Two prong oil pressure sensor

[Baker7888]

Their diagram will work, their switch is marked, yet it seems to show that pump is energized by cranking, then control passes to the oil pressure switch after engine starts. It shows that priming of the system is done during cranking, which might be a problem, but maybe not. Won't know until it's tried.

It then shows power going to the coil and then the distributor. The coil works on the ground side and this is true for solid state or a points system. If your HEI is going to be connecting through its current GM method path, It should work just fine. No wiring to the distributor needs changed in that event.

Pics below is simple hook up, although it just the hard wire setup, when in reality it needs a fuse and should have a power relay. For simplicity sake, pics below. The manual switch primes and then once the engine starts you shut off the switch. Once the engine is running, 12vdc power to the pump goes through the oil pressure switch (OPS). The light is just in the circuit as an example of load, in reality the fuel pump would be replacing where the lamp is.

The extra white wire coming out of the switch can be omitted if not needed. The brown wire would be connected to the OPS, but I ran out of connectors. Electrically the way it is wired it's the same.

The priming switch by passes the OPS until the engine is running, then after engine starts it is shut off, 12vdc moves through the OPS to keep FP running.

Let me ask you this. Instead of using a toggle switch, what if I ran that wire to Start, would this work? In other words, key in Start position would prime the system and then run when on.

 

[ELCAM]

If you have the starter solenoid with the 2nd small terminal I would use it, it will do the same thing you want and would be easy.

 

[78Delta88]

If you have the starter solenoid with the 2nd small terminal I would use it, it will do the same thing you want and would be easy.
View attachment 202959

On the start solenoid you have the two small connectors ... One should be marked "I" and the other marked "S", like you show above. The best would be to just run your wire to the pump to the one you are using for start "S". As soon as the engine starts and you release the key, that line goes dead, and voltage to the pump goes through the pressure safety switch.

That would work and essentially how Holley diagrams it.

You will just have to try.

If you start getting hard start problems due to no fuel, then look at making a switch to prime.

 

[78Delta88]

If you are following the TBI to Carb project. The switch panel below is the one I'll be using.

The protected switch will be used to prime then, start button will be pressed.

 

[Baker7888]

If you have the starter solenoid with the 2nd small terminal I would use it, it will do the same thing you want and would be easy.
View attachment 202959

If you are following the TBI to Carb project. The switch panel below is the one I'll be using.

The protected switch will be used to prime then, start button will be pressed.

Thanks guys. I am using a 96 F body LT1 starter. See attached. I would like to avoid switches if I can.
Just to clarify, is this what you are suggesting? (See modified diagram)

 

[Baker7888]

....

78Delta88 Idk if you saw my last edit. Let me know what you think of your diagram that I modified in post #25

 

[78Delta88]

Thanks guys. I am using a 96 F body LT1 starter. See attached. I would like to avoid switches if I can.

Yes agree with you. With out using the ECU you lose the timer circuit on the FP, but it was designed to pressurize the rail. With a carb and well running engine you probably won't even need it. Just don't know until you try.

In reality on the pre-FI cars the manual pump didn't start pumping fuel until it started cranking, so it might be a non-issue.

 

[Baker7888]

Yes agree with you. With out using the ECU you lose the timer circuit on the FP, but it was designed to pressurize the rail. With a carb and we'll running engine you probably won't even need it. Just don know until you try.

In reality on the pre-FI cars the pump didn't start pumping fuel until it started cranking, so it might be a non-issue.

Ok thanks. Right now I am still a little ways out from cranking the motor but getting closer every weekend. Rear end of car kind of snowballed but it is taking shape nicely and I am close.....

 

[ELCAM]

Since the later model starter does not have the ignition terminal on it you will need to be creative to make the crank wire work. if you hook the purple crank wire to the fuel pump wire on the 2 port oil pressure switch the starter would engage as soon as the oil pressure came up.

To prevent this you could use a diode but it would need to be a big one.

Using a relay you could just use a common cheap diode.

 

[78Delta88]

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.