I have a bone stock 1992 EG hatch b15b7 automatic. Sometimes the main relay does not prime the fuel pump (typically after sitting for more than a few days or when it's very hot out) but if I leave the key on after about 30-60 seconds the fuel pump will prime and the car will start and operate normally until the next time this happens. I have put a brand new OEM Honda main relay and tried other known good relays and it still occurs with any of them the same. It does not seem to be affected by neutral safety switch which is working normally. BTW car only has 120k miles. Is this intermittent ECU failure maybe to send the signal to main relay?

 

Sounds more like an ecu issue. Is the MIL cycling normally when the pump is not priming?

 

Nosir, it stays solid until the prime event just like as if the relay wasn't responding but I have 2 known good relays and a brand new honda they all work fine in other cars without delay.

 

Try another ECU. Sounds like an ECU cap issue to me.

 

I’d bet my lunch money it’s time for OP to get to solderin’


https://honda-tech.com/forums/engine...-them-3279850/

 

Hey man, having same exact problem, did you find ever fix it with the ECU replacement? Because I'm leaning towards replacing my ECU as well.