No Pulse to injectors

Tiny
BBOYETT86
  • MEMBER
  • 1991 CHEVROLET SILVERADO
  • 197,000 MILES
Chevrolet k1500 getting spark to all plugs, gas to TBI, continuity from ECM to injectors, but no pulse to injectors. Please help! Every possible part I could test passed just wondering if it is an ECM problem?
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Wednesday, January 25th, 2012 AT 7:32 AM

30 Replies

Tiny
RIVERMIKERAT
  • MEMBER
Hello,

This sounds like you have an ignition module or ECM that has gone partially out. Here is the engine and ECM wiring diagrams so you can see how the system works. Use this guide to check the connections/signals and then replace the ECM if everything checks out.

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (below). Please let us know what you find.
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Wednesday, January 25th, 2012 AT 7:59 AM
Tiny
BBOYETT86
  • MEMBER
Checked the fuel relays all good. So I replaced the ignition module and pick up coil and the truck fired right up, good call! I love this site, thanks again.
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Wednesday, January 25th, 2012 AT 8:47 PM
Tiny
RIVERMIKERAT
  • MEMBER
Good to hear, please use 2CarPros anytime we are here to help.

Cheers
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Thursday, January 26th, 2012 AT 4:04 AM
Tiny
LARRAN EPPARD
  • MEMBER
  • 1990 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 65,000 MILES
I am working on a C 1500 pickup with a 5.7 engine. With a noid tester on the TBI lead I get no pulse. I have tried disconnecting all sensors and have even replaced ECM. I have voltage on one side of injectors, but the ECM will not provide ground. I have tested the ECM for power and ground as best I can and all seems good. Engine will start if you pour gas in throttle body but will only run until gas in intake is gone. New ECM did not come with prom chips not sure if this may be my problem. Also, not sure about leads from distributor is this where the ECM sees that the engine is turning? This model does not have a crank sensor and I cannot find a parts listing for a cam sensor. Any help would be greatly appreciated.
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Wednesday, September 5th, 2018 AT 10:40 AM (Merged)
Tiny
LARRAN EPPARD
  • MEMBER
Rasmataz,
Thanks for the reply. This was where I was going next but I was not sure if the ECM got a signal from the distributor. Pulled cap and found several problems in distributor. Replaced distributor and problem is solved. I can see now that the older engines got their reference from the ignition module. Is this still the way the ECM gets reference or is that the job of the crank sensor now?
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Wednesday, September 5th, 2018 AT 10:40 AM (Merged)
Tiny
RIVERMIKERAT
  • MEMBER
That depends on the car maker. Thanks for letting us know your issue is resolved.
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Wednesday, September 5th, 2018 AT 10:40 AM (Merged)
Tiny
TOPFUEL
  • MEMBER
  • 1993 CHEVROLET SILVERADO
Electrical problem V8 Two Wheel Drive Automatic 216k miles

Hi, yesterday my truck would not start. I am getting spark, but no fuel is spraying from the injectors. I removed the fuel line feeding the TBI to check and see if fuel was reaching it, and it is. Not a lot of pressure but it is getting fuel. The TBI is a brand new Holley 670cfm that was working flawlessly up until the no start. The engine has been rebuilt but no problems to speak of until this. Fuel pump is the original so maybe its time to be replaced? Checked the fuses I could find in my diagram and they are all good, wiring looks sound going to the TBI and injectors. Just don't know why the injectors aren't spraying any fuel after trying to start multiple times.

Thanks in advance!
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)
Tiny
RASMATAZ
  • MEMBER
What you need to do here is check the actual fuel pressure with a fuel pressure gauge designed for your fuel system

Here is a guide

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

if okay-check for power to the injector/s-got power still no pulses-could mean the computer ground drivers has gone bad

Here is a guide

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Check out the diagrams (Below)

Please let us know what happens.

Cheers
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)
Tiny
TOPFUEL
  • MEMBER
Checked fuel pressure to TBI, its sitting at 13 There is power going to the injectors, what else would cause this problem?


http://www.2carpros.com/forum/automotive_pictures/278243_IMG_0920_1.jpg



http://www.2carpros.com/forum/automotive_pictures/278243_IMG_0919_1.jpg

psi.
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)
Tiny
TOPFUEL
  • MEMBER
New thought, I recently had a car security system installed, could this have somehow caused a problem so suddenly a week after installation?
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)
Tiny
RASMATAZ
  • MEMBER
If it has to do w/the security system it won't last a week. Hook up a noid light to the injector and see what happens-if its not blinking its not pulsing could be the computer ground drivers -or the computer is missing an ignition reference signal from the cam/crankshaft sensors therefore not synchronizing the injectors.
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)
Tiny
EMD014
  • MEMBER
  • 2002 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 151,000 MILES
The fuel injectors on my 2002 chevy silverado HD only pulse once when I turn the engine over, no matter how long it turns over. Any idea what could cause this?
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)
Tiny
TOPFUEL
  • MEMBER
I don't have a noid light and its a too late to buy one today, but I threw a voltage meter on it and only saw constant current when the motor was cranking, no pulsing, then again the meter probably isn't fast enough to see the pulses. I guess i'll pick one up tomorrow. Thanks much for the help so far!
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)
Tiny
WRENCHTECH
  • MEMBER
Is your spark doing the same thing?
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)
Tiny
TOPFUEL
  • MEMBER
Hi again, tested injectors with a light and its not blinking at all on either injector. Checked for codes and its showing code 12 (No Problems detected). So I replaced the ECM and the truck started it was bad. Thanks for your help
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)
Tiny
EMD014
  • MEMBER
No, the spark is fine, it's a good strong spark too
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)
Tiny
BARFARMER
  • MEMBER
I have a 1993 Silverado that has don that more than once. In each case it was the Distributor. I bought a dist at Auto Zone with a lifetime warantee and they have to replace it about every 2Yr. You will think it is a fuel system problem but it is not. I have had this problem on another 1993 chevy custom with a 350 engine 2 times and my own at least 4 times hope this helps.
Keeps AAA in the Rollback business too ha ha
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)
Tiny
WRENCHTECH
  • MEMBER
Have you determined if it's the ground pulse dropping out or the power supply?
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)
Tiny
RASMATAZ
  • MEMBER
Test the pick-up coil in the distributor that's the one that synchronizes the injectors
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)
Tiny
EMD014
  • MEMBER
Hey, I apologize, my internet has been down, but I have been doing some more testing and realized that my spark plugs are doing the same thing, pulsing once, and then quitting, no matter how long I turn the engine over
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Saturday, April 13th, 2019 AT 6:34 PM (Merged)

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