CR/VTEC EG 93 Si, Was crank no start got to start and run. Replaced fuel pump but that wasn't the only main problem. Curious now and can't find an answer anywhere or spec or close. KOEO fuel pump primes for 2 seconds and will peak around 45PSI and after 5 minutes or so it has bled down to 35PSI. I crimped off the return line from the fuel pressure regulator with hose pinch off pliers and the pump ran and dropped to 0 rapidly. Not sure where the pressure went. I can't find any visible fuel line leaks anywhere either. Replaced Walboro 255lph fuel pump with an AEM 50-1000 320lph pump. Vehicle lost the entire tune in the Hondata S300 (Apparently a battery is installed in the V1 S300 that keeps info in the ECU) but I can still upload and download to it. When I start the engine my PLX M300 wideband says 14.7 or so and rapidly heads toward lean towards 19.0 and I end up shutting the car off. Also KOEO the wideband will read stoich and then gradually head towards reading full lean. I've emailed PLX about this they're thinking I may need an O2 sensor instead of a whole wide band. I'd like to restore the car and keep it and have it run how it used to and eventually be nice again. JBTuned fuel lines, hangar, pump, and relay and wiring is $$$$$.

Lots of direction/misdirection on the wideband also. Keep in mind I built this car over a decade ago.
ECU Wideband Setup Guide by Xenocron : Xenocron Tuning Solutions (my numbers for lambda voltage conversion were completely different in my backup maps I had on a thumb drive)

https://www.hondata.com/forum/viewtopic.php?t=17147 - Hondata article about PLX M300 and how to wire.

How mine is wired -
PLX M300 Wideband Ground/black wire is at connector D Terminal 22 G/W wire. (Sensor Ground 2).
PLX M300 Wideband Power/RED wire is connected at connector A Terminal 25 Y/B wire (IGP2 Powersource)
PLX M300 Wide Band Gray Wire is connected at connector A Terminal 6 O/B wire (Primary 02 Sensor Heater Control) (*Heater control is disabled in Hondata S300)
PLX M300 Wide Band WHITE wire is connected at connector D Terminal 14 (Primary O2 White Wire)

Hondata data monitor A/F matches the PLXM300 also.

 

I think you need to start by upgrading your Hondata. The V1 will no longer work at all once the battery is dead. Time to upgrade to a V3, or contact motoxxxman on here to repair the V1.


The fuel pressure drop doesn't seem that abnormal to me. The only concern would be if it is leaky injectors, in which case you'd have symptoms of flooding out. My fuel system has never held full pressure for very long with the car shut off... why would it need to?

 

I hope that isn't true. I called Hondata and we spoke on the phone. They're the ones who suggested trying to download or upload from the ECU and when I did I got the engine to run. ECU still communicates with PC ok. Perhaps they can repair the ECU.