Loss of engine power; Mercruiser 5.0l MPI/Bravo 3

[Phillbo]

Thanks for the follow up. So many find the issue and just stop posting (until another issue arises).

Glad you got it straightened out and enjoy the boat ! The SE model is my favorite of all the pocket cruisers.

[Jduncan99217]

I had a similar thing happen to my 7.4ltr Merc. It turned out to be leaking exhaust manifold gaskets.

[mmwjr]

Originally Posted by Jduncan99217

I had a similar thing happen to my 7.4ltr Merc. It turned out to be leaking exhaust manifold gaskets.

Not sure I understand how a leaking exhaust manifold gasket would cause a loss of power.

[Elshu]

Originally Posted by iceman

Just want to close out this thread with the final resolution. The reader's digest version is: the Crank Position Sensor was bad (intermittent), leading to incorrect timing and thus loss of power. The mechanic's theory is that the sensor was damaged 2 years ago during an engine overheat incident, but didn't fully fail until this year. I've posted more details on other forums, so if someone's interested I can repost here.

As always, thanks for your help and advice!

Tom

Would it not advance past 3000rpm under load? Also did you experience a large shake?

[iceman]

Originally Posted by Elshu

Would it not advance past 3000rpm under load? Also did you experience a large shake?

That's correct, the engine RPM would not go past 3000 regardless of how much throttle I applied. I do not remember any shaking.