump) do a water seperator filter change and check inlet screen on high pressure pump at the Cool Fuel. The fuel pressure should be 43-45 psi at the schraeder valve, key on engine not running. Hope this helps.

Best Regards,
Ray @ Raylar

Ray, thank you for your input...I will be stopping over to see the mechanic and take a look at the little room they say they have to change out that regulator. My boat had no inline filter to the booster pump so it supposidly ruined the pump which was replaced. The next stop they say is that regulator by the cooler. They say they have about 4 inches between the stringer and the cover of the cooler to get in there, but I am going to see for myself in the morning, I just cant belive you would have to pull the motor to get to it. Thanks again for your input...this forum is great along with people like you that help us out.

Is your mechanic a 200 lbs+ heavy set , J/K . It's a tight place down there with the motormount in place , but doable without the engine removed, especially on a single engine application. I'm going to take my fuel cooler/pump out today because the opposite happening to me. Pressure is 70+ at the Schrader valve causing rich fuel at mid and idle conditions.My Rinda scan tool verifies this.
The first thing started on my engine was the IAC pintle stuck ,causing rough idle and stalling. Replaced the IAC valve and fixed that , but now the pressure regulator is acting up .My engines [ 6.2 MPI ] have only 190 hrs , so I'm not happy about that since the warranty has expired years ago.Fortunately this happening to my port engine with little more room to work on , compared to the starboard engine I'd have to remove the bench seat to lay flat on the floor to get to the Cool fuel assembly.

As you can see it looks pretty tight , but I had managed to take the system out in less than 1/2 hour before.

Took the pressure regulator off the cooler unit and found the stainless filter partially clogged up. After cleaning it and reverse blown with compressed air , the fuel pressure returned to 43 pounds.Now I'm expecting the starboard engine acting the same way , but before that happens I'll look it that filter as well. The s/s screen in the high pressure fuel pump inlet was clean . I use the Merc fuel filter before the low pressure pumps , so I wonder were the contamination is coming from. Always have fresh fuel and the gas tank was sqeaky clean upon inspection when I installed a new fuel sending unit recently.The s/s screen is quite small [ around 1/4" so assume it doesn't take long to get fouled ,even at relatively low hours. I guess this item should be included in a yearly maintenance just like the seawater impeller that could last 20 or 200 hours. I could have been out boating today instead of slumbering in the bilge , lol.