50chevy

iTrader: (2)

I just installed a 408ci / 4l65e combo in my 1950 Chevy truck. The PCM got a baseline tune to get it to run speed density until I can get a few break-in miles so I can dyno it to get everything perfect. It has had the VATS removed. I can turn the key, fuel pump gives 58 psi at the rails, and it will start for a second and die as if it running out of air. I manually open the throttle a little, it will rev up some, sputter and die a few seconds later.

Here is what I found after checking sensors:

TPS: 5v between grey and black (ground)
Blue 0.16v to 2.2v (NOT CORRECT!) swapped sensor, same result

MAP: 5v between power and ground
Light Green: 2.2v with key on (back-probed sensor)

It seems as if my sensor signal wires are giving the PCM a much lower signal that what it is required.
I am getting 5v and ground from PCM

Also, removed IAC motor with wiring plugged in, turned on key and the pintle fully extended out (as to shut off all airflow). Is this normal?

I ran a dedicated ground from the engine to battery - no difference.

Old Geezer

iTrader: (3)

Fuel pump continue to run when you release key after it starts?
Batt volts is?

50chevy

iTrader: (2)

The fuel pump will prime for 3 secs and shut off with the key on. If I try to start it, it will runs for 3 more secs after the engine dies. The battery has 12v and cranks over the motor quickly.