My friend and I have been working on a v6 4.3 Gi Volvo Penta Princecraft for a good month now. The people who own the boat got water in the fuel system somehow and it basically wiped out the whole engine. We have changed the map sensor, TPI, IAC, Ignition module, rotor, and fuel pressure regulator and still this boat will not run correctly. We now have basically narrowed it down to possibly either the intake manifold, or the ECU has been fried. SO, I have come here for possible answers before we blow up a boat! There are symptoms such as, VERY hard to start sometimes with backfire up through the throttle body, but when it does start it runs fairly well. Randomly will cut in and out when throttling the boat. If any answers could be reached on the subject I would greatly appreciate it.