Port engine lost power after new alternator

[bjt0307]

1998 Well craft Martinique 3000 with twin 5.7 EFI Merc's. I had an issue where my boat would not start a few months back. Since then I had the fuel pump and alternator replaced. It started right up at the dock every time after. Last weekend I took the boat up the river for the first time since getting repairs done and after 30 minutes the engine with new fuel filter and alternator started to lose power. It finally stalled and alarm went off. When I tried to crank over I noticed the crank was not very strong. I came back to dock with 1 engine. Once I got to dock I turned key to engine that failed and nothing. No click nothing. After plugging back into shore power for 30 minutes I was able to crank engine again but it didn't start. Back when the marina replaced the fuel filter they noticed the alternator was not working on one of the engines so I had them replace it. I never had this issue before where the battery would die when cruising up the river. I would also think the alternator from other engine would be charging while running. I just put another $1500 into the boat with these repairs and now I seem to have a new set of issues. Any ideas and do you think it could be as simple as marina installed a bad alternator?

[goodday]

Sounds about the right amount of run time under power that not getting any charge,

[goodday]

Sounds like same issue, before, 30 min up river and mtr would quite, can u pull batt. ,see if it's taking charge off reg. Batt. Charger, , not over heating and tieing up, then starting when cooled dn.,oil pres. Good? Sea water pump working, my last impeller lasted a yr, chunks blocking water on mtr. frt left thermostat housing

[bjt0307]

I found it was the water pump on engine. I think I'm in real trouble now because marina replaced water pump now engine won't turn over. When traveling up the river I did not notice engine over heating. An alarm did go off and I immediately shut the engine down. Marina is putting in a starter as it won't crank to run a pressure test. I really doubt it is the starter as it turned over every time when working. I have a Merc 5.7 EFI. Marina said Im looking at 6-7k to replace engine if it overheated. Im already 2k into a fuel pump, alternator, and water pump. Plus last year I spent 4k on bellows, trim cable, and gimble bearing.

[goodday]

How is sea water pump,? Bottom right of engine in frt of starter, that cools power steer, fuel cooler, then enters thermostat frt port side housing, ck for being clogged, engine must turn over by hand or they wouldnt need to replace starter, shut dn at alarm u are ok on engine,

[bjt0307]

The sea water pump had a drip which marina thinks over time rusted out the alternator. They think this may have affected the fuel pump as well. After alternator and fuel pump was replaced engine turned over no problem. I was told the sea water pump parts were by the bilge do it sounds like it fell apart. As soon as alarm went off I shut engine off. What's odd is I did try to start again a few minutes after I shut engine off. It had an odd crank. 29 minutes later I tried to turn engine over and got nothing. Got yo dock plugged in shore power and after 30 min had crank again but engine wouldn't turn over. I think I looked st temp gauge and didn't see it overheated. Plus I would think alarm would have sounded sooner before any damage. I really hope it's not the engine! Marina should be calling this morning with update. My other concern is does marina no what their doing. I'm going from one problem to another.

[goodday]

What ended up happening to that mtr issue?