Just thought I'd ask as I'm completely stumped. I have a 1997 Albemarle with twin Volvo 5.8 FI motors (charcoal colored). They are inboards.
I've been having problems with my starboard side motor. First off, it's always had this issue where the tachometer, when running out our canal at around 1200RPMS, will fluctuate and jump around.
Now I have a problem. Last weekend the starboard motor died on me while out fishing. Worked great for the hour run out, started fine for the 3 moves, then went to start it to make a move for the 4th time and it wouldn't turn over.
Now it will start, hard, but it will only idle. If I attempt to put it in gear, or even touch the throttles, the motor dies like you flipped the key. It will usually idle for about 20-30 seconds before dying. The thing that baffles me is that it will die if I try to use the throttles at all, load or not.
Now, I flipped almost everything from the good motor to the bad. I changed (not in order): plenums, fuel rails/injectors/regulators, fuel pumps (both high and low pressure ones), fuel float bowl (I guess used to prevent vapor lock?), the computers. I also removed the fuel lines and ran them to a gas can to remove any boat problems (I.E.- pickup in the tank, etc).
After this entire switch, the good motor still runs good, and the bad motor doesn't run, even with the good motor parts.
The only thing I haven't changed is any of the sensors, throttle bodies/TPS sensor, and distributor.
I do have a scanner but it seems the boat is a 1997, but the computers are labeled and have the diagnostic connection for a pre-1995 setup (computers looked to be labeled 1994). Now, any idea of what the problem could be, or where I should look? I ruled out fuel/air, spark seems to be fine (since it idles then dies).
I don't know if the tach issue is related, or if there are specific safety sensors that might be bad (like a overheat sensor or some kind of tilt sensor?). Any opinions. Any and all help is greatly appreciated!