Live in Miami. On hot humid mornings turn on ignition and check engine light remains on for anything from 2 to 10 minutes. With check light on the fuel pump does not pressurize. Finally light will go out, pump pressurize and engine will start. Relay and fuel pump have been changed. Occasionally moving auto trans selecter seems to solve problem but not always.
On dry cool days light goes out in seconds.

Totally baffled. Anyone?

 

Clean and tighten the G101 ground wire connection on the thermostat housing. Also check whether fuse 31 or 24 is loose or corroded. If these do not help, swap in a known good ECU to see whether the problem is solved.

 

Thanks for your advice. Ground and fuses seem to be ok. Please advise which CIVIC models and years have the same ECU?

Does anyone have a suitable ECU?

 

I believe just for testing purposes you can use any model Civic OBD1 ECU (and pretty much any OBD1 Integra ECU also). I had a similar issue with my car, I put the key to the on position and fuel pump didn't prime. I swapped ECU's with the key still in the same position and as soon as the new ECU was plugged in I immediately got power to the fuel pump. Hope everything works out for you.