Arrrgh...turns out the isolator was not the problem. Boat still will not start if the isolator is wired correctly. The only way I can get the boat to start is if I put the #1 battery connection directly on the isolator post coming from the alternator. I know that's strange but the engine will start then. When starting though the engine turns slowly but does start. I must be back feeding the power somehow when I wire around the isolator. I traced all kinds of wires last night to no avail. The generator also will not start. I show 12.7 volts at the generator starter (easier to get the leads on) but as soon as you click the start circuit it drops way off.
I do have wiring schematics printed out and intend to trace every inch on Saturday morning. If I don't find the problem it looks as if I will go through the process of pulling the boat and towing it to the dealer. That kills at least several days along with enough fuel through my truck to wear the stripe off my credit card.

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2008 Vista 278 Volvo Penta 8.1 Gi 375 hp
1999 Horizon 220 5.7 GSi