I've got spark, it'll only run on starter fluid.

I took a test light and both wires to the injectors light up on crank and when it runs on starting fluid. Neither seem to pulse.

There is no park neutral safety switch hooked up and neither Blue34 or Blue72 is hooked up to anything.

700r4 Trans.

On the plus, no smoke and runs smooth for all 2 seconds at a time.

We have fuel to the rails, and at least enough pressure spray pretty good when you depress the bleeder valve.

 

Sounds like the injectors are stuck/clogged. Take them out and clean them and you should be good to go. There's a lot of ways to clean them, but I usually soak them in Seafoam overnight.

 

thats the way I was leaning but seeing no pulsing with the test light kept me from pulling them out and apart.

 

It's dark out so pulling them is gonna be in the AM.

IF that doesnt work, what are some possible causes to get spark but no fuel injectors pulsing?

 

Harbor freight $85 heated ultrasonic cleaner with sea foam for an hour or so. Works every time.

 

So not detecting a pulse with the test light is normal?

 

You need a noid light, a test light usually won't work

 

tried cleaning and testing them, seem good to, still no start

Hooked an old sunpro tach and ran it to green pin 10 for engine speed. I don't see any rpm on 4cyl or 8cyl mode while cranking. Would a bad crank sensor allow it to spark but no fire fuel injectors?

 

I had a similar problem with mine this week. It was IAC was stuck closed not letting any air in for it to start and idle off of. Take the IAC off and unplug it, if its pushed all the way out thats your problem, try and push it back in, reinstall it and it should fire right up

 

well even with TB wide open it wont start, there is no fuel getting into the cylinders

I have ~60psi at the rails

 

Chk your PM's.

 

Have you tried tuning Vats out and maybe enabling the fuel/resetting the pump. I swapped a oem 5.3 complete drivetrain one time from a totalled yukon and it wouldn't start. Safety feature disabled fuel after airbags deployed. Reset that and fired up and ran perfect.

 

Okay with a noid light I'm getting not signal to the injectors.

The computer was reflashed to remove vats and be drive by cable. I believe the tune is like an 05 express van as it was the latest to have a cable throttle body. Blue green connector harness worked through by me and using the pinouts found here... http://lt1swap.com/2004vortec_pcm.htm

The engine itself is a 2000 lq4 and I'm running a 700r4 behind it

 

Have you checked to see if you have 12 volts going to one side of the injectors? Be sure to check it will all the injectors unplugged or you will get a false reading. If the VATS was still working then it would at least fire for a second. So take that off the list for sure. Is the battery dropping below 10 volts while cranking?

 

What vehicle is this engine transplanted into? Some of the older GMs did not have 12 volts from the ignition switch while in the crank position. As Sean at CBM said check for 12 volts at one side of each injector plug both in the run and crank position.

 

the lead powering up the relay to powerup the fuseblock and computer has power on acc/crank/run it is off the acc hook up on the fuse block in 70 cutlass.. I have power to the injectors when it is cranking. I have 12 volts in run and I was getting 10.8 while cranking when I checked but the battery could be getting weak, it's done a lot of cranking lately. Sounded like the starter was still gtg though. There was no low batter whine to it.

I wired up my diagnostic port today and scanned it. I got a P0107 for low voltage on the MAP I looked up the wires and I somehow skipped wiring in the signal wire for it. Got that taken care of erased the code cranked the car up same issue as before. Scanned the computer again and it is not throwing any codes.

 

Are you certain that you have power going to everything, while you are cranking the engine?

 

Pretty damn certain. I'm just really puzzled how it is getting enough spark to run on starting fluid but absolutely no signal to the injectors.

I'm going to fiddle around with it one more day then probably trash it and just get a pro-done harness & a new computer. I was stuck at this point early this year for a week straight and now 3 days so far now. I'm in Texas and the car is in Georgia been a side project since highschool with various engines and transmission swaps as a general money pit weekend race & wrench car and always kept at the parents place while I was in college and such. Need to get it going soon here and move it out west with me and the wife.

I've got A/C, new carpet, 3point rear and front seatbelts and a chassis harness to install as well in a 6 week time table. I was thinking I was just overlooking something stupid and simple back in February but I've checked all my grounds and done all I could think of. I was really really hoping that stupid MAF signal wire not being hooked up was the problem. Tired of my pile of **** grandprix gtp (what is with GM making good engines but terrible cars?) giving me issues and looking to make this my daily driver again but with more creature comforts and more safe family car-ish with a side of *****.

 

If the injectors are not getting the ground signal from the PCM it's either still stuck in VATS a bad PCM or all 8 of the wires are damaged.

Since the chance of all 8 wires being bad is pretty slim, I'd get the PCM back to the tuner.