Finally got the Rx-7 running and now it’s having the same issue again of starting, idling for 1-3 seconds and dies.

If I ground the wire/pin 1k coming from the Ecu then the car is able to stay running but then I get the error code 51 for the fuel pump relay which puts me into a limp mode which will not allow me to rev over 20% load on the accelerator.

Here is a video of it starting, the egr and speedometer ecu codes are on but these do not impact starting the vehicle.

 

What if any modification are on the car? when was the last maintenance done particularly the fuel filter or any removal or modifications done to the harness.
-before removing or going to the extreme check the basics: TPS sensor out of range, battery health, ground connections, fuel pump voltage at crank and when car turns over( check for voltage dropping below spec)

 

You have an issue with the fuel pump speed relay. That's what the code is trying to tell you.

Short term you can jumper F/P and GND in the diagnostic box to run the fuel pump full time.

Read up on the fuel pump relay setup, everything is under the cruise control area by the igniter.

When you turn the key to On, it's priming the pump and you get pressure in the system. Once it starts the fuel pump relay isn't there or something is up with it so the voltage drops out to the pump and the car stalls once the lines drain out their fuel pressure.

Shouldn't be too hard to sort out.

Dale