have a 99 avs 33 w twin 502 mpi's. I'm an accountant so I could just use some direction. Port battery went out recently. Had to come in with son pushing parallel switch to get in last week picked up new battery and while running today voltage was 14 on starboard and 10+ only on port,

any ideas where to start rather than the shop?

Do you have the battery switches in both? If you have them in the first setting from off than that engine will only charge that battery. If you have a dead alternator on one engine that battery won't be charged.

two separate switches...... just off and on...... was thinking I just had ONE alternator but its just ONE power steering pump. probe alternator on Port side....

Ordered new alternator from DB electrical...... will see how it goes....

first thing you need to do before changing that Alt would be to check the alt output on the port engine. The problem may not be with the alt. It could be a wiring issue between the alt and the battery

and I do that how? I have a millimeter which output do I hook to on back of old alternator.

Why don't you just take it down to one of the parts stores. They will test it for free.

beat advice yet.... taking off in am

I tried getting mine tested at Advanced or Autozone, they couldn't figure out how to do it since it wasn't out of a car that they could click on, on their screen. I had to take it to an actual generator/alternator rebuild shop.

Hope your area stores are better than mine. Can't tell you how many times I've returned a faulty alternator and they tested it good, but yet it was bad.

Catch this, way back after dealing with one place that never found one bad, I decided to follow the person back to the test machine. He said you can't come back here, I said yes I can and I wanna see if you guys are hooking them up right. Ummm, they don't have a machine ! They got rid of it years ago, owner didn't want to spend the money to have it fixed nor replace it !

Working with parts stores on a daily basis, unfortunately I have about 2% trust in them. Sad !