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  1. #1

    Default Oil Pressure switch Diagram

    anyone have a wiring diagram for the 3 prong oil pressure switch and how to properly wire the elsectric fuel pump to it? thanks.

  2. #2
    Vice Admiral Reel Poor's Avatar
    Join Date
    Jan 2005
    The Sunny Beach of Gulfport, Ms

    Default Re: Oil Pressure switch Diagram

    This is a Mercruiser 2 wire switch.

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  3. #3

    Default Re: Oil Pressure switch Diagram

    see the thing is the guy had it wired to a toggle so you could hold the toggle, prime the pump and fire it up if it sat for a while. well i dont even think the starter solenoid terminal has a wire to the switch on it, and when it died in the water all of a sudden, the two wires i took off the switch when touched energized the pump even with the key totally off. so i think i will wire it as you have it and if there is still a problem, then replace the switch, also there are 3 terminals on my switch but i should only need 2 of them correct? which ones go to which wires?

    heres how i gather this to go, i need a wire from the starter solenoid to go to the pump, then i need a wire from the actual ignition switch(where the key is) to go to the oil pressure switch and then from the switch to the pump? so the fuel pump should have 3 wires to it then on 2 terminals. one ground, and 2 power sources? i hope thats correct. thanks for the quick reply.

    btw its a 1990 omc king cobra 4.3L, idk if thats the same as the merc or not. thanks

    because the actual problem was it was running fine and then died. would restart after i held the toggle to give it gas, then restarted and ran that gas out, the fuel pump was not getting power while engine was running, so that tells me the switch could be bad or bad wiring.

  4. #4
    Join Date
    May 2003

    Default Re: Oil Pressure switch Diagram

    For Mercruiser color codes, the YEL/RED starter wire connects to the normally closed switch contact, the PUR ignition wire connects to the normally open switch contact, and the common terminal goes to the fuel pump.

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