When I start the car it run's fine until I put my foot on the brake or any electric think comes on ,fans for the motor, lights etc. then the tach jumps all over the place then the car will die and is hard to get started again

My husband has a 1990 Honda Civic LX and he has the EXACT problem that you are experiencing. We have not got it fixed yet but we have been told by a mehanic that it can be battery connectors an wires to the battery, starter or that it will need a good tune up amonst a few other things. I will let you know what is wrong with our's when we get it fixed

Tachometer Test. Disconnect tachometer wire (if equipped). A shorted tachometer can prevent the vehicle from starting. The blue wire going to the Ignition Control Module (igniter) should be unfastened. Try starting the car again. If it starts, the problem is with the tachometer.

If that doesn't solve the problem, then I would replace the Ignition Control Module. Here's how:

https://www.askmehelpdesk.com/cars-t...tml#post265896