1badzee

iTrader: (12)

Can you guys shoot me some ideas on things that power the injectors? Like sensors, switches, devices, etc? This Formula I picked up would sometimes run, most of the time doesn't. Fuel pump primes and engine cranks, but does not fire. It runs if I spray some carb cleaner or something though (brand new opit and ignition - wires, plugs, icm, coil). Tested for power at the injectors and they don't get any. The injector fuse though gets power (in the fuse block). It could very well be a short in the harness somewhere, but I would first like to try out the easier stuff before I go tracing wires (which I have no patience for). If you guys can throw me some ideas that would be great. First thing I'll look into is VATS (even though fuel pump primes >.<)

Edit: It's a 96 (OBDII) but I tried an OBDI pcm and still does the same thing.

RamAir95TA

iTrader: (2)

The injectors are supplied with 12v constantly (pink wires) directly from the fuse box. The PCM fires them by sending a ground to each injector. The fuel enable command is given from the PCM when the theft deterrent module detects the proper pellet resistance from the key. If the injectors are not getting 12v+ I would suspect the TDM first, then the wiring. Does the SECURITY light illuminate?

1badzee

iTrader: (12)

Security light does illuminate, but not the classic way where it stays lit when you remove the key. The fuel pump primes every time and engine turns over every time. Just no power to injectors. The few times it started up and ran, the Security light randomly turned on while I was driving. It's strange.. I can bypass the TDM, correct?

RamAir95TA

iTrader: (2)

I am pretty sure you can. I'm looking at my wiring schematic, and (theoretically) you could bypass the TDM by applying a 2.5v signal to the PCM (Pin A25, dark blue).

1badzee

iTrader: (12)

Thanks for that info! I just hope it's one of the two. So there aren't other things that control power to the injectors? Like some kind of sensor, etc?

RamAir95TA

iTrader: (2)

From what I can see it goes like this...

Key -> TDM -> Fuse block -> Injectors.

Hopefully Rob will chime in and confirm/add to this.

1badzee

iTrader: (12)

Sweet, thanks man! I hope he sees this as well.

1badzee

iTrader: (12)

Good call. Saw that there is between 0.0V - 0.2V going to that wire (which should be 2.5V). I bought an adjustable voltage regulator, but I guess I have to put in two resistors in-line to get the 2.5 voltage output? Anyone familiar with these adjustable voltage regulators?

slomarao

iTrader: (6)

you could have a little air in the fuel lines. I just went through an issue like this with my 357

1badzee

iTrader: (12)

no.. it's completely narrowed down. No power to the injectors. The fuel feed signal wire is getting no power.

1badzee

iTrader: (12)

Update:

We got 2.5v to the blue wire on pin a25 using a voltage regulator. Anyway, it gets a constant 2.5volts and the car will still not start. Injectors still do not get power, but all the injector power leads are powered, as well as the fuel enable signal wire (thus eliminating vats being an issue). Car just cranks but does not turn over. Gets a strong spark. Any other suggestions?does the bcm/tdm still control fuel somehow even if i bypassed the fuel enabel signal wire? Also, even with the vats plug unplugged, it will still crank the engine, but will not start. That is VERY weird to me, because usually if you unplug the little key/vats plug under the steering column, the car will not even crank, nor will the fuel pump prime - but this one does it even if it's unplugged. Wtf? Bad BCM?

IronOutlaw

iTrader: (4)

Im gonna say start tracing every wire. I had to do this a while back when my car sounded like it was way outta time and it ended up being burnt wires going to the coil and ICM which were caused by the MSD coil not allowing the pigtails to connect securely. I know my problem was nothing like yours but it sounds like your going to have to pull off the wire covers and trace everything.

1badzee

iTrader: (12)

Yeah.. I wish i had that problem. Car wont even start. Ill have to do some tracing. Its just weird that the car still cranks when i unplug the vats plug under the steering column.

1badzee

iTrader: (12)

Another thing, the BCM clicks every 10 seconds or so when the doors are open. Really weird. Can't say I have ever seen/heard that before. I am exhausted of ideas.. Everything that SHOULD make it work (even if rigged), DOESN'T! Logic plays no role in this car.

Rob, are you out there?

shbox

As I said in my reply to your email, the fuel enable signal is a square wave. It requires a 50 HZ signal to satisfy the computer (94-up). If the BCM is not putting this out, you need to have the PCM reprogrammed to eliminate VATS or buy a bypass module that puts out the 50 HZ signal. You cannot simulate it with straight voltage.

Normally, if the 50 HZ signal is not there, you would get a PCM trouble code for the VATS. If you were looking at the wire for normal voltage and not frequency, the result might have been misleading.