I'm stumped...truck no worky.

[EagleMark]

In the $OE thread is some good wiring diagrams, but in $0D thread is pinout diagrams with key on volatge check. Something is wrong. Even if you chip was bad it should run.
http://www.gearhead-efi.com/Fuel-Inj...Information-OD

[907 Chevy]

I checked pickup coil output before I installed the dizzy so I know I'm getting DRP...I'll see if I can get someone to give me a hand so I can check for spark tomorrow.

I did try two different ignition modules though and one was known good, yeah I'm running out of ideas...fuhhhhh!!!

[907 Chevy]

I'm pretty sure I have a good grasp of how the ignition system works on a TBI system...what am I missing? I know I have a good ignition module and a good pickup coil, what else is there? I'm getting 12v to the injectors, I know they're functional...I'm getting frustrated.
Something that probably doesn't matter, but I've been wondering about...I relocated the ignition coil to the fire wall, does the coil need to be grounded to the engine to work?

[jim_in_dorris]

Do you have access to a noid light? Check for pulses at the injectors. If you are getting pulses, you have a fuel delivery problem. I would suspect the fuel pressure regulator in that case. Fisrt check for pulses at the injectors. not fuel, electrical. The ecm should be driving them to ground.

I reread your first post, are you saying that when you jumper the injectors directly they spray fuel?

Big block IAC's are wired differently, but I don't think that would stop fuel delivery.
Look at voltage out at TPS. is it around .45 volts KOEO not touching the throttle?
That also should not stop fuel.
The startup for fuel comes from the distributor and doesn't switch to drp until it starts. I have to agree that it is a wire you are overlooking

[pmkls1]

It sounds like a wiring issue I agree, but the pcm still has to ground the injectors while cranking. Considering the fact that you can't communicate with the pcm along with the other symptoms, it sounds like there is a faulty power or ground circuit for the pcm. It also sounds like this problem began before the new TB was installed although I would still check the 5v reference circuits with the sensors unplugged. I can't get to a good wiring diagram at the moment, but considering all present symptoms it points to something pcm related like wiring, fuses, relays, terminals, ignition switch, etc...... Since the ignition operates in bypass mode during cranking it should still have spark while cranking.

[907 Chevy]

I can get a noid light at one of the local parts stores, I'll see about getting one today.

When I jumped the injectors no fuel came out, but there was no pressure in the system when I jumped them. I had considered a fuel delivery issue as well, but fuel pressure is right where I set it, which tells me that fuel is reaching the regulator just fine...right?

I'll check PCM ref voltages after work today and while I'm at it, I'm just going to start over and recheck everything...grounds, fuses, etc etc.

Thanks for all the help guys.

[907 Chevy]

Alright, just a quick update: I picked up a noid light at lunch and ran home to check things out...the PCM is not commanding the injectors to fire. I was already pretty positive that was the case, but it's good to make sure in any case.

I didn't have time to test anything else, but will get to it tonight after work...

[davo727]

My buddys truck did this with a new harness and I found that the TPS wiring was backwards and the PCM thinks its at full throttle like you are trying to clear a flooded condition therefore wont fire the injectors. Corrected tps wiring and started right up.

[chevmasta]

can you pour some fuel down the intake and will it start and run?

[907 Chevy]

can you pour some fuel down the intake and will it start and run?

I shot some starting fluid into the intake manifold and the engine made an attempt to start, well it coughed a little bit at least. Lol