Crank no start? CRANK NO START I HAVE 12V TO CRANK AND CAM SENSOR?

KEN L

MASTER CERTIFIED MECHANIC
47,536 POSTS

Yes, I will assign a new mechanic to your problem.

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Thursday, January 26th, 2023 AT 12:01 PM (Merged)

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

I read through the different posts above. Before I can get started, I need some information that was a bit confusing above.

First, is this a 2500, 3500?

The one thing I feel confident about is there is no injector pulse/ground being provided by the PCM. You mentioned it didn't have spark and then it did. Does it have spark at this point?

Do you have a live data scan tool? If so, is there an RPM signal when the engine is cranking? This is important because if there is no ignition reference, the PCM will shut down the injectors to prevent flooding or backfiring.

Let me know. Additionally, I just want to reconfirm that the crankshaft and camshaft sensors have been checked and are working properly.

Let me know.

Joe

Note: Although the PCM worked before being parked, it isn't uncommon for them to take on moisture and fail internally. I have a feeling that is the issue. If you have no ground path being provided to the injector but everything else checks good, the PCM is the most likely cause.

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Thursday, January 26th, 2023 AT 12:01 PM (Merged)

LOUD_8.1VORTEC

MEMBER
20 POSTS

I always had spark never lack of it and I don’t have a live data scanner, but I get 5v signal form 5v 0v 5v 0v like it should have to from crank cam sensor while cranking. The ground are perfect, all checked and tested, no resistance in it. For the PCM I have another grey truck next to it sit more time than the 8.1. In more this grey truck has 350,000km on it.

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Thursday, January 26th, 2023 AT 12:01 PM (Merged)

LOUD_8.1VORTEC

MEMBER
20 POSTS

I’m not a perfect mechanic because I don’t have the magic Snap-On scanner tool who did all nowadays on cars, but I’m not dump. I’ve 5 of them model of truck Silverado Sierra similar year 99-06 I disassembled and assemble all of them in piece so I know of what I talk 2500 and 3500 in my case it's not related
so resume.
62 psi of fuel the pressure drop in about 6hour so it’s not an weak fuel pump,
spark constantly so it’s not coil, wire or spark plug,
I had 5v signal from crank and cam sensor while cranking
No injector fuse blown cause ALL fuse are new and good
No ground injector pulse no resistance in wire harness all checked
All ground are clean and tight
I know it’s not the right BCM cause it’s a project truck and long story but he already have started with it so it’s pass lock security cause no light on and the truck never start
The truck start immediately when I poor some fuel or quick start in the intake and shut up right after I stop to putting fuel.
And a PCM at 700$ programmed I don't think so.

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Thursday, January 26th, 2023 AT 12:01 PM (Merged)

LOUD_8.1VORTEC

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20 POSTS

I wanted response soon as possible.

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Thursday, January 26th, 2023 AT 12:01 PM (Merged)

KEN L

MASTER CERTIFIED MECHANIC
47,536 POSTS

Is the fuel in the tank new? You could have bad gas.

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Thursday, January 26th, 2023 AT 12:03 PM

LOUD_8.1VORTEC

MEMBER
20 POSTS
2003 CHEVROLET SILVERADO
8.1L
V8
4WD
AUTOMATIC
155,000 MILES

Good morning,

I have 62 PSI of fuel pressure and I have sparks and also a good compression 190 PSI the only one is that I have pulses of only 6 volts at injectors and sometimes nothing without resistance in the wires between injectors and PCM. The complete beam is okay, no resistance. All truck fuses and relays are okay. The crank and cam sensor are new. The truck worked for a few kilometers without problem. I’ve already changed the BCM, and I’ve replenished the procedure for the tanks (passes the lock), etc. And I didn’t have a security light, but I suspect it’s because a similar problem happened to me by changing the BCM the more I scanned it and there’s a no-communication code between BCM and i/p and PCM. Yet I was able to make it work despite that last fall.

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Sunday, January 29th, 2023 AT 6:42 PM (Merged)