Ski partner has a 2004 SN 196 with Excalibur 5.7L engine. Symptoms:
-It is randomly bogging shortly after getting to speed, though it always seems to recover and go for the pass.
-At times it won't start. When this happens it is getting zero fuel pressure but disconnecting the high pressure supply line just a bit and reconnecting will result in resumed pressure and it will run fine after. Both fuel pumps are always running though this.
I took a pressure gauge to the pond and ran some tests.
-First key on and got only 20psi at the fuel rail.
-Second key on and got it up to about 30 psi.
-Releved pressure at the gauge to try again, turned key to on, and it only went to 5 psi. After that it wouldn't pressurize the fuel rail at all.
-I was about to say that the pump must be bad dispite that I could hear it run. Decided to try and disconnect that high pressure line from the pump housing and reconnect. Did that, gas started to spray into the rag, I retightened, and turned the key to on. Sure enough, the fuel rail pressure gauge shoots to 51 psi. Boat started fine after that and ran great with pressures holding nicely.
-Disconnecting vacuum from the fuel regulator brings pressure up just like it should.
-Holding vacuum at the regulator, it does not leak down.
So I'm trying to figure out what is going on here. It seems that even when the fuel rail has no pressure, there is pressure in the line between the pump and the regulator. Is it possible for the regulator to completely block fuel from getting to the rail down stream or is this some strange fuel pump problem? Let me know if I didn't explain something well and thank you all for actually reading this and any thoughts.
EDIT: Forgot to mention that we were having problems a month ago where it would stall half way through the course. Found out the low pressure pump was failing to supply enough fuel to the fuel control cell so that was replaced. I replaced the fuel filter in the control cell at that same time (this boat only has that one).