boatnuts

I have a new 2006 383 MPI Mercruiser engine that sat crated for 4+ years. I installed it in my boat last month and after what I thought was a reasonably thorough pre service, started and ran it. Aside from lots of problems with the power steering that necessitated the replacement of both the ram and the pump, the engine ran real nice. This past weekend while out for a short cruise it suddenly began running like it had water in the gas. I managed to limp home (5 miles) at 1400 RPM and pulled the filter. The gas was clean. Not really surprising because the tank is new and the high test fuel was fresh. I changed the filter and reprimed. Engine started but very rough. Starboard exhaust was noticeably different from port. Shut engine down and pulled the plugs. All appeared almost like new. Did a compression test before reinstalling the plugs and got 185 to 190 which is good. Now the engine wont start at all. It only has 5 hours on it. I am very old school in terms of engine knowledge and dealing with problems and this engine has a mess of electronic stuff that is over my head but I do have spark and there is fuel up where you would attach a pressure tester between the 2 fuel rails. No alarms sounded during any of this so I assume there will be no stored error codes. Does anyone have any suggestion what I have had go on here? The boat is in a remote area on an island aprox 7 miles from mainland. Generally speaking, the local service resources are very limited in expertise so I am hoping this is something I can solve and cure with your help. I am thinking that possibly the injectors are plugged. How hard are they to pull and clean? Any and all input will be greatly appreciated.

Westcoast

I would start with a fuel pressure test. Could be a bad fuel pressure reg.

brian valery

I have the same engine and when first installed had the same issue. You have gunk in the filter screens in the fuel system. Chances are your old engine was not EFI and may not have had an electric fuel pump. Each injector has a screen, the fueling cooling system has screens and the fuel pump has screens on both sides. It could be a clog at any of these screens or even all of these screens. Start with the fuel pump and move throught the fuel sysem checking each screen.
After all clean install a fuel/water separation filter and you should be good to go.
Good luck.

boatnuts

brian valery - thanks
I am going to get a pressure tester and work my way through the system this weekend. The fuel cooler looks it will be fun because of it's location.

boatnuts

Checked the rail pressure on Sat. morn and it was 38 PSI
Started with the pump at the separator and pulled, inspected, blew with air and reinstalled.
Pulled the cool fuel system.
Inspected and tested pump independantly and got 80 PSI
Inspected and tested regulator and it opens at 43 PSI
Made sure everything was clean and blown with air.
Reassembled and bench tested complete cool fuel system.
Got 43 PSI on the output end that connects with the tube that goes up to the rails.
Fuel regulator opens and system stay at 43 PSI.
Weather was bad so I will not be able to reinstall system untill next weekend.
Is it possible that some unseen tiny speck of something caused this pressure drop?
Why is there not another filter other than the fuel separator?
This motor had start and run for the first 5 hours with absolutely no problems or hiccups.