RB25DET will crank but no start. easily starts by push starting. runs perfect, need i

[LJBS13]

I have a series 2 rb25det swapped into an s13.
Gt3071r, 550cc dw injectors, freddy intake mani. R.S Enthaply ROM tune.
My issue is with starting it. It will not start by just cranking the starter i have to pump the accelerator while cranking and sometimes it will fire up. This problem has slowly gotten worse ever since i did the swap a few years ago. It would not start in the summer, then it stopped wanting to start when the motor got warm and after i did my turbo upgrade and rom tune it now happens whether motor is hot or cold in all weather. If i barly roll the car and pop the clutch in gear the car will fire right up with no hesitation every time.
-what is the difference between starting the motor with the key compared to push starting it?

-I have replaced the coolant temp sensor, checked voltage at the harness, it checked out at 4.9v.
-verified 12v at pin 43 going into the ecu, (start signal)
-replaced iacv, aac with new unit. Made no difference. The idle is fine by the way no issue with low, high, or idle hunting.
-using a brand new wiring specialties plug and play harness so all new connectors plugs and ground wires.
-proper spark plug gap
-ive increased the fuel pressure at startup, no difference.

Ive read through the FSM and feel like ive tried everything i can to my ability. My last resort is taking it to a shop. So any input or ideas are welcome, thanks

[Kingtal0n]

When you push the key to "start" position, many of the vehicles electronics shut down. It sounds like maybe your computer is on one of the power circuits which also "shuts off" while you are cranking, or it is losing power during cranking for some other reason, likely a relay (either mis-wired or old/bad). I would start with the "ECCS" type relays in the car, things that power the computer, maybe try hardwiring the many 12v computer inputs to permanent battery connection for a diagnostic cranking.

I've seen an ECU do this by itself also, so it could be a bad computer. It would reset when you go to start, taking an extra 5-12 seconds to "reboot" (it was a standalone) and in the mean time you are there holding the key.

[LJBS13]

Thanks for the reply, im using a rom tuned z32 ecu specific for my setup so i cant really try another ecu but i can say it had the same issue when the motor setup was stock and i was using a stock rb25 ecu. As far as the relays im going to get ahold of 2 "good" relays to swap in to the egi and egi pump slots and see if it makes a difference as you suggested.
I've narrowed the problem down to fuel related. This weekend i tested the fuel pressure right before the rail and verified proper fuel pressure at prime and while cranking. So its getting the pressure. I cranked the car without starting and removed a spark plug and it was bone dry no fuel on it. I also verified spark by leaving the plug out and connected to the coilpack and cranked the car with the plug close to the heat shield and it produced an arc. Also after this testing i put everything back to normal and tried to start it and it just cranked. I removed a vacuum line and poured a little gas down it into the intake mani and cranked the car and it fired up. I repeated this process one more time just to make sure and it did it again no start, add fuel to intake mani and it started. I removed the harness connector going to the injector plugs and its supplying 12v to all the plugs when ignition is "on" and "start". So im assuming something is going on to where when i try and start the car by cranking the injectors are not spraying

[madd]

Leaking injector?


Sent from my iPhone using Tapatalk

[gaz_moose]

ive had problems like this before.
check your engine earth lead.
try running a jump-start lead between the engine and a good chassis earth to test it.

[RB25GUY]

I've had this problem before and it was the maf that was bad along with the fuel pump