iroczmaro

alright guys i just recently bought a 89 iroc for a project...well it has a little starting problem it will crank all day and will not start but you can pour gas into the intake and it will start and run fine i have replaced the fuel pressure regulator fuel filter plugs and coil...the guy i bought it from said he had the engine rebuilt with a fresh bottom end with a 30 thousanths over bore a 290 cam 194 heads and polished intake thats all i know about it....im leaning towards injectors now but not for sure....so im asking you guys for some help

Ward

iTrader: (1)

Have you checked fuel pressure? Can you hear the fuel pump prime at all, before you start the car? That would be my first guess, injectors don't all go bad at once.

birdtojag

iTrader: (1)

Find out the fuel pressure first. If none, check out the fuel pump circuit. Make sure it is good. Let us know the results to be able to help you out a little better.

iroczmaro

yeah you can hear the fuel pump run and it made 44 psi....when you say prime do you mean when it kicks on then cuts down??..do you think it could be in the ecm

birdtojag

iTrader: (1)

Check to see if the computer if firing the injectors. use noid lights or test light while cranking. If the light blinks (works) then you have an injector problem. If it doesn't light up at all, check to see you have 12 volts at injectors. If so, you have a bad computer - injector drivers may have quit on you.

iroczmaro

ok....thanks alot.....some things are starting to make a little more sense now

irocuroc

I THINK YOU HAVE THE MULTEC INJECTOR SELF DESTRUCTION GOING ON... USE AN OHM METER AND CHECK THE RESISTANCE. IF UNDER 10OHMS THEY ARE TOAST. IF ANY ARE A DEAD SHORT (ABOUT 4 OHMS) THE INJECTOR DRIVER WILL NOT WORK IN THE ECU. THERE IS A DIODE IN THE ECU THAT PROTECTS IT WHEN IT SENCES VOLTAGE GOING THROUGH THE SHORTED INJECTOR INTO THE TRANSISTER THAT CONTROLS THE DRIVER.
HERES HOW TO CHECK THE OHMS OF AN INJECTOR IF YOU DON'T KNOW HOW
http://www.youtube.com/watch?v=_g8PdrT0MCU

VA91Z28

My 91 Z28 had a similar problem not too long ago, but eventually it wouldn't start no matter what... Well, it ended up being a couple of problems, but the main prob was the fuel injectors... they went bad. You do have a TPI set-up right?? 305?? Cuz I have a set of injectors for sale... in fact the same injectors that fixed my car. I put in a new motor now and need a bigger set, but these have about 1k miles on them and they are 21lb/hr Venom injectors (set of 8 of course). Let me know if you are interested and we'll figure somethin out.

Thanks!

NBP

the gtaman

sounds like clogged injectors ,also check your coil wires. sometimes they break inside the cover.

lunaticinaZ

my 91 tpi is doing the same thing. but I have 40 psi fuel pressure and my injectors are all above 10ohms. i have completely drained the gas tank and put new gas in it. and checked the injectors w/noid lights. my car still wont start.

iroczmaro

ok birdtojag...i did finally get to check those injectors looks like computer because there is no voltage at the plugs....and irocuroc i cant find my digital meter to check the resistance on the injectors but i may have found the problem tho.....and va91z28 mine is tpi 350....hey guys are there any kind of relays or anything of that sort to control power to the injectors or is it all computer controlled....the fuses are good...so i may have it figured out....

irocuroc

the injectors should have 12vlts with key on.. the power for these comes from the aux fuse panel, get a test light and start tracing. the power comes from a main fuse in the main panel. the ecm only controls the ground signal to the injectors and has nothing to do with the 12vlts.. i am looking for a schematic to see where the aux fuse panel gets its juice from.

iroczmaro

yeah man that was with the key on and cranking it...both sides didnt have nothing....but the gm manual shows a fuse for each bank of injectors....i just gotta find them now...i dont get much time to work on my car or get on here the way i work so dont think im ingoring you guys....i just gotta make the time

iroczmaro

ok injector fuses good...so i went and got a new computer (not very expensive) and still no power to the injectors....could the wiring harness be bad?? some broken wires somewhere or maybe lost ground

irocuroc

start at the yellow brick road. Get a wiring diagram from the FSM and find where the power comes from. keep following and you will find where the power stops, If it not at the begining its probably not in the injector harness. Make sure you don't have a mouse living under the dash. Those little bastards love wires, Good luck

iroczmaro

well let me tell you this....the most simple things will bite you in the butt...there was a fuse located next to the battery around those relays well i changed that the car fired right up....just wont turn off....ive noticed a little cobbling in that car because the fuel pump runs all the time like its wired straight to the keyswitch...but i just had to pull the coil wire to kill it....shew

jermdm

Mine did the exact same thing. Crank all day but no start. Shoot some starting fluid in the throttle body and start right up. If I turned it back off, it would do it all over again. I had 4 bad injectors. Replaced them with some bosch 3's from FIC and it starts everytime with no problem and runs alot better. Havent had the problem since.

iroczmaro

well guys i know its been a while but after alot of searching and cussing i finally found my problem it was in my wiring harness there were some broke wires some were naked and corroded so it looks like im buying a harness after fiddling with those wires she fires up and runs great and turns off like a good car outta if i do anything else ill fill you guys in