Well, I don't know where to turn on this one guys. My Z was running just fine until i decided to play with the fuel pressure the other day.

I did a plug change also and went from 46 to 50 psi and now the car wont even start. Let me give you some background info. A while back (like over a month) ago i was at the track and was spraying approx 150 shot. The car ran like crap...HUGE backfires, etc etc. I got back to the pits (car ran fine/strong on motor) and DID NOT check the plugs like I should have b/c I am a complete a-hole!! Anyway, fast forawrd 1 month. Car ran great the whole time up until yesterday when I decided to change the plugs (6 out of 8 were blown to heck and the tips were all busted off, etc) Well, thats a damn shame and hopefully all that got spent out of the exhaust and not stuck in a piston

So, here is how i diagnosed the sitution. (Mind you I am a GM /ASE certified technician and have been wrenching for years and know f-bodies inside and out LOLOL)

SPARK:

1. Check and re-check and RE-CHECK spark plug wires for propper positioning. ...OK, but no start
2. Pull dist. cap and check cap/rotor...OK, but no start.
3. Pull a few random plug wires and check for spark...Ok, but no start
4. Pull same plugs and attach to wires and check for spark...OK, no start
5. Pull cap and rotor AGAIN and replace amplifier module (it is 10 yrs old anyway, and i wanted to throw my MSD piece on regardless....OK, no start
6. Pull #1 plug, get TDC and check rotor position, check mark on balancer and check to see if it lined up at 0...all OK, no start
7. check coil...good, no start

Conclusion: it has spark and timing is good!!!!!!!!!

Fuel: OK, so in my FP tinkering I went WAAAAAAAAYYYYYYYYYY overboard on accident and bumped it up to like 80 psi once. No big deal *I THINK* b/c i didn't start the car or anything. I was just checking by "ignition on" and letting the pump prime, but not attempting to bump it over at thast point. So I say holy S%$^ and turn the key back and re-adjust...got it to 50psi eventually LOL.

Fuel diagnosis:
1.Check FP at shcrader valve....got 50 psi..OK, no start.
2. So it cant be a fuel filter or kink in any lines or anything "BEHIND" the shcrader valve.
3. Whip out electrodes and plug into injector harnesses...like 6 of them (2 of them are a beeeatch)....bump car over and watch the lights. All are flashing properly, etc...OK, no start
4. I have an extra MAP sensor, so i swapped that out...no start.
5. All vaccumm lines are where they need to be, etc etc etc

My question is>> could I have seized up the injectors by nailing them with all that fuel pressure?????? Can that happen?? I never heard of it in this manner before.

I hardly think so but im lost right now guys????????

I tried spraying some starter fluid in a couple cylinders and TB, etc...nothing

I checked the computer, pulled it down, switched chips, scanned for codes...nothing


the motor spins but it wont fire!

whats the deal here???

 

BTW: from another thread I belive my injectors are the "Multecs" Whatever signifigance that might have for ya

 

You probably already checked this but for what its worth do you have compression? You mentioned some nitrous and backfiring, maybe something went bad and now its rearing it ugly head. Hope you figure it out, sucks when that **** happens...