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dkarolak

Sea pump pressure low circuit

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I had a engine alarm go off and I had my local dealer put a laptop on it to diagnose. Twin 4.3MPI, Alpha 1, 2005. The code stated sea pump pressure low circuit (260psi I believe the tech wrote, can't read his handwriting). I had impellers replaced prior to last season and put less than 40 hrs on the boat. I put maybe 3 hrs on the boat this year. Any idea what or why this fault occurred? Appreciate any advice.

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Replace the sea water pump pressure sensor. MerCruiser part # 8M6000623 is the new style block psi sensor. Found on your power steering cooler, which is mounted at the back of the engine by the distributor. Will need a 1" wrench, or even better, a 1" deep socket. (1" deep socket for a 3/8" ratchet works best due to accessibility issues)

The original style (most had a white body, the new style is all black) had a tendency to allow water to reach the internal wiring, etc. which in turn shorts out the sensor. The ECM is then shown 0.0 PSI of water pressure, instead of say 2.0 to 10.0 PSI or so. ECM tells the audio alarm to sound that something is wrong, and places the engine into Guardian mode.

An easy DIY fix, if you can get at the cooler.

NOTE: on that model of boat, I don't envy you the task due to clearance issues. Twin 5.0L engines are worse though.

Block PSI sensor threads into item #5 in the link below.

http://www.marinepartsplus.com/catalog/mercruiser/serial/4.3L_MPI_ALPHA-BRAVO/884716001/11705-200

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Shepherd, just to follow up, I had the sea water pump sensors replaced on both engines and the error code went away. I will take her for a cruise soon to ensure that was the permanent fix (I'm sure it was). While it was in for service I had one engine IAC go bad so I had both replaced as well. I'm hoping she's a new women with all the repairs. Thanks again for your expertise.

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A water test is the only true way of knowing. Hopefully she's not a Prima Dona, but pure grace and beauty.

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