my 1989 iroc 5.7 is giving me a headache i have had the car for 14 years it has many add ons cam. heads,throttle body,injectors,etc. i do not drive the car very often but do keep up the maintainance.the problem the other day i changed the oil charged the battery,etc for the summer .i let the thing run for about 30 minutes then parked it .the next day the car will only crank.it has fuel pressure to the fuel rail has spark to the plugs ,but no power to the injectors i checked them with a noid light ''test light''. any help would be great

 

im having the same issue, does your fuel pump prime? maybe a bad ecm? i forgot but if if you have no oil pressure the ecm prevents either the fuel pump or injectors from working... I can't figure mine out either.. but i havnt even checked with a test light yet either..

 

Check the INJ1 and INJ2 fuses.

 

i knew thier were probably fuses.. my car has been sitting all winter, i had some bad condensation in the car.. whats the chances those two fuses died? i havnt noticed anything else failed..

 

Did you test both sides? Each side is protected by a 10amp fuse.

 

thanks for the ideas i did check the fuses they were good i just went through any connectors i could find fuse block,under hood,distributer,ecm,etc. don't know for sure what i did but it started.i wish i would have found something so i would not have to worry about it.thanks again

 

My daughter's Festiva started blowing a 30amp main fuse, I checked everything. I pulled all the fuses out of the fuse box and put them back. The main fuse hasn't blown in a month, before it would blown as soon as the engine started. I'd have felt better if I had actually found a short.

 

OK im gonna be really smart here so hang with me. white 1, I talked with a gm mechanic today, he said this, with the positive noid light hooked into the positive on the harness, hook the negative to the engine itself then crank the engine, does the light, light up then? if so, you need to check your pickup coil, as I do. remove your distributor cap, disconnect your pickup coil, and stick a multimeter into the pickup harness. set the multimeter on AC and while cranking the engine, the multimeter should read 200millivolts. if its less or none, then the ecm is not getting enough signal to know the engine is cranking, theirfor, not firing the injectors.

hope this helps you, i'll be testing mine tomorrow.

 

The injectors are connected directly to the fuses which are hot in run/bulb test/start.
With the noid light connected to ground and the key on it willl light because you've effectively bypassed the ECM.
The ECM switches the ground not the positive, the only thing that test will tell you is that there's 12v to the injector harness connectors.

 

exactly my point. topic was no power to fuel injectors. this method will test if thats true or not.

 

My post was only to show that it isn't neccessary to crank the engine. some one might conclude that the ECM is at fault because it's been bypassed.

The ignition ru/bulb test/run postion is protected by a fusible link at the starter, but you'd notice other things not working, like the radio. May be a broken wire in the harness.

 

th ground for the injectors runs to the ecm then back up to the heads? is thier a seperate wire for each bank of injectors?

 

Yes, the ECM has 2 driver circuits to drive 4 injectors each.

 

Since it's an '89 I'll throw it in... Does the Security light come on? Is VATS still enabled? Condition of the key chip?

 

LOL

It does sound alot like VATS dont it Red?

Been there done this on a friends 91 :-)

later
Jeremy

 

not vats, i burned a chip with vats disabled and no luck, thanks for the idea though.

 

Not your thread. I knew you had the burned chip.

 

my bad sorry, was on a frantic search to get this thing running!

 

traviz did u ever find out what your problem was?

 

I have a 89 iroc z 350. Ive replaced all my injectors because they where out of range with a ohms test. the car ran befor I changed them and now it cranks,gets fuel pressure ,fire, positive to the injectors but no negative side from the ecm on either back. Ive checked for a negative all the way back to the passenger fender at the wire loom and still no negative.is there anything else that tells the ecm to send the negative signal to the injectors or is it my only option to change the ecm?

 

Yes, there are a number of things but it's probably best to start your own new thread about it.

 

I'm new at this and honestly I have no idea how to start a new thread.if you can tell me how I would greatly appreciate it and thanks for your help.