mikem79

I had my '79 zx out on the shop pad warming up to check for leaks. Seemed fine then it just stopped running. I tried to restart with no success. since then I have tried a different fuel pump, both pumps did not run when the key was in the on position unless I disconnected the oil pressure sending unit plug. I even jumpered the connector and the engine tried to start then quit when I released the key back to on. Checked the dip stick and oil filler cap and all the connections that I could see, all looked good. The relays are clicking with the key to start so I guess they are working but don't know for sure. So, in short the engine won't start.

NismoPick

Welcome to ZDriver!

An engine needs three things to start:
-Fuel
-Spark
-Compression

To clarify what you've stated... the engine WILL start if you disconnect the oil pressure sensor? Sounds like it's the oil pressure sensor, or ignition switch.

Have you downloaded the FSM? XenonS130 - S130 Reference