horrors

[wyldcdn]

after 20 min of idling it will shut off. Ran scanner, no codes. Used noids on injectors. No light. No spark. Swapped in fuel pump. New icm and new coil. It did blow two fuses, open for ignition and one for one set of F.Injectors. I don't know if the fuses went when i swapped the injector rail and reg. Also new spark plugs they were fuel soaked black soot. New O2's both sides
so re-cap what i found
1. no spark
2.no fuel at injectors
3.no codes present or history
4.used noids on injector harness, nothing.
5. Two fuses perhaps related or unrelated one for ingnition and one for half the injectors
6.new fuel pump, filters and reg.
7. one side of the O2 was at 444, other side was at 4

I'm fine with doing the work, I'm fine with buying a part. I just don't know what direction to go anymore

[96LT1355Z28]

I'm kinda confused by what you wrote, will it start and run for 20 minutes then die and not restart intermittently. Or did it run for 20 minutes, die and now won't restart?

"I don't know if the fuses went when i swapped the injector rail and reg."
This should have noting to do with the electrical system unless you are missing the cover to the engine compartment relay box and somehow got somthing it/on it.

What did you do or change before this happened?

Does it currently have fuel psi, just no spark or signal to pulse the injectors?

It sounds like your issue is directly related to the blown fuses. Exactly which ones blew? What mods are done to the car, how many miles? Sorry for the questions just trying to get deatils to help!;)

[krayzie7th]

yea we need more details. What year?

[windsofthor]

Check the ground wire pin out (2) on the red pcm connector. See if it's damaged.

[wyldcdn]

sorry it was late when I posted.
94 z28. basic bolt on car. Cold air, Granatelli MAF, lt4 KM, full exhaust, electric cut out, hyper teched yeears ago. 342's 2800 9.5 vigalante stall. Nothing serious
With a possiable nitrous cam install back in '95. It will fine, run great for 15-20 ,then shut off. After very long extended cool down it will fire back up like nothing ever went wrong.
This problem just surfaced out of the blue one day. Fired up went to accelerate and it would misfire til it got to operating temp. Then was fine. Next time it did it It shut off under WOT. After 10 min fired up. I thought it was bad gas due to how fast the problem surfaced. I pulled fuel filter was dirty so I diagnoised bad fuel swapped filter and pump. It was not the problem. I swapped coil thinking age and heat go to it. Next day ran great no misfire. I had it idle later on while i was cleaning it. It went very rich and died. Thats where things went odd. I swapped ICM out thinking it was heat related and the reg; since I had a spare rail with everything on it. Then it wouldn't re-start. Found the two fuses blown. Swapped em. Car fired up ran great as it ever did. After 15-20 min it just dies.
I hope thats better description

[Z28pr0jekt]

That definitely sounds like the icm but since you replaced it I suppose that isn't the case, I'd try the coil.

[wyldcdn]

coil swapped
tried a msd, brand new and factory

[Z28pr0jekt]

Ah my apologies, missed that in the first post

[96LT1355Z28]

You did try swapping the ICM with a working one?

Check the opti harness on the passenger side of the fuel rail and ensure it's plugged in and the wires aren't damaged. It's possible somthing happened to it when you swapped rails.

[dts300z]

EDIT: sorry did not see above post

Check you opti sub harness for corrosion. I had a similar problem and it ended up being a corroded opti harness which intern destroyed the low voltage side of the opti.

This one kicked my ass for several days since I had replaced everything and never thought to check the opti sub harness and it destroyed a brand new opti.

[wyldcdn]

swapped opti harness , no changes. Tried three ICM's no change. Gonna start on the computer harness, starting at red plug and pin 2 for ground make my way thru it all. Gonna be a pain.

[dts300z]

When you pulled the opti harness did you look into the connection for corrosion (on the opti side)? I say this because thats where mine failed and one of the pins on the opti side actually corroded away and somehow had an intermittent connection that allowed it to run for 20 min. or so after it sat for a while.

Good luck!

[wyldcdn]

no corrosion

[wyldcdn]

something i never thought of
I've owned this car for three years coming up
since I've bought it. The security light has always been on. I only have one key. No chance the security is kicking in after running is there?

[96LT1355Z28]

I think it would prevent it from starting all together. Have your tried loking here for some options this is a great rescource site!

http://shbox.com/1/4th_gen_tech1.html

[Z28pr0jekt]

Usually when the security light is on the car wont even crank... you can try it though

[wyldcdn]

on the site gonna use the schematic to trce stuff great site