RB25 hard starting (now with more clues!)

[AZhitman]

For the past couple years, our RB25 (in an S30) has suffered from a hard-start issue.

Basically, it requires 10-15 cranks (not engine revolutions) to start. Eventually, it'll start, idle weakly at about 200 rpm (no kidding), then after 10-20 seconds, it comes up to a normal idle and smooth out perfectly.

No vacuum leaks. Fuel pressure good. All sensors test within parameters. Runs great, once started.

This weekend, I pulled a vacuum line off the side of the Greddy manifold, poured a small amount of fuel into it, blew it into the manifold, reconnected the line, and she started (cold) on the first click.

So, what we're thinking is that the injectors SHOULD cycle once when the key is on (just to "prime" it before starting). They're not doing that, so I have the hard start issue.

I'm wondering if this has something to do with the S30 ignition switch only having 2 "clicks" (on and start) whereas the '94 car the engine came from has three clicks.

Basically, how can I make my injectors cycle once when the ignition is clicked on for the first time?

Thanks guys!

[whoareu]

just so i completely understand on your car theres (off, on and start) and on most others theres(off, acc, on, and start) and you think its this thats causeing the issues? so you think the fuel and injectors arent priming untill your physically trying to start the car? that could be the issue. but id think that once it starts that it would be fine, but i suppose maybe the pump is is taking a second to keep the fuel system adequatly pressurized. why cant you just swap out the ignition from a different car granted youd need a new key but i wouldnt think it should be that hard. or maybe hard wire your pump with a switch.

[Darius]

Where is the pump or relay pulling power from? I don't know how you have the car wired, but some of the accessories are not powered when the key is in the start position, like radio, wipers, etc. Confirm that the fuel pump relay is staying closed when they key is turned to the start position and that the fuel pump is running while the car is being started.

[AZhitman]

Pump comes on with key on, so the system is pressurized at startup.

[Yellow4g63]

maybe pin 45 or 43. 43 is Key switch start signal, lets the ecu know the car is trying to start. 45 is key switch ignition signal.

[USMCgetsome]

i agree with yellow. That's your best starting point.

[AZhitman]

Thanks guys! Thanks to this info, and some input from Gordon, I got it - pin 43 had no power. I ran a temporary tap from pin 43 to the starter signal wire, and she fired on the first crank.

Gonna go so some splicing and soldering - Thanks a ton for the troubleshooting help, guys!