Okay I have a civic 91 SI im able to start the car when i By pass the main relay but when I install a Brand new main relay I get the same problem NO power to ECU,fuel doesnt prime or my indicator wont turn on

Any ideas on what can cause this I can still use the car but when the wires arent secure well and they fall out the car dies
I have also checked my fuse and my connections behind both fuse boxes.

 

Hey I recently had that problem on my Ef. I bought the car with a bypass to the back of my dash fuse box. The yellow wire with black line with a gray dot was pinned into one of the power supply's in the fuse box

 

Have you checked for the 3 powers to the PGM-FI Main Relay, unplug the relay and test for 3 powers...

1- 12V constant, hot at all times.
2- 12V switched, hot in run and start.
3- 12V switched, only hot when cranking to start.

Also check the ground, [black lead] should have full continuity to chassis ground, [grounded at thermostat housing].

If all good, check for power at the injectors, [lead that is the same color at all 4 injectors] also check for power at IGP1 and 2 to the ECU. [will also be the same color as injector power lead. 94

 

I have the same problem plz let me know if u figure it out cuz im running out of ideas.