Hello, very new to using forums period. Normally just searched through them.
I have a 93 civic dx (w/2000 dx single non vtec engine using same manifolds ecu sensors etc.)
Having an intermittent problem with the fuel pump not priming before cranking.
I am good with electricals, and have narrowed it down to the ecu not sending the ground signal to the main relay that powers fuel pump relay coil.

Also I am getting 12v to the yel/blk ecu input right @ the ecu from the main relay, when key is on.

Does this mean the ecu is bad?
sometimes it will just work out of the blue without touching wires or anything, after a period of about a minute or so goes by with switch on.
Sometimes it won't work at all. Sometimes it works fine Please!!! help lol.

 

*sorry when i say i'm using same manifolds ecu sensors, i mean i'm using the originals for the car 93. Original harness, injectors, ecu, distributor etc. all obd 1. blew the original motor and found a cheap single cam from a 2000. Probably not the worst swap you have heard of.

 

Are you saying that you have tested the ECU/ECMs FLR [fuel pump relay] output and there is no ground even though there is power on both the ECU/ECMs IPG1 and IPG2, [12V+ inputs from PGM-FI Main Relay]?

If so, I would also guess ECU/ECM is bad, although I would confirm the ECU/ECMs ground is good. 94

 

I Know this is years later, but i felt it was necessary to write that the indeed the ecu was the problem. Found another obd1 non vtec ecu and it ran great!