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I'm getting an engine alarm that I can't figure out. Anybody wanna play?
2007 Rinker 370, Mercruiser 496 with Bravo 3 and Digital Throttle & Shift (DTS)
Both engines start and run normally. After a few minutes at cruise speed, the starboard engine suddenly decreases power and sounds a constant-tone alarm. If I throttle back to neutral for a few seconds, the alarm stops. If I go above 1000 RPM, the alarm comes back on. But if I wait 30-60 seconds, everything goes back to normal operation. I can nail the throttles and the boat jumps right up on plane as if nothing happened.
It happens at random intervals, and at any cruise speed above 3200 RPM. Sometimes, I can run for 30-40 minutes with no alarm. Sometimes, it happens within a minute or two.
My mechanic hooked up his code reader and found no error codes. The only error message in the SmartCraft engine monitor is a message saying the pitot tube is not working, but that should not affect the engine.
I have ruled out the following:
* It's not overheating. The water temperatures are normal and steady.
* It's not a faulty neutral indicator switch. I swapped the switches port-to-stbd and it did not change anything.
* It's not worn spark plugs. I just replaced them.
It has to be some sort of intermittent sensor fault, but I'm stumped. Suggestions?