Two prong oil pressure sensor

[Baker7888]

I pulled the diagrams for the LT1, will work out something for you, easy to follow.

This way all you have to do is just start car with the key.

The diode below has the amps rating you need and are just spade connectors. I haven't used this particular one before, so I ordered a couple and will test.

That’s awesome! Keep me posted

 

[Baker7888]

It does kinda work like safety switch from how I've looked at it over the years. One blade obviously trips the light at low pressure, the other blade powers the choke with a fused lead in the fuse box. Since it closes when pressure hits that oh-no level for the light it should do the same for the fuel pumps safety stop by, my uneducated guess, grounding out that circuit. Might even be able to repurpose that choke circuit by running a lead from the choke's plug to the pump/relay & use it's fuse.

Pagrunt you are saying one blade powers the choke. In factory form, if there is a low oil pressure scenario, is it trying to kill the motor via choking the carb ??

 

[pagrunt]

Pagrunt you are saying one blade powers the choke. In factory form, if there is a low oil pressure scenario, is it trying to kill the motor via choking the carb ??

Yes, one is for the choke but I don't think it'll choke out the carb. I've ran my original 229 out of oil on the highway & it never stalled out the motor. It's most likely just a tie in to power the circuit & give it a warning light. I've never seen the choke ever trip the light.

 

[ELCAM]

That terminal switches the power to the electric choke heater, the choke heater does not turn on till there is oil pressure.

My assumption is that folks were turning on the key but not starting the engine allowing the choke to start opening when the engine was still cold, causing cold start problems.

 

[Baker7888]

I actually went to the standard site to get concept of operation and factory specs, their site is b**bs on a bullfrog use full.

78 diagram shows as grounding which is NC, normally closed, yet it appears as one spade is NC and the other is NO, normally open. If that is the case, that is easy to wire. It just has to be wired correctly or your dash light will be always on or it will never work.

PS226 is the TBI one I'm familiar with. Closes the FP circuit and opens when no oil pressure, I.e.: engine is shut off.

On yours you want switch closed with oil pressure to run the FP, E-Choke, Excite for Alternator.

Then the reverse..., switch closed, grounds "oil" light when no oil pressure. So essentially a flip flop switch.

Very easy to wire I just want to make sure telling you correctly

I found one piece of it and I guess the 126T is ceramic disk that operates it. I was always under the impression the one you showed was simple SPST Spring operated but I guess not.

I'm just going to buy one and hook up to air to verify operation. Once I verify operation, wiring it is the easy part.

I'm doing a TBI to carb conversion so I need to get one any how, don't like to use the old junk.

78Delta88 let me ask you this.

The Holley 3 prong switch I have is labelled on each prong. I think what I'd like to do is use this switch because I already have it, and follow Holley's diagram to wire it to the FP (pretty straight forward)

What I would like to do is use the Holley 3 prong switch in place of my existing 78 malibu 2 prong switch, meaning follow Holley's diagram to wire fuel pump but also take the existing two prong wiring and just tie it to the Holley switch. The problem is the 2 prong switch isnt labelled so I was hoping you could help. If I know which side is NO and which is NC then I am home free.

On a side note, the factory 2 prong plug fits the switch either way so how does that work?

EDIT I just realized you mentioned during testing that the OE switch isnt labelled and couldnt tell apart. Oh well...Well if anyone has any info let me know. Basically want to cut these 3 wires and tie to the appropriate prongs on the holley switch.

 

[78Delta88]

78Delta88 let me ask you this.

The Holley 3 prong switch I have is labelled on each prong. I think what I'd like to do is use this switch because I already have it, and follow Holley's diagram to wire it to the FP (pretty straight forward)

What I would like to do is use the Holley 3 prong switch in place of my existing 78 malibu 2 prong switch, meaning follow Holley's diagram to wire fuel pump but also take the existing two prong wiring and just tie it to the Holley switch. The problem is the 2 prong switch isnt labelled so I was hoping you could help. If I know which side is NO and which is NC then I am home free.

On a side note, the factory 2 prong plug fits the switch either way so how does that work?

EDIT I just realized you mentioned during testing that the OE switch isnt labelled and couldnt tell apart. Oh well...Well if anyone has any info let me know. Basically want to cut these 3 wires and tie to the appropriate prongs on the holley switch.

With the key on probe those two openings one should light the test light. The other one will need to feed 12v to the pump

 

[Baker7888]

With the key on probe those two openings one should light the test light. The other one will need to feed 12v to the pump

Will do. Should be able to drop a battery in it soon

 

[78Delta88]

Will do. Should be able to drop a battery in it soon

Cool beans brother. ;-)

 

[78Delta88]

I know you kept working on this. Did you get it all figured out? I ordered some stuff almost 2 months ago, the last of it came at end of past week.

Below is example of wire loom. I ended up using the feed from the lamp test to prime pump prior to start and then once the engine starts the pump is transferred to oil pressure switch.

 

[Baker7888]

I know you kept working on this. Did you get it all figured out? I ordered some stuff almost 2 months ago, the last of it came at end of past week.

Below is example of wire loom. I ended up using the feed from the lamp test to prime pump prior to start and then once the engine starts the pump is transferred to oil pressure switch. View attachment 206224

Thanks for the response. No i have not messed with it since i last posted. My thought was to get battery in it (real close) and use test light to try to figure out factory wiring, then hopefully incorporate that into my holley 3 prong switch and ditch the factory sensor. This will free up a hole on my wye for my mechanical oil pressure gauge (might switch to electric) However I have not gotten this far yet, still tinkering with other fitment issues, longtubes, clutch, crossmember etc…

The picture above. Looks like you have two relays. What did you come up with exactly?