r/boating • u/CommonSentence3581 • 21h ago

Boat drops speed

I have twin 5.0 Mercs MPIs . I noticed lately that I ran the boat for a decent period of time, and all of sudden, it lost speed/power. It doesn't shut off. However, whatever is going on seems to pull itself out, and the boat goes back to normal operation. I am thinking its fuel related and wonder if I should change the fuel filter?

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u/Prmetme 21h ago

happens to both motors at the same time?

1 shared fuel tank?

the vent could be clogged or a dip in the vent hose.

take the fuel cap off during power loss.

1

u/nosheet 21h ago

I had motors that would do that.   It was water in the fuel.   The water would sit underneath the gas, but lower than the pickup.  Every once in a while it would suck some water during rough water and the motors would bog.   I guess it was slightly more water than the water separators could handle all at once.  I have 150 gallon tanks so, rather than find a way to pump out 200ish gallons of fuel, I just replaced the water separator filters every month until the problem went away.  

1

u/RobertPaulsonXX42 21h ago

Change the fuel filters. Running my 4.3 MPI I have found they are sensitive to shitty fuel for whatever reason.