Where is my oil Pressure Sensor?

[gtochris]

I'm positive when I started the boat in the spring my oil pressure gauge was working (on the trailer), first time I launched it, I had trouble starting the engine (never like that). Once things finally started, I realized my oil pressure gauge was not working. None the less, engine runs great! I'm convinced my oil pump is working right and boat runs same as always.

Fast forward, I've spent a month looking for the right sensor, no one seems to have the sensor I have. I finally got a sensor that I'm told is the newer version and I just need to splice in.

I've been super busy, boat has sadly sat in the slip for 3 weeks and I went down tonight to change the sensor over. First thing I did was start it up and disconnect the two wires that go into this sensor to see if perhaps I have corrosion. Doing this caused the engine to shut off within a minute. I stopped what I'm doing because perhaps this $50 sensor isn't the part I need?

The local marina doesn't have much of a good diagram, I pulled my gauge cluster and checked connections on the gauge and they are good and tight. Do I even have the correct sensor?

Thanks,
-Chris

 

[Bt Doctur]

an oil pressure sensor or oil pressure sender. most only have 1 wire to the sender for the oil pressure gauge

 

[gtochris]

I took two really good photo's of what I'm working with and what part I purchased however the forum is not allowing me to upload since they are too large. Below is the best representation of what I'm looking at if this can help anyone figure out my problem.

 

[Scott Danforth]

You disconnected the oil pressure switch which also controls the fuel pump

Gauge sender has single light blue wire

 

[gtochris]

an oil pressure sensor or oil pressure sender. most only have 1 wire to the sender for the oil pressure gauge

So perhaps the Sender (to the gauge) is the larger diameter part in the picture I posted?

 

[gtochris]

You disconnected the oil pressure switch which also controls the fuel pump

Gauge sender has single light blue wire

None of my wires in that area are blue.
The two wires I disconnected that you say are for my fuel pump are purple in color, the other solo wire going to the bulb part in the picture I posted is green.

 

[Fun Times]

Sounds like you found the the oil switch for the fuel pump safety system.... Then there is a oil switch for the oil alarm Tan/Blue wire normally..... Also there is a sender for the gauge that would be a light blue wire for the gauges...The gauge sender should look like more this, https://www.ebay.com/itm/Mercury-Qu...Pressure-Sender-Assembly-37293T-/191721126417

They could be either down by the oil filter area or up behind the rear port side of intake manifold area sort of by the distributor assembly.

 

[gtochris]

Sounds like you found the the oil switch for the fuel pump safety system.... Then there is a oil switch for the oil alarm Tan/Blue wire normally..... Also there is a sender for the gauge that would be a light blue wire for the gauges...The gauge sender should look like more this, https://www.ebay.com/itm/Mercury-Qu...Pressure-Sender-Assembly-37293T-/191721126417

They could be either down by the oil filter area or up behind the rear port side of intake manifold area sort of by the distributor assembly.

Thanks, I'll give a look next time I'm down by the boat for that!

 

[Bt Doctur]

your $50 merc switch a standard auto part PS 64 pressure switch $18
That switxh is not meant to take excess current when the electric fuel pump draws more current .lose the switch and lose the fuel . Best to wire in a 30A cube relay to handle the load

 

[harringtondav]

My 4.3 Gen 2 has the oil pressure switches located just above the oil pan below the ign. coil on the left/port side. The two wire switch controls the elec. fuel pump and the alarm. The gage pressure switch has one wire. Slight risk, but I jumped the alarm/fuel pump harness so my fuel pump would start at 'key on'. This improved starting greatly. Before I had to crank until oil pressure was detected before the fuel pump activated. I keep my eyes on my dash gages, so the risk is low, as well as the risk of loosing oil pressure in a well maintained engine that uses no oil.

 

[Bt Doctur]

Then your not even wired correctly to begin with . The outermost small lug on the starters solenoid is supposed to go to the fuel pump wire

 

[gtochris]

Sounds like you found the the oil switch for the fuel pump safety system.... Then there is a oil switch for the oil alarm Tan/Blue wire normally..... Also there is a sender for the gauge that would be a light blue wire for the gauges...The gauge sender should look like more this, https://www.ebay.com/itm/Mercury-Qu...Pressure-Sender-Assembly-37293T-/191721126417

They could be either down by the oil filter area or up behind the rear port side of intake manifold area sort of by the distributor assembly.

I poked around yesterday and found something that looked like it on the top of the engine near the intake on the port side of the engine (top down) insertion. it was the only wire that had blue on it but it also had some orange.
Could this be it?

My engine came without a VIN# or the plastic cover over the carb filter so I'm lost as to what the VIN range is for this engine as it appears Merc moved around some of the components over the years.