Port Engine Shuts Down: No Alarm or Obvious Issues Noted

John-Burgess

Member
Nov 26, 2009
58
Wakefield, RI
Boat Info
2008 330DA Sundancer (2009-2015)
2014 Regal 42 SC (2016-2018).
2010 370 Sundancer (2019-Present)
Engines
8.1L Bravo 3
My 2010 Sundancer 370 with 8.1L w/outdrives has developed a repeatable problem. Attempting to get onto plane with throttles at 3800 RPM and approaching 15 knots the port engine RPM's drop down to about 2600 RPM. Moving both throttles to WOT, RPMs start increasing then port engine shuts down. No alarms or codes in Vesselview. Engine immediately starts up and repeated same sequence 3 times before heading back to dock. Called Mercruiser support and they indicated that it is not unusual to have no alarms/codes in Vesselview for an engine shutdown as there are too many things which can cause a shutdown. Loss of RPMs down to 2600 could indicate going into guardian mode but I can increase RPMs back up a bit (~3000 RPM) before engine shuts down.

Temperature was steady and normal, oil pressure normal and flow rate normal. No issues with starboard engine and added 45 gallons of fuel to each tank same day so I don't think it is bad fuel. Also I did not feel any surging, etc when engine dropped RPMs nor when engine shut down. In a waiting queue for mechanic to check with Mercruiser computer for any signs of faults.

While I am waiting for a mechanic, any suggestions or thoughts on what this may be related to?

Thanks,
John
 
No codes or errors indicated usually points to a fuel issue.
A failing fuel pump, clogged regulator or injectors, maybe something along that line.
 
I really appreciate both of your replies. This makes sense given other parameters were normal. Mechanic will do a computer readout and then fuel pressure test next week. I went to boat this AM just to look around to see if I accidentally pulled out a wire or hose when I replaced the rear bilge pump between the engines on Saturday. Nothing out of place from what I could see but could not find the fuel pressure regulator. Not much room with twin 8.1's & Axiom set up to trace the fuel lines to the rear and not knowing exactly where the fuel pressure regulator is mounted.
 
Not sure about your year but on my 2001 mercs the fuel pressure regulator was mounted on the fuel pump/cooler. It only bumps up the pressure at higher rpm's and was vacuum controlled. Small 1/4 inch vacuum hose from under plenum down to the cooler/pump with a tiny diaphram on it.
 
Mechanic diagnosed the problem to be a bad fuel module. Service department indicated that the unit is on backorder from Mercruiser until next week. Boating season just got a couple of weeks shorter.
 

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