No spark, no injector Pulse

TRYATES2001

MEMBER
2000 CHEVROLET 1500
4.8L
V8
2WD
AUTOMATIC
98,500 MILES

Stopped running while driving. Replaced cam and crank sensors, replaced battery, and checked for fuel delivery. Has good power and fuel but no spark what so ever or injector pulse, has power at the fuses while on run and crank position but no pulse at plug. Took it to a shop and they couldn't find the issue either, I have been dealing with this for 3 weeks now and still nothing. So i'm just looking for some answers or something that will help me out.

3 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Based on this, the thing that makes the most sense is a faulty PCM but we need to confirm it is getting the crank signal. Here are some guides that will help with this:

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

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

Below are the wiring diagrams for the crank sensor and injector. Let's make sure we are checking the injector as shown above for a pulse. If it is not pulsing then we need to make sure the PCM is getting the crank signal. It would be best to get a scope pattern but as long as we can confirm it is getting voltage on the CKP wire at the PCM. If it does then the PCM is getting the crank signal but not sending the pulse for the injectors or coils. This is what the PCM uses to determine injector pulse and to fire the coils.

I attached the process for replacing the PCM if this proves out.

Let us know what you find with this and we can go from there. Thanks

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Friday, February 26th, 2021 AT 6:00 PM

TRYATES2001

MEMBER
2 POSTS

So I did the test wrong for injector pulse, I did tested again using the link you attached above and my test light was flashing while it was being cranked indicating I have pulse. But I still have no spark on all coils. Still a crank no start with no spark.

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Tuesday, March 2nd, 2021 AT 4:20 PM

KASEKENNY

MECHANIC
18,907 POSTS

We can assume that the PCM is getting the crank signal since you replaced the sensor so that leaves wiring and the PCM. If you had an oscilloscope we could test that the PCM is getting a good signal but not many people have those.

This means if it were me, I would test the coils and make sure it is getting voltage on each of the wires. I suspect you will find the control circuits are not getting power. If that is the case then the ECM is the issue. If the ignition feed circuit has no power then you have a fuse issue but there are separate fuses for each bank of cylinders so it is unlikely that they are the issue.

Let me know what you find.

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