I have a 350 MAG MPI serial number 0M350565 in a 2002 Crownline with a Bravo 3. Some background, the boat is mint and has rarely had any issues. Over the last two seasons it has only been in the water 10 times max. Needless to say, the fuel is/was old. This season we have been out over 10 times. Ran WOT. No issues.
Over the past weekend while coming up on plane I hear a pop or a bang. Very much like a back fire. Boat immediately dies. All vitals show to be good (temp, oil pressure, voltage). I immediately try to restart. It idles and is able to put around at a low rpm. Vitals are good. Dies again at this low RPM. We decide to stay close to the marina and enjoy some sun. Decided to re-try. Able to get on plane. Dies about 200-300 yards out. Immediately try to restart. No go. Wait about 3-5 minutes, try again. It is once again about to put around for a bit at a low rpm and dies. Pull the in-line fuel filter and notice a rattling. Shake it out over the water. Dark plastic comes out on the intake end of the filter, nothing comes out of the exit. Reinstall, same thing but acts slightly better. Decided to call it quits and got off the lake.
Later, upon further inspection it appears that part of the structure inside the filter deteriorated and came apart. This did not lead to any plastic past the in-line filter as mesh inside the filter was still intact.
This is what I have done so far to try and resolve the issue. Seems to have a slightly rough idle on the hose. Fuel pressure is 40 psi with ignition on. At idle the fuel pressure bounces between 35-41 psi rapidly. See video below. At 1000-1200 RPMs it bounces between 30-40 psi. All other engine vitals are good. Fuel pump(s) seem to make a different noise than usual when priming. They seem to make a fluctuating noise. Not sure which one is making the noise. At idle the right one (the cooled one) has a slight whine.
Idle Noise and Fuel Pressure - 350 MAG MPI
Over the past weekend while coming up on plane I hear a pop or a bang. Very much like a back fire. Boat immediately dies. All vitals show to be good (temp, oil pressure, voltage). I immediately try to restart. It idles and is able to put around at a low rpm. Vitals are good. Dies again at this low RPM. We decide to stay close to the marina and enjoy some sun. Decided to re-try. Able to get on plane. Dies about 200-300 yards out. Immediately try to restart. No go. Wait about 3-5 minutes, try again. It is once again about to put around for a bit at a low rpm and dies. Pull the in-line fuel filter and notice a rattling. Shake it out over the water. Dark plastic comes out on the intake end of the filter, nothing comes out of the exit. Reinstall, same thing but acts slightly better. Decided to call it quits and got off the lake.
Later, upon further inspection it appears that part of the structure inside the filter deteriorated and came apart. This did not lead to any plastic past the in-line filter as mesh inside the filter was still intact.
This is what I have done so far to try and resolve the issue. Seems to have a slightly rough idle on the hose. Fuel pressure is 40 psi with ignition on. At idle the fuel pressure bounces between 35-41 psi rapidly. See video below. At 1000-1200 RPMs it bounces between 30-40 psi. All other engine vitals are good. Fuel pump(s) seem to make a different noise than usual when priming. They seem to make a fluctuating noise. Not sure which one is making the noise. At idle the right one (the cooled one) has a slight whine.
- Remove the fuel sender and syphon 100% of the gas out of the tank. Replace it with fresh 91.
- Replace the in-line fuel filter.
- Replace the Water/Fuel Separator.
Idle Noise and Fuel Pressure - 350 MAG MPI
