bigbear807

So, I'm in the garage diagnosing a No Start situation with my 89 Iroc 5.0 auto conv.

28k original miles with the original fuel injectors.

I checked spark at the plugs, Good.
I have 46 psi fuel pressure at the rail and fuel pump is running.
full tank of gas.
Injector fuses are good.
I have 12 volts at each injector.
I checked the resistance on each injector: they're all 17 ohms, except injector #1 which is 3.8 ohms, and #8 which is 8.4 ohms.

so, next on my list to check is the injector pulse from the ECM.
I start with the #1 injector, pull the connector, set up my test light and get my wife to turn the key.

I expect to not see any pulse. But immediately, the car turns over, starts and runs great (except its only running on 7 cylinders). And I'm getting an ECM injector pulse on the connector.

The interesting part is now that it's running, i reconnect the plug to the injector and it immediately dies. Won't start with it plugged in, but if I unplug the injector it starts and runs fine.

That injector is bad an I'm going to replace it, but I've never heard of that being the reason for a No Start. (prior to today )

Can anybody explain this? Is it just grounding itself and preventing ignition??? Is it bad wiring?

kaos420

yes it will have a no start issue.yrs ago my buddies car he bought had that same problem got it for almost nothing cause the guy couldn't figure it out an we tested the injectors an seen a dead one replaced them all just cause car fired up an ran awesome..

Bob88GTA

iTrader: (2)

bigbear,
Check out Southbay Fuel Injectors on here. You can get a 10% member discount for 8 new Bosch injectors for about $160. Great group to deal with!
Good luck!
Bob

bigbear807

thanks guys,
I guess I really want to make sure i don't have a wiring problem.

bigbear807

Alright, I just ordered a nice Bosch set from SouthBay fuel injectors. $180 for the injectors, gasket kit and o-ring kit.

I'll let ya know how it goes.
Hope there's no other wiring issues.

Bob88GTA

iTrader: (2)

Well you can remove the next injector plug and try it on the first injector and see if it stalls. If it does, #1 injector is bad. Worth a quick shot. The injectors are "batch fired"

ULTM8Z

My guess is there's an internal short on the injector. Have you put an ohmmeter across it?

Bob88GTA

iTrader: (2)

he got 3.8ohms on #1

bigbear807

Yes, it’s 3.8 ohms cold, and less than 1 ohm when warm.
What does that mean? Is the coil inside shorted ?

Bob88GTA

iTrader: (2)

Weak injector (resistance too low) which has shorted winding's or one that has an open in it's winding's (infinite resistance).

Josh52784

if I were you I would have went with AC Delco I have always had problems with Bosch in all my chevy's I had a Tahoe went with the best Bosh plugs and would always foul out at least 2 plugs if you get the problem again in 6 months it's the brand GM runs better on AC Delco

Bob88GTA

iTrader: (2)

Josh, were're talking injectors here..not plugs. Yes, AC Delco Plugs are great in Chevy's

ULTM8Z

Since all 8 injectors are ganged together on a single +12V circuit (hence the "batch fire" on OBD-I TPI's), the shorted injector is pulling the 12V down and basically shutting down all the other injectors.

bigbear807

that makes sense that it shuts down the other injectors.

IROCgiraffe

iTrader: (3)

Go SouthBay.... replaced mine with a set I purchased from them a few years ago.... no issues