This is a white wire with a male connector that comes out of the harness right by the #3 cylinder?Click to view attachment

Cylinder head temp sensor.

I've got the temp sensor plugged in to another connector, a green wire that comes from the harness under the battery.

I think Andy is right, and if you don't have the CHT plugged into the correct wire off the harness your car won't start. It is supposed to connect to a single white wire off the harness near Cyl #3 as you describe it. Better check again.

Where do I plug in the wire from the oil pressure sensor?

Wiring diagram: http://www.pelicanparts.com/914/parts/Elec...lectric_73C.jpg

Oil pressure switch is #40 on the diagram, which connects to a green and (red?) wire. That is likely the wire to which you had the CHT connected.

As mentioned in previous thread: disconnected oil pressure switch won't keep the engine from starting. But a disconnected (or faulty) CHT will.

Is that a wire that has a male connector with a plastic cover over the end, which is under the battery?

No. Print out the wiring diagram. It's all there.

Here's the link to all the diagram info: http://www.pelicanparts.com/914/914_electrical_diagrams.htm

You need the two 1973 wiring diagrams and their corresponding legends. A PO may have hacked the wiring at some point, but use the diagrams to understand what it's supposed to look like.

OK, so the legend shows the pressure sender wire going to #90 - Regulator Plate
What is a regulator plate and does this diagram apply to my 1974 1.8?

I believe the regulator plate is more commonly known around here as the relay board. It's got the relays, fuses, and several multi-wire connectors on it on the driver's side of the engine bay. Yes, you do have one (or you better have one).

Edit: yes, this diagram applies to your 1974 1.8. If you're looking specifically at FI wiring connections, notice there's a separate wiring diagram for L-Jet and D-Jet on that page. But for the components you're looking at (oil pressure switch, CHT, etc.), that diagram applies.

So, I believe, the wire under the battery goes into the wiring harness which goes to the relay board.

The green wire which is in the same harness as the white one (and should have a female spade connector) goes to the oil pressure switch which sticks up out of the tin next to the distributor on the passenger side. The wire under the battery sounds like the oil temp sender connection to the console wiring harness... but if you post a pic we can confirm.

Thanks guys, switched the wire for the oil pressure sender and it fired up!
This is a great day after all the weeks of troubleshooting.
And, It happened on my Birthday!
I've included a picture of the wire under the batteryClick to view attachment

Good for you. I know you've been working on this for a couple of weeks, and that's always a winner when it finally fires up And Happy Birthday.

The green wire under the battery tray should have a black stripe on it.

If so, it goes to the oil TEMP sender.

Congrats, Ricardo! Enjoy these victories...and your birthday!

Nice work!