No Injector Pulse

[Tyree]

I am getting 12 and 15 pulsing on my service engine light. I cannot get the injectors to fire when trying to crank the engine. I just put this engine in and did all the wiring to the computer and sensors using the diagrams on this site. The engine is a 94' 350 and me and my buddie just did this on his truck in Jan. Now Im doing my own. Triple checked everything and still not getting any gas when cranking. I have the purple starter wire tied to c9 as indicated in the schematic. What could be the cause of this? I even replaced the cap and rotor and verified I am getting spark. Fuel pump primes when power is applied to ECM. I am lost now. Any suggestions out there? What could be the cause of the injectors not shooting gas? I am lost at this point and need to take a break off it for a few hours?

EDIT: EagleMark split from other thread...

[buddrow]

I am getting 12 and 15 pulsing on my service engine light. I cannot get the injectors to fire when trying to crank the engine. I just put this engine in and did all the wiring to the computer and sensors using the diagrams on this site. The engine is a 94' 350 and me and my buddie just did this on his truck in Jan. Now Im doing my own. Triple checked everything and still not getting any gas when cranking. I have the purple starter wire tied to c9 as indicated in the schematic. What could be the cause of this? I even replaced the cap and rotor and verified I am getting spark. Fuel pump primes when power is applied to ECM. I am lost now. Any suggestions out there? What could be the cause of the injectors not shooting gas? I am lost at this point and need to take a break off it for a few hours?

EDIT: EagleMark split from other thread...

GROUND, GROUND, GROUND!!! Sorry, have seen it too many times. Check all your grounds for security and connectivity. They are vital to operation. If it is a transplant truck then definitely verify ALL grounds. Need good ground from battery to-->Body, Engine, Body-to-Engine, Engine-to-Frame. HTH

Buddrow

[EagleMark]

Well the injectors also need 12 volt power going in, then the ECM grounds to fire them. So do you have fused 12 volt power to injectors?

[Tyree]

Eagle mark. Thank you or your reply. I have 12v power going to injectors on a switch. I have my ecm and dist on a switch also. I have 3 ECM grounds going directly to a pigtail on the negative battery terminal. The starter wire is to the block. I will add two more fat wires from the block to the body and a fat wire to the negative terminal to be safe and go from there. I have nearly given up and ran out of time. I will try again on Thursday morning. Thanks again. Its driving me nuts because I have done this before. I got a couple of drips out of the injectors about three times out of about 40 tries.

[Tyree]

and thanks buddrow

[steveo]

it's always the same, the injectors are powered constant, the ecm switches the ground, the ecm does so based on input from whatever reference it has; cam sensor, distributor or front mount, or crank sensor. if your ecm isnt trying to ground the injectors, you either blame the ECM, or you blame that positional refrence.

[EagleMark]

Those grounds would be better off to say... intake manifold or block. Then negative batt terminal to block. That is the way factory has them wired. I forget why grounding to batt is not a good thing...

As for power on stuff... I'm guessing this is a conversion and they always bring up issues. The way I like to power an EFI system on an old carb vehicle is an extra relay. Use the wire that went to points (with resister removed) to turn on this main EFI relay, then let that relay power on other things as well. I've seen them done with switches as you described but they always seem to have issues. Maybe it's not getting power at right times? Like one guy ran a switch instead of a fuel pump relay and turned it on manually, well sometimes he forgot, if you let it work like GM intended then when key goes on, fuel pump primes 2 seconds and goes off or stays on if you go directly to crank, then the crank wire also gives ECM signal at correct time, remember there's another wire off fuel pump wire back to ECM so it knows fuel pump is running. He had all sorts of strange starting issues. All we did was take out the switch and wired in the relay as it is stock and he never had another issue.