Help. Ijnjectprs aren't firing
 

I need help,

i have a 2004 5.3 with a CBM 450 cam, and blue springs. I have an LS2 intake with a CMB adaptor plate to a dbw truck throttle body. My harness is a CBM. The throttle works , I have had my blue / green computer flashed. Engine will not run. If I " prime" the manifold it will fire right up, and burn off the fuel, then quit. I have 12v to all 8 injectors. I have 12v at the blue connector for all 8 injectors. I don't know what to do , any help Is appreciated

Check your crank position sensor. I had that problem on my ls6. Was a brand new sensor from summit and it was bad. Easiest way to tell without hooking up an oscilloscope is to see if you have a tach signal. Mine wasn't showing a tach signal while cranking then I replaced it with a 15 year old sensor and cranked right up

Ok thanks.
i replaced the crank sensor that came with the engine with a brand new Delphi " just to be sure". I'll put the original in, and give that a try

Could also be the security system. It will allow the engine to run about 1 second and die.

If it's not that it's a cam or crank sensor issue. The computer flashes the ground to the injectors to fire them. So you can hook up a noid light and watch for injector fire or use a test light on the ground wire at the injector plug and watch for it to flash.

If you have a graphing meter ( I use a fluke ) you can tap into the signal return wire at the cam and crank sensor and watch for the graph to flash. The signal is too fast for the numbers on the screen, that's why you need an oscilloscope to watch the wave form pattern, or a graphing meter. Oscilloscopes are several thousand dollars, but a graphing meter is a couple hundred so I bought a graphing meter for that reason (to watch cam and crank sensor signals).

I swapped out the crank sensor with the original, and no change. I'm going to wire up the original tach thru a Dakota digital converter box to see if I have a tach signal

Try the tune/diagnostics forum?

I don't know what car you have or how it's wired but on most vehicles the tach doesn't move during cranking.

78 trans am with ls6 and a standalone harness. I checked it again today and I do have a Tach signal while cranking on my OBD reader

yeah you may see it in a scanner, you said you were gonna hook up the original tach and check for signal, I thought you meant you were gonna watch the tach itself.

My mistake. Not sure about tach but def on obd scanner

Hi, just saw this. Can you please give Sean a call at 909.291.7550 ext. 2004.
Have detailed info ready and we may be able to help you out. Thanks.

Yes I am working with Sean. I appreciate all the help so far.