So I just bought my second 95 z28, I bought it not running, the woman who sold it to me was told it was a fuel pump which made sense as it ran on starting fluid for me (maybe by chance, it wouldn't run for someone else who had looked at it prior) she had also said that she knew it was going out so she didn't leave the neighborhood for a while. It starts and runs sometimes for 30-45 seconds and runs fine when it does. I tested the fuel pressure and got 42~psi. I drained and refilled the gas.

It also has an aftermarket alarm, it seems to never do anything except when the battery is disconnected for 5 or so minutes it will chirp when reconnected. The PO said its been on the car since 2003 when they bought it and she didn't even know it had it until recently so I'm leaning towards it doing nothing.

Now I'm thinking maybe ignition switch, the rpms and relays like to go crazy in the run position, sometimes randomly priming the fuel pump. It seems like the ignition switch is temperamental and does whatever it wants to at times,when turning back from the run position it tried to start once or twice, moisture seems to make it better lol

Anything else that sounds suspicious before I mess with the ignition switch?

 

i would suspect the ignition coil/control module. maybe pick up a noid light for gm injector plug and make sure injectors are being told to fire.

 

After it was on a charger for an hour yesterday it started right up and ran for a couple minutes then stalled and started up a couple more times for 30 seconds or so, I was at a junkyard today so I picked up an extra coil & control module, just put them in and seem to have the exact same problem, not that the heavily used one couldn't be bad too, I'll probably order a new one as well just wanted something today. I'm not sure where to go next, I'm checking to see if maybe there's a loose connection now and try to get a noid light.




Update: Ran again for longer, getting intermittent SES light and car now starts idling up when stalling also,sparking noise under hood (I thought relay at first but I don't know anymore) accompanied by priming of the fuel pump after stalling while in the run position

 

are you looking at the fuel pressure when it stalls/dies? sure sounds like its fuel pump or icm... weird. also when it wont run check the pink wire to the coil to make sure its getting power from the ignition system. i see it has an aftermarket alarm/theft system. take it out,,, all of it. some will cut power to the fuel pump if it thinks your a bad guy

 

Moved the horn thing for the alarm a little looking for wires, also found a little red button mounted under the dash, clicked it a couple times now car cuts power to everything as soon as the starter is engaged, tried playing with the button some more and no change, have to disconnect battery for it to get power back only until starter is engaged then cuts power again, this happened once before but fixed itself when I cut power, could be a coincidence that it happened when I played with the button but I'm not sure.


No I have not looked at the fuel pressure when it dies, i did pump the tank *almost* dry though and it seemed to hold steady the whole time.


You meant check the pressure because of the alarm...oops

 

no telling what pressing the button twice means if anything, need directions. have you looked for a brand and model of the alarm?

 

i took the one that was in mine out. after reading about failures and i was driving out in the middle of no where at the time, wasnt taking any chances.

 

I actually can't even find the alarm, I'm going to look more tommorow, i think I saw some wires behind the glovebox that didn't look factory but I think that's kind of an odd place to put one. I don't think its ever had the opti replaced but wouldn't that be constant misfire and things? Not intermittent no start then running fine and shutting off like someone switched the key off?

 

try and see if its lack of spark or fuel that is causing it to die. best place to start. if its no spark then the opti would be something to look at.

 

its most likely under one of the panels at the bottom of the dash. mine was up behind the steering column, had to take the panel off the underside by your feet to get to it. follow the wires from the horn thing...