Does anyone ever encountered this problem:
I turn the key on, the engine cranks but the fuel pump won't prime, and I have a constant CEL.

It's a 1999 civic sedan. I have a chipped p28 with AEM uego wired to the conversion harness, and the gauge won't get power (won't turn on), and I can't datalog with HTS, just like when you plug the datalogging port but won't turn the key.

The thing is that I was testing another p28 ecu with a fried q31 transistor, and right after that I got the problem described above.

I tried my ecu and another chipped p28 and it won't change anything. I have tried replacing the main relay, and all other relays, I have checked all fuses, and still got nothing.

I don't know if it's a coincidence or not, but it looks like it's not an ecu related problem.

 

Check all grounds...

Transmission Ground
Valve Cover Ground
Thermostat Housing Ground
Battery-to-Chassis Ground

 

First triple check that all sensor connectors are paired with the correct sensors. Otherwise, you may continue to blow good ECUs.

 

I would check input and output voltages on main relay and power and grounds on ecu.

 

I'll second this. Blown Q31 transistor only happens when a couple sensors plugs get swapped around.

 

Yes, that would be from plugging in the Purge/Cut Solenoid connector into the IAT (Intake Air Temperature) sensor and visa-versa.

 

I am having the same issue please help