2012 Mercruiser 3.0MPI hard starting

[DCMacGuy]

Yesterday was my second time having my boat out - the first being the on-water test which the marina had already put the boat in the water. 2012 3.0MPI, 325 hours, fully serviced. Based on my past experiences with MPI MerCruisers (350 Horizon, 496Mag), I expected it to fire right up - it did not.

It took 3 rounds of 10 seconds or so cranking, both at idle and with the throttle advanced before it caught and stumbled to life. It idled fine after that, and the rest of the day fired right up (it seems to require more cranking than I would expect in general though). Aside from that, it runs like an absolute top.

I realize that most on here have probably not worked with a 3.0MPI, and they are not exactly common - but any thoughts on areas I might check to see why this is behaving this way? I've seen 3.0TKS models that start easier than this one does.

 

[alldodge]

Its always best to have the motor scanned for codes.

Do you hear the fuel pump run for a few seconds when the key is turned to ON, before cranking?
When cranking does the tach show around 300 rpm?

If all the questions are yes, then need to check fuel pressure at the rail. Even though you were told it was serviced, some things may not have been done. Would remove the fuel filter and dump contents into a clear container or baggie to see what's there

 

[DCMacGuy]

I do hear the pump prime (I made it a point on the second go-round... I may have eagerly jumped past that on the first key cycle - you know how it is when you have a new toy ).

I'll watch the tach next time. It does crank noticeably slower when it is cold than when warm, but I figured that was due to the viscosity of the marine oil.

I'll take a look at the fuel pressure and filter contents. The boat is a former rental (with surprisingly not a single scratch on the exterior), and I have all of the service records from the marina. I'll do some digging this afternoon... my copy of service manual 46 is en route.

Thanks for the fast reply!

 

[alldodge]

When the tach stars showing rpm's this tells you that the ECM is getting the firing signal. If the tach doesn't move, then the injectors will not fire.

 

[DCMacGuy]

Well, looks like I may have things figured out. Yesterday at the ramp (complete with a date in tow), I heard the power trim pump slowing down a bit dropping the trim. It would barely turn over and started throwing SmartCraft Low Voltage warnings at my phone (I have a VVM Module installed). After jumping the boat off with my truck, which fired right up and cranked faster than I have ever heard - I had a lovely day on the Potomac. Last night, I discovered that the "New" battery the marina installed in my boat is a 645CCA battery and is most certainly not new.

I'll be buying a new battery this week. My intent is to eventually run dual batteries - if I do that, do they have to be matched size or can I use this battery as a secondary?

I'm hoping a new ~800CCA battery solves this issue.

There are a whole boatload (no pun intended) of other issues I am dealing with which I am considering taking to Brunswick marine and the Maryland Attorney Generals office (falsified hours and some lies covering it up being one of them) since I bought it from an authorized Sea Ray dealer.

 

[alldodge]

Bats don't need to be the same size, they just need to be the same type as in lead acid, or AGM or Gel. Can mix a lead acid starting with a deep cycle

 

[DCMacGuy]

Perfect! Thank you for the quick reply!