I just did an engine swap. Went from 305 to a 327, so here's a list of things I've checked so far.

*6AN fuel lines from frame to throttle body
*New 350 knock sensor
*350 8746 ECM
*350 injectors
*Have spark
*Have 13psi fuel pressure
*Cleaning up another set of injectors in case the current ones are dirty from sitting a few months.

I must have 12v at the injectors because I will get a horrible dribble while cranking, but the injectors stop as soon as I let off the key. So the first thing to check is a definate 12v at the injectors with ignition on. I will also need a continuity check from the reference pin on the ignition module harness to the corresponding pin on the ECM harness. I would suspect a broken wire there due to all the pulling and twisting of the distributor trying to get enough advance on it to get the engine to at least fire.

My main question is... does the ECM pulse the injectors at startup without a reference from the module? Or is it that the injectors are dirty and the only fuel coming out is due to the extra fuel required during a cold start which would explain a horrible spray pattern/dribble as well as the fact that they stop spraying as soon as I stop cranking.

 

During cranking the ECM needs to see reference pulses from the distributor (DRPs) to fire the injectors. The DRPs also cause the ECM to enable the fuel pump via the relay.

The injectors will only fire as you crank the engine. So them stopping as you release the key (on a no-start) is normal.

They should spray a nice cone of fuel while cranking. I would check the fuel pressure during cranking. It may be falling off.

If this swap is in your '88 be careful of which chip you use in the ECM. The f-body '8746 ECM calibrations has VATs enabled. That will prevent the injectors from firing. I figured it being a 350 ECM it is from a Caprice. In that case no VATs to worry about.

RBob.

 

Yes the ECM was from a Caprice. I'm going to put in the other set of injectors and watch the fuel pressure. I'm also going to trace out the wires from the ignition module to the ECM just to rule that out as a main possibility. The fuel pump primes when the key is turned to run.

Now that I think about it, I could be getting the engine to fire up off a pulse or two from the injectors and that bit of pressure that was left in the line. Sounds like I might have broke that DRP wire.

 

It sound like your car is not a vats car and your ecm is from a vats car. Does your car have vats? (black chip in the key) If your car does not and the ecm is Vats enabled the injectors will not pulse. I had this same problem when I put a vats enabled ecm into a non vats car. There is an adaptor available on ebay for 20 bucks that will allow your ecm to work.

 

Update:

Cleaned out injectors... were full of a lot of waxy looking stuff.
Gets a nice cone pattern now while cranking.

Checked drp wire... no opens.
Fuel pump runs for 2 seconds after cranking. Believe I read in another post that I am getting my reference pulses.

So I am getting the engine to start up now, but it still dies shortly thereafter.

I am going to move on to setting the TPS closer to .7 volts, as well as checking the IAC for operation.

Any other thoughts, or have I covered my bases aside throwing a carb on to get it started?

 

TPS setting won't make a difference unless it is way out. Set it for about .54 Volts with the throttle closed. That's all that needs to be done (the ECM auto zero's it).

Have you tried holding the throttle open a little or done any pedal movement to try and keep it running? A bad IAC can cause problems.

Do the injectors keep spraying once the engine starts? Or maybe the spark dies?

Is the spark timing close? Also check the CTS value, a bad sensor will cause all sorts of issues.

RBob.

 

Well, sorry for the unneeded post. Turns out I had the fuel lines backwards. I guess just enough fuel gets through the regulator backwards to appear to have fuel. Switched the lines and it took right off.
I checked everything posted and the fuel lines were my last resort.

Thanks