Oil Pressure Switch advice needed

[MN86_4winns]

I'm converting from a mechanical fuel pump to electric on my 5.7l and need advice on installing an oil pressure switch. I have read many postings on this topic in this forum and this is my understanding:
The oil pressure switch will be teed with my oil pressure sending unit.

The oil pressure switch has 3 wire connections:
1: fuel pump positive feed
2: starter solenoid to provide 12v during starting
3: purple engine wire to provide 12v with oil pressure

Is my understanding correct?

I spent 2 hours look through the parts books at the local auto parts store looking for Oil Pressure Switches for this type of application and was unable to find one.

Online I only found 2 different Mercrusier Oil Pressure Switches, 87-864252A01 Oil Sensor Kit which only has 2 wire terminals and a audio warning switch with only 1 wire.
I also located a 3-wire Crusader Oil Pressure Switch Part Number: CRU98176 for $56 at http://bpi.ebasicpower.com/ Will this one work?

 

[Don S]

Re: Oil Pressure Switch advice needed

Go to NAPA and get a NO (normally open) oil pressure switch that closes at about 5 to 7 psi. 2 wire setup and hook it up like this.

 

[MN86_4winns]

Re: Oil Pressure Switch advice needed

Thanks Don

I did find a "Oil Pressure Switch - Universal Marine" on NAPA's website. Their switch has 3 wire terminals, I'm guessing that 1 of them may be a ground?
http://www.napaautomotive.com/Maste...ption=Oil+Pressure+Cut-Off+Switch+-+Universal

 

[tommays]

Re: Oil Pressure Switch advice needed

It will have a Common and a NO and NC connection

You will not need the NC


Tommays

 

[MN86_4winns]

Re: Oil Pressure Switch advice needed

Help... I think I did something wrong.... I got my new engine started for about 2 minutes and then the electrical system went down and killed the engine. I tested the slave solenoid and discovered it was bad.

For the 12v purple I connected to the positive terminal on the coil. The purple/yellow wire (12v feed during starting) I connected to the yellow/red wire at the starter that comes from the slave solenoid. I do have 3 terminals on the starter solenoid, the main terminal with the red and orange wires, the second terminal with the yellow/red wire from the slave solenoid and the third terminal has nothing connected to it. I checked the third terminal during cranking but I didn't get any voltage. I'm guessing that by back feeding 12v through the yellow/red wire killed my solenoid and probably also was running the starter solenoid. Should the third terminal on the starter solenoid kicking out 12v while cranking?

FYI: I'm running a 1986 Thunderbolt IV system that didn't have an oil pressure switch until now. I got a MERCURY OIL SENSOR KIT PART # 87-864252A01 that I found on eBay, the oil switch from Napa was out of stock and on factory back order.

 

[Reel Poor]

Re: Oil Pressure Switch advice needed

The purple/yellow wire connects to terminal D. Yes you should have power on term D while cranking.

 

[Don S]

Re: Oil Pressure Switch advice needed

When you had the purple/yellow wire attacted to the solenoid yellow/red wire, yes you will be feeding the solenoid and it should be causing the starter to stay engaged after you let the key off.
It MUST be hooked up like in the diagram, as the solenoid plate in the starter solenoid prevents the starter from being energized like the yellow red wire will.

 

[MN86_4winns]

Re: Oil Pressure Switch advice needed

Thanks guys, it all works great now... I also added an indicator light to the purple/yellow line.