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Fuel Injectors not getting power

Tiny
HEARTSHAPEDNOOSE
  • MEMBER
  • 1984 CHEVROLET CORVETTE

Ok, my cousin just bought a 84 corvette with the 5.7L tbi crossfire injection. The person he bought the car from ran it out of gas and every since then the car would not start. They have changed the fuel pump, fuel filter, the relay and still nothing. Today we worked on the car for hours and found out we are getting gas to the throttle bodies but no fuel is coming out of the fuel injectors. We rented a fuel injector test kit (noid light) and found out that we are not getting pulse to the fuel injectors and both fuses to the injectors are good. Can anyone please tell me what could be causing this? My last thought is the ECM (computer) but he is hoping for something a little easier and cheaper. Please let me know if you could tell me what is going on here. Thanks.
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Monday, October 11th, 2010 AT 7:07 PM

12 Replies

Tiny
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If you have power to one of the injector harness and you hook up a noid lite and cranking engine over and the lite doesn't flash-The computer ground driver circuit is defective
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Monday, October 11th, 2010 AT 7:16 PM
Tiny
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There is no power that I know of at all to either injector. No pulse at all on either injector. The computer ground driver circuit, is that in the computer itself of is it something attatched to the computer? If that is defective does it mean I have to replace the whole computer?
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Tuesday, October 12th, 2010 AT 6:06 PM
Tiny
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Check the injector fuse if it has power-the fuses powers the red and white wire on the injector harness
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Tuesday, October 12th, 2010 AT 6:12 PM
Tiny
HEARTSHAPEDNOOSE
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Ok, I got a test light today and touched it to the fuses for the injectors and I was getting power to the fuses, so I then checked the red & white wires right before the clip on the injectors and was getting power there too, since I was getting power there too I decided to put a piece of wire in the clip and check for power and got power there as well. So this is where im confused, If I am getting power all the way through the wires and the clip how come the noid light did not pulse at all? Also, does anyone know of any diagram showing how to test the fuel pressure and charge the fuel pressure if you do not have enough? All I know at this moment is no fuel is coming through the injectors, but I do have power, but a noid light detects no pulses, so im confused, help me please.
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Wednesday, October 13th, 2010 AT 6:30 PM
Tiny
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The computer pulses the injector ground circuit-I've told you that earlier-the computer controls the ground if its working the noid lite will be flashing when you're cranking engine over-
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Wednesday, October 13th, 2010 AT 7:02 PM
Tiny
HEARTSHAPEDNOOSE
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Ok, sorry, I realized that after. So basically does it mean that I need to replace the ECM on the car or is there something else I can do?
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Wednesday, October 13th, 2010 AT 7:15 PM
Tiny
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Or the computer is not getting an ignition reference signals to synchronize the injectors-
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Wednesday, October 13th, 2010 AT 7:21 PM
Tiny
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How would I check that?
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Wednesday, October 13th, 2010 AT 7:26 PM
Tiny
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Could I test the injectors to see if they are clogged by running a ground wire directly to the ground on the injector clip?
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Thursday, October 14th, 2010 AT 2:49 PM
Tiny
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Ok, I know I havent got a response the past few days now. I found out that the injectors are not clogged and are in working order. Now I am planning on buying a new ECM (computer) for the car. I found a place selling them for $103 plus tax but I was told by a friend of mine that once I bought the computer I would have to have the place send out the computer to have it set for the car. Is that a true statement or will the computer be ready when I buy it? He told me that it costs about $60 to have them send out and set the computer for the particular car. Please just let me know if I need to do that or not. Thanks.
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Sunday, October 17th, 2010 AT 2:06 PM
Tiny
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With that vehicle you should be able to swap the Prom chip into the new ECM and it will work. This could very well be an issue with the ignition module/pick up coil as well. Have you checked for spark?

https://www.2carpros.com/articles/how-to-test-an-ignition-system
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Wednesday, June 26th, 2019 AT 1:26 PM
Tiny
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Turns out it was the ignition module and pickup coil in the distributor that were not sending signal to the ECM. Replaced them and she fired right up
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Tuesday, July 2nd, 2019 AT 6:19 PM

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