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kalamykid
kalamykid, Shop Owner/ Tech
Category: Chevy
Satisfied Customers: 4436
Experience:  I HAVE OWNED MY OWN SHOP FOR OVER THREE YEARS. I HAVE THE TOOLS AND SOFTWARE TO ANSWERE ALMOST ANY Q
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My '89 Celebrity has no pulse to the fuel injectors. It has

Customer Question

My '89 Celebrity has no pulse to the fuel injectors. It has fuel pressure and spark but no signal to the injectors.(checked with noid light) It will run if fuel is sprayed into the plenum. As mentioned by others in this forum...initially it would run fine when cold. It would then stall when hot and not run again until cold. However, now it will not run at all and there is no signal to the injectors. Can you offer suggestions?
JA: How many miles are on the vehicle? And when was it last serviced?
Customer: 114,000
JA: Are you fixing your Celebrity yourself? What have you tried so far?
Customer: checked the ignition module (spark is fine) Replaced the ECM. Removed the plenum and insulated every place where the wires looked chafed or rubbing
JA: Anything else you want the mechanic to know before I connect you?
Customer: thats all
Submitted: 1 month ago.
Category: Chevy
Expert:  kalamykid replied 1 month ago.

What size engine does your car have in it?

Customer: replied 1 month ago.
2.8 V-6
Expert:  kalamykid replied 1 month ago.

Do you have a digital volt meter and a test light so we can do some testing?

Customer: replied 1 month ago.
but please share your suggestions. Its raining at the moment and the car is not under cover.
Expert:  kalamykid replied 1 month ago.

The first thing I need to know is does the pink wire running to the injectors have battery voltage to it with the ignition switch in the run position?

Customer: replied 1 month ago.
Where am I checking this wire? Fuse box? I know there is currently no signal to the injectors.
Expert:  kalamykid replied 1 month ago.

You will need to check at the injectors please.

Customer: replied 1 month ago.
there should be power at the pink wire with the ignition 'on'....without cranking.....correct?
Expert:  kalamykid replied 1 month ago.

Correct.

Expert:  kalamykid replied 1 month ago.

The ecm sends the pulsing ground to the injectors to open them.

Customer: replied 1 month ago.
OK...I will check. But please allow me to carry on this chat later today or tomorrow. It is POURING down rain at the moment!! Sorry...how can I re-connect with you later?
Expert:  kalamykid replied 1 month ago.

That will be fine. All you have to do is come back to this chat screen and we can continue from here.

Customer: replied 1 month ago.
Great. I'll book mark it. It may be tomorrow before I can get back to you. Thanks!!
Expert:  kalamykid replied 1 month ago.

You are welcome. Chat with you when the rains stops.

Customer: replied 1 month ago.
Customer...are you there??
Expert:  kalamykid replied 1 month ago.

I am here. How can I help you?

Customer: replied 1 month ago.
Customer...are you there?? I DO have power at the fuel injectors!!
Customer: replied 1 month ago.
I have power at the fuel injectors. Bad ground somewhere??
Expert:  kalamykid replied 1 month ago.

If you have power to the injectors, then you need to take the ignition module to your local auto parts store and have them test it. The module tells the computer when to fire the injectors as well as tells the coil when to fire. The ignition side can still be good, but the fuel side may have gone out.

Customer: replied 1 month ago.
Hmmm...yes I already did that. The module tested good at Advance Auto Parts. I also the module from a running car and put it in this car....still nothing.
Customer: replied 1 month ago.
took the module that is
Customer: replied 1 month ago.
Any additional suggestions??
Customer: replied 1 month ago.
Hello???
Expert:  kalamykid replied 1 month ago.

Then it has to be the ecm B fuse is blown, or the injector drivers in the computer are burnt out.

Expert:  kalamykid replied 1 month ago.

Check the ecm B guse and see if it has 12 volts on both sides, if it does, you will have to replace the computer.

Expert:  kalamykid replied 1 month ago.

Sorry not the ecm B fuse, but the ecm fuse.

Customer: replied 1 month ago.
ECM has been replaced and I also pulled the ECM from a running vehicle and put it in this one. No go. As I mentioned before....when the problem first began, it would run when cold and then die when it got to operating temperature. Now it will not run at all. However, If it sits for weeks...it will start for a few seconds and then die. Its seems like the injectors have leaked down a few CCs of fuel over time...the motor burns that fuel and then dies. Thats what it appears to me. If I spray fuel or starter fluid in the plenum...it will run. So....are you referring to the ECM fuse in the fuse block under the dash....or is there another fuse inside the ECM??
Expert:  kalamykid replied 1 month ago.

If you can spray fuel into the intake and it will run, but the noid light does not flash when the engine is turned over, then the computer is not sending a ground to the injectors. The ecm fuse is in the fuse box. From all you have told me that it is doing, I would have to say the ignition module is bad. Check the metal connectors in the plug for the ignition module and see if one of them is damaged and not able to give you a good connection with the ignition module.

Customer: replied 1 month ago.
Will do
Expert:  kalamykid replied 1 month ago.

Let me know what you find.

Customer: replied 1 month ago.
Got it started but it only ran for a minute or so. Seems like the noid light was bright when it started...but the light got increasingly dim until it stalled. Wondering if there's a loose or corroded connection somewhere??
Expert:  kalamykid replied 1 month ago.

Did the noid light flash when it was running?

Customer: replied 1 month ago.
but the flashes got progressively dimmer until it stalled
Customer: replied 1 month ago.
seems like the signal was getting weaker as it ran
Expert:  kalamykid replied 1 month ago.

Did the pink wire lose voltage at the injector?

Customer: replied 1 month ago.
Didn't check voltage while it was running....just monitoring with the noid light.
Customer: replied 1 month ago.
If I can get it running again, I will try to monitor the voltage at the injectors. If voltage goes down while its running....what would that be indicating??
Expert:  kalamykid replied 1 month ago.

If you test the pink wire with the engine running and your black test lead on a good engine ground, then you are loosing voltage to the ecm B fuse.

Customer: replied 1 month ago.
What might be causing a gradual drop in voltage??
Expert:  kalamykid replied 1 month ago.

More then likely you are loosing the pulsing ground, not the positive power to the injectors.

Customer: replied 1 month ago.
it seems that way. This is driving me crazy. I have 42 PSI at the fuel rail...noid light is pulsing....and I have spark at the plugs. The only thing I can say is that the pulse at the noid light is not consistent. When its bright, the engine fires...when its dim...the engine stumbles and stalls.
Customer: replied 1 month ago.
voltage at the injectors seems steady
Customer: replied 1 month ago.
Where is the ground terminal location for the injectors ??
Expert:  kalamykid replied 1 month ago.

The ground comes from the computer. The computer gets its signal form the ignition module.

Customer: replied 1 month ago.
Do you know...physically....where it is all grounded??
Expert:  kalamykid replied 1 month ago.

The injector gets a pulsing ground for the computer itself.

Customer: replied 1 month ago.
HeyCustomer- Today I realized that there is a signal to my fuel injectors. However, the noid light seemed very dim. I was looking at the light in bright sun-light so I couldn't see it well. Once in awhile the engine will start when the signal is stronger. So, I took the liberty of checking the injector signal on my good running engine. (87 Celebrity with same motor) The noid light is VERY bright. So, this makes the mystery even stranger. It seems like the ground signal is not consistent. Sometimes good...sometimes weak. Do you still think the problem is at the ignition module??
Expert:  kalamykid replied 1 month ago.

The best way to see for sure would be to test the ground at the ecm plug itself so you know if the computer is sending a strong ground. To do this, run a wire from the batteries hot post to the ecm plug and connect one side of the noid light to it. then run a second wire from the void light to the Black plug at the ecm on pin C11. This will be a light blue wire with a white strip. Then turn the engine over and see if the noid light flashes brightly.

Customer: replied 1 month ago.
I'll give it a try and let you know what happens.
Expert:  kalamykid replied 1 month ago.

Thank you.

Customer: replied 1 month ago.
Do I have to use the noid light?? Or....if I run a hot wire from the battery to the ECM ...can I just connect the 12V wire to my 12V circuit tester light and then probe the wire at C11? O+ ------------------<circuit test light>---------->(C11 at ECM)
Expert:  kalamykid replied 1 month ago.

The noid light will be best.

Customer: replied 1 month ago.
ok
Expert:  kalamykid replied 1 month ago.

thank you.

Customer: replied 1 month ago.
OK...did as you suggested. Hot wire from battery to noid light near ecm. Other side of the noid light connected to C11 at ECM. As soon as the key is turned to 'run' position...noid light is on. Crank engine...no flashing....just solid light on. Turn key off...noid light flickers for a few seconds and then goes off. (there are 3 plugs on the ECM and there is only one light-blue wire with a white stripe)
Expert:  kalamykid replied 1 month ago.

That should not have happened. The light should have come on with the switch off, then gone out with the switch on, then flashed when you turned the engine over. Can you do the same test but this time on the light green wire in the black plug pin C 12.

Customer: replied 1 month ago.
Solid light green? Any stripe?
Expert:  kalamykid replied 1 month ago.

There are two wires that have a blue wire with a white strip, but the other wire is a dark blue, in the yellow connector pin F 9. So make sure you go to the black plug at the ecm. There are two bloack plugs, one is a 32 pin plug and the other is a 24 pin plug. The yellow plug is also a 32 pin plug.

Expert:  kalamykid replied 1 month ago.

Make sure you ate testing the light blue wire with a white strip, not the dark blue wire with a white strip. And yes you will be testing a light green wire with no strips on pin C 12.

Customer: replied 1 month ago.
I have the FSM...so I will try to confirm the correct wires. Meanwhile...I may have to go back at it tomorrow. Are you available tomorrow...or Monday thru Friday only??
Expert:  kalamykid replied 1 month ago.

I am online almost every day. I will be in and out tomorrow as I have an engine to build tomorrow for a dodge ram pu.

Customer: replied 1 month ago.
OK...I'll keep you posted with my progress and/or questions. Thanks.
Expert:  kalamykid replied 1 month ago.

Chat with you later.

Customer: replied 1 month ago.
Looking at the wiring diagram in the FSM. I see C11 & C12 for F/I. However, are they on the 24 pin black plug...or the 32 pin black plug? Also...the wiring diagram shows the F/I circuit being grounded thru the ECM to the chassis at G112. Do you know where this ground point is located on the chassis? I want to check it for rust/corrosion.
Expert:  kalamykid replied 1 month ago.

You are reading the wire diagram wrong. The injector wires run straight from the injectors to the ecm and they are on the 32 pin black plug. There is no direct ground to the injector pulse wires. G112 is a connector not a chassis ground.