Do you have access to diagrams? That would help. Basically, there are two large red wires that supply power to the switch. They should have power at all times. Accessory power from the switch is a brown wire(should be hot in "accy"&"run"). A brown/white wire and an orange wire power all of the "ignition on" systems. These wires should be hot in "run" only. A pink wire carries ignition power to all of the engine control systems and should be hot in "run" only. The large yellow wire is the starter activation circuit and should be hot in "start".

Is there a particular problem you are trying to solve? Also, the wire colors I gave are for the 86 model. While most will be the same for 91, there may be some differences.

 

we had a 93 Camaro do that same thing and it was the spark module.

 

No updates on injectors or engine starting yet until i first check plugs for fouling and also get new injectors installed...
But i agree with Doc that you really need wiring diagram to troubleshoot ignition system...what is your car doing that you ask about key/switch system? I did voltage drop test across yellow and one of red wires to test ignition switch...which should be below 0.5 volts...when cranking engine...think mine was 0.223 V.

 

In middle of injector swap now...i read page that said i needed a line wrench to disconnect fuel line connectors or i could strip threads...anyone ever done that with regular open end wrench?
Also, whats best way to get old gasket off parts? Don't want to use metal and gouge metal...maybe soak in solvent and use plastic scraper?
Thanks again

 

Yeah I have stripped lines with a open ended wrench. It's easy to do if the line is a little stubborn, do yourself a favor and get some line wrenches. The gaskets should kinda fall off since it is a air only seal to get the the injectors. If your having trouble with gasket removal i have always carefully used a razor blade and they come right of.

 

0k, got a chance to get injectors installed finally and almost ready for a pressure test for leaks before reassembling everything...got the 4 bolts on fuel rail snugged down but are injectors supposed to be loose enough to twist in seats? I have looked around but can't find torque specs on 4 fuel rail bolts and runners bolts. Anyone know about this? Seem to remember the number 25 but want to be sure i don't strip threads now when so close to finishing.... thanks again guys!

 

8mm bolts into aluminum should be about 18ft lbs. The injectors will rotate in their bungs. I assume you lubed the o-rings with vasoline or equivilent to help them go in smoothly without cutting.

 

I just had an experience with my 1990 iroc 3.7 shutting down and loosing the pulse to all the injectors after the car ran for a few min. I replaced the ecm, the pickup coil , checked all the grounds to the ecm, replaced the ignition module and finally... After scratching my head for two weeks decided to unplug the two injectors that would not ohm out and the car started and ran without shutting off . Of course i had a miss in it am changing all the injectors. Apparently if you have any bad injectors it will send a signal to the ecm shutting the pulse off to all of them pretty dam strange if you ask me but it worked.

 

3.7? if a injector is shorted the injector driver will not pulse.

 

YOURE AWESOME!!!

I ohmed out my injectors, found two that were very low. Car would not start, changed cap/button, etc. plenty of spark, spray gas in intake and she'd tumble over for a few seconds. knew it wasnt spark, and after she sat for a few hours (injector bleed down in to intake) it'd fire over for a few seconds and immediately sputter off. Spent days stressing about what to check next. Found this thread...

unplugged lowest reading injectors and car starts now--6.6Ohms times 2. One was shorting out the rest of the bank or the whole driver, not sure which, dont care. She's firing on 7 cylinders now!!

just wanted to add some followup. I'll be rebuilding sooner than later, so I may just park it for a while knowing I can get it up and running to move her. cant wait to get it built

 

hey guys,

new to the site here... but has anyone figured out what is wrong with these cars?? Or are there hundreds of these things sitting in garages just turning over and not starting??

Here's my story... 89 iroc with the tpi vin F. no codes. car was running and just died. seemed like the icm was failing as it got warm. took it out, had it tested and it failed when it got hot. replaced.

found cap and rotor to be not as good so i replaced them along with the ign. coil. lots of spark but still wont run. just turns over and randomly backfires.

as you've probably all heard this before, the car has proper fuel pressure at the rail. hooked up a noid light to both banks. light was very dim and flashing rapidly. a toyota tech said that gm used rapid fire injectors and that was normal???

he performed some ohms tests and hooked up his snap on scantool, no codes, no open flood mode. reccomended a new ecm after reading the FSM. said all symptoms point to ECM. replaced. same problem.

read that a bad injector can take out the driver in the ecm. new ecm was installed with old stock rochester injectors that i later discovered were faulty(2 per bank) replaced with ford equivilant( all were within ohm specs) still turns over, no start just backfires.

all fuses are ok... VATS, both injector fuses, ecm fuse, and even some random 4amp glass i found by the heater motor... Vats seems to be ok. fuse out, key just turns forward. no clicks from starter ar buzz from pump.

could i have dicked the ECM by trying to start it with bad injectors?? or does the driver just not close the circuit...

car has been down all summer so any advice will be greatly appreciated. also in the southern ontario region if any locals check here

Cheers guys!!

 

Has anyone out there used a Painless 65104 fuel injection harness that has the Delphi marine ECM. Everything is fine except the injectors don't fire. I have 12V to both sides of the injector connectors. This is a 1989 350 TPI engine in a '55 Studebaker coupe so everything is new. Ididit steering column with no VATS. I have checked grounds and everything that I can think of. Thanks for any help.

 

Are you using a stock 89 chip?
The stock chip has vats enabled, the car will never start with that chip.

 

This is a delphi mefi series ecm not gm 165. You may want to go over you distributor icm connection, ecm power and grounds.

http://www.michiganmotorz.com/codema...er-p-2459.html

 

Hi again..jZ got back in town and ready to finish getting bird started. I finished getting injectors installed and bolts tightened. No leaks, but no start either..not even a p0p! Its looking like maybe it is the ECM drivers that got blown with my many attemts to start before new injectors. When backprobing ECM power inputs, voltage is 12.60, but then drops to 10.00 V. when cranking. Is this normal or enough power for ECM? Should i try a dedicated 12 volt power supply to ECM or jZ order one? And when i do, is driver circuit in ECM board or do i need to order new prom for it? Alot of questions, i know...but i've been gone a long time and would like to drive my bird before cold hits. Thanks brother bird lovers.

 

0K, jZ want to follow up on this...Shes alive now, jZ need to do final timing.
This all started with a no start unless starting fuid was used...then replaced injectors, pickup coil..but still only a pulse to injectors when touching purple wire to dist. So i finally noticed corrosion on the old icm i used, cleaned it and she starts. Took alot of testing of wires and components to get to this point, so i'll jZ say to the others having troubles out there...don't give up...jZ have to keep looking at things until you see that breakthrough moment...jZ need to give timing a little bump and put computer back in place and give her a test drive.
Good luck and never give up...solution might be found sooner than you think. (Tell this to your wife or GF when they want you to part it out) Hehehe Good Luck!

 

so post #8 helped ?

 

Msg # 8 went another user, so maybe i didn't pay attention to it...til recently...i reread posts and looked at icm connectors after a strange reading on meter...i was going in too many directions at once a few months ago trying cover all areas at once...not good to do that...many thanks to Tunedperformanc for giving me advice on this, cuz it could have been any number of things. One thing he taught me about troubleshooting is to be more methodical..and check well 1 section at a time. We are all lucky at this site to have guys like him.