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Sebago02

Something running in or near engine

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My boat is on the trailer and as soon as I turn the battery switch on there is something running in the motor compartment. There are no accessories on and it is not the bulge or blower.  Never heard this before and can't locate were in the engine it is coming from. Key is not turned so it is something automatic and tied directly to the battery.

Anybody heard this?

Thanks!

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You did not provide what type boat, power plant, and what accessories you have, but every power plant utilized in our boats have several electric motor driven support pumps that are all relay actuated. My guess is that your fuel pump relay is stuck in the on position. Power tilt/trim pump has both an up and down relay, and on some systems there are actually two. Trim tab pump (hydraulic tabs) of a trim actuator motor (electro-mechanical) may be running if the switch has stuck, or their relay has failed. Best way to find is get your head down in the bilge space a listen carefully. Tell us where the noise is coming from and we may be able to help   W

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The boat is a 2002 196 SSI with a 5.0L Merc Alpha I/O. I do not think it is the trim/tilt as that sound is higher pitch and I can run the trim up or down with the other electric motor still running. The sound seems to be coming from the front, behind the serpentine belt.  Where is the fuel pump located?

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Someone might have removed the mechanical engine water circulating pump. Replaced it with a electric one. They are available for race car use.

The high pitched sound might eliminate a electric water pump.

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You did not mention if your ride is injected or Carbed, but I'll assume injected. There is a water cooled fuel supply module mounted inline after your fuel filter. Trace the lines from the filter assm. toward the fuel rail and you will find the module. It contains both a low pressure and high pressure fuel pump. Atop the engine, you will find a bank of plug-in relays, and you can look for the label that says fuel pump or you can simply unplug each one until the noise stops. Replacements are less than 20 beans retail, so I carry a spare as the same part number is used for all the relays. Some boats have two, and some as many as 6.  W

Module:

http://www.marinepartsplus.com/catalog/mercruiser/serial/5.0L_MPI_ALPHA-BRAVO/8M0049000/15322-55

Relays (items #14)

http://www.marinepartsplus.com/catalog/mercruiser/serial/5.0L_MPI_ALPHA-BRAVO/8M0049000/15322-40

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Thanks Wingnut - you know your stuff.  The issue was one of the relays. I have the old one out and in my hand so should be an easy replacement.

Enjoy boating!

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I would check the simple things first. Check to see if your float switch is stuck causing your pump to turn on. It should take to seconds to check. Than a  wash down pump and/or fresh water pump.  Than I would like at the fuel pump. You can use your hand and feel, to see if the pump is running too.

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16 hours ago, Sebago02 said:

Thanks Wingnut - you know your stuff.  The issue was one of the relays. I have the old one out and in my hand so should be an easy replacement.

Enjoy boating!

Add your model year, engine model, horsepower, and boat description to your cover page and we will be able to provide feedback in the future without prospecting for information. Enjoy your summer, and hopefully the fuel pumps survived the bad relay situation.  W

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