Oil Pressure Switch not wired, Fuel pump runs constantly

[Wakeboarder141]

Let me preface this by saying I am a tire/suspension mechanic, but not an engine guy. I recently purchased a 1990 Bayliner Capri 1850 with a 4.3L Mercruiser carb motor that is not original. The previous mechanic wired what I believe is an automotive fuel pump that is not oil pressure controlled so it runs constantly when the key is in the ON position. It appears now that there is a purple wire that runs from the fuel pump to the ignition coil. I am hoping someone can help me figure out how this is supposed to be wired to the oil pressure switch. Is the oil pressure switch the chrome bulb near the coil, or is it located elsewhere? Thanks.

 

[Rick Stephens]

Not stock, since it has the added relay, which is the best way to do the pump power.

 

[Wakeboarder141]

Not stock, since it has the added relay, which is the best way to do the pump power.

Sorry, you lost me there. It already has that relay or I need to add it? Is the chrome part on top in my picture the oil pressure switch on this motor? This has all been rewired so I don't know if any of my wire colors correspond correctly.

 

[Bt Doctur]

The dome thing is the oil pressure sender for the gauge , you need this wired in Standard Motor Products PS-64 Oil Pressure Switch

 

[Wakeboarder141]

The dome thing is the oil pressure sender for the gauge , you need this wired in Standard Motor Products PS-64 Oil Pressure Switch

Where does that install, and how do I wire it? Thanks!

 

[Rick Stephens]

Sorry, you lost me there. It already has that relay or I need to add it? Is the chrome part on top in my picture the oil pressure switch on this motor? This has all been rewired so I don't know if any of my wire colors correspond correctly.

an oil pressure switch is Tee’d off the port that I next to the distributor. The power, which is the purple wire running to the electric choke, is attached to one lug of the oil pressure switch and the other lug gos to the fuel pump to provide power to the pump when more than 5 pounds of oil pressure is present.

Power also goes to the pump from the outside lug of the starter to provide pump power when cranking.

I like making those two sources engage a relay to power the pump since it takes the power going through the oil pressure switch down and greatly extends switch life.

 

[Scott Danforth]

or you can plumb the oil pressure switch into the port above the oil filter boss on the block.