Its doubtful in my opinion that you have a corroded harness to the engine. Can you be a little more specific regarding your ignition system, are you using a later model Rx7 80 - 85 electronic ignition or are you using the original twin point ignition. The wiring to the ignition is very simple in these cars and easily repaired without replacing the harness.
If you're running an original twin point iginition.
- are the ballast resistors wired correctly above the coils ?
- is the dwell angle set correctly for leading and trailing ignition ?
- are the condensers OK ?
- are the points OK ?
- If you car has been sitting for many years change the fuel filter, they absorb water with time and dont flow fuel very well.
- Check the fuel pressure from your fuel pump.
- are the ignition leads in good shape. If you have cheapies throw them oput, they are useless on a rotary engine and will cause you grief in the future.
You can bypass the entire ignition wiring harness by "hot wiring" the car. From memory you run a lead directly from +ve terminal of the battery to the +ve of the leading coil. Its been many years since Ive done it, so check a wiring diagram to ensure Ive told you the correct side of the ignition coil ! If you hot wire the car you will need to disconnect the "hot wire" manually to stop the running engine.
Like I said, you dont need to replace your harness. The hot wire will quickly determine if you have a wiring issue without replacing anything. Good luck
...here is a link to a Rx2 manual so you can determine whether to connect the "hot wire" to the +ve or -ve side of the coils. http://foxed.ca/foxed/index.php?page=rx7manual#rx2
and how about some new photos