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Joe, Marine Mechanic
Category: Boat
Satisfied Customers: 7251
Experience:  ASE, electronics, Marine mechanical and electronics, pwc, wiring, all around repair tech,
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330 Sea Ray Sundancer 1998 with twin V-drive 350/300Mag FI

Customer Question

330 Sea Ray Sundancer 1998 with twin V-drive 350/300Mag FI with Velvet drives ORIGINAL 1200 HOURS.
This started off with an initial repair plan of doing a valve grind on the Port engine because I had already had the Starboard engine done by another mechanic. During reassembly 'Bubba' broke 2 injectors while attempting to install a valve cover while the exhaust manifold was on. These were replaced and once in the water and after 1/2 of run time I discovered that the oil was water contaminated and the FWC reservoir had long disappeared.
This lead to engine removal for full rebuild at a certified engine rebuild of whom assembled the engine at their plant with the heads and intake manifold as per my request when I delivered it and picked it up.
As the story evolves it became obvious that I had to be hands on so, I did assemble all of the attachments to the motor such as full FWC, all pumps, belts and fuel pump prior to the lift for the reinstall to the boat.
The motor was lifted in and installed to the velvet drive. 'Bubba' dropped in the distributor. It didn't start right up. 'Bubba' played with the timing and then gave up saying that it would run but requires a Merc computer diagnosis. It had a feeling like a dead miss so we also checked the leads from the cap, and unhooked individual, respective leads to the injectors to see if there was difference.
The engine was hunting by as much as 200 RPM at a 1800 RPM trouble shoot. I launched it and I ran it to the base camp and could see that it had the power and all the max RPM required of 4800 and some, but was rough and then would stall at idle.
I gave 'Bubba' his walking papers at the fix it yard after discovering that the extra hose clamps for raw water pick up, the clamps for dip stick and oil change stick and lower protection plate at bottom of bell housing were not installed.....and some other stuff.
So now here we are. The Starboard engine had a full top end rebuild by another man. Started right up when finished and runs very well so I can use it for a reference for switching components back and forth.
I have switched the IAC units and no change to this motor. I have switched the ECU and no change. I have fuel pressure gauges installed on the fuel rail on both motors and they stay identical at 22 PSI...(and increase slightly when you rev the motors up). There are vacuum gauges on both motors teed into the throttle body base. They seam to float between 18 & 20. The fuel filter is clean.
I have not replaced the distributor cap but ensured it was mostly corrosion free at contacts inside the cap when the cap was installed.
These motors are visually immaculate clean and all the wiring contacts had previously been ensured for function. Plugs are all less than 5 hours.
I wouldn't know if this could be part of trouble shooting analysis but the starboard tach jumps all over the place intermittently...thinking it is a sealed unit and probably through away.
Submitted: 2 years ago.
Category: Boat
Expert:  Joe replied 2 years ago.
Thank you for allowing me to assist you, my name is ***** ***** I will be happy to assist you with your concern today.
Wow, I am sorry to hear of these troubles, I can say that unfortunately there are bad mechanics out there and based on all the problems I have 1 suggestion which is to have a professional look over the entire job as I am sure more things will be found. I honestly can say that based on what was missed there could be more serious problems. I would start by checking over the entire install and that everything is tight, if this guy installed the motor this includes the trans, everything inspected, then check distributor was dropped in at tdc, next confirm/set the timing, inspect the distributor cap and rotor, inspect injectors. Unfortunately it's pretty much like starting from scratch, think of it like reinstalling the motor, so that everything is checked and double checked. It'd be a good idea to also pull a compression check as well.
Thank you!
- Joe
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