Engine will crank but no start?

Tiny
JESS_SILVERADO
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 403,000 MILES
I have rebuilt the engine for this 5.3
The short block has all new everything except for the block and rods.
Engine will crank, but only for 3 seconds. No more, no less. Every time.
Will not run at all with starting fluid. All fuses and relays have been checked and are working. No codes are present or pending. I only have not been able to verify if there is spark.
Is there some insight to this 3 second cranking thing? Security issue? Or something else?
Sunday, April 23rd, 2023 AT 3:37 PM

10 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,724 POSTS
Hi,

If you tried starting fluid and there is no change, either there is no spark, or the timing is off or there is low compression.

First, let's confirm there is spark.

Here is a link explaining how it's done:

https://www.2carpros.com/articles/how-to-check-for-ignition-spark

Also, if you have a live data scan tool, check to see if there is an RPM signal when cranking.

Let me know what you find.

Joe
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Sunday, April 23rd, 2023 AT 9:48 PM
Tiny
JESS_SILVERADO
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  • 7 POSTS
Okay, I attempted to verify a spark at the boot yesterday but did not use that method and was unsuccessful. I will use that method and see what I get. If that doesn’t provide spark, I am going to try grounding the bank at the main harness connection and see what that gives me. I will let you know later on today.

Also, just to note, all the sensors and spark plugs are brand new. Coil packs and wires are not new, but were working just fine when I parked the truck to start the project.
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Monday, April 24th, 2023 AT 9:38 AM
Tiny
JESS_SILVERADO
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  • 7 POSTS
So, I have no spark. There is power at the main coil harness. Not at the individual coil harness. Now what?
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Monday, April 24th, 2023 AT 3:51 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,724 POSTS
Hi,

Have you checked both injector fuses in the under-hood fuse box? They are what power the coils via a pink wire.

Also, when you checked for power at the injectors, how was it done? Did you use a test lamp, multimeter, Noid light? I ask because if it was a Noid light, there may not be a ground path to complete the circuit.

There is a common ground on the left side front/lower part of the engine for all coils. They are known to fail. The connector basically corrodes and falls apart. Check that for me as well.

Let me know.

Joe

See pic below.
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Monday, April 24th, 2023 AT 7:06 PM
Tiny
JESS_SILVERADO
  • MEMBER
  • 7 POSTS
I have checked both injector fuses and all others including relays in engine bay box and in-cab inside driver door. I used a multimeter for this.

I have checked that small ground at the front lower left block and have inspected, rewrapped it, and is correctly grounded. Aside from the islet and immediately following islet I don’t know. It looked good when I rewrapped though.

I will trace the pink wire best I can and also pull up the engine bay fuse box and be sure there is no damage to wires there, but everything looks and feels good. Not too much brittle going on.

I will let you know, thanks
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Monday, April 24th, 2023 AT 8:11 PM
Tiny
JACOBANDNICKOLAS
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The pink wire is spliced in several places. If any of the splices fail, you will lose power.

Let me know what you find.

Joe
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Tuesday, April 25th, 2023 AT 6:11 PM
Tiny
JESS_SILVERADO
  • MEMBER
  • 7 POSTS
Hi, so I checked that there was fuel pressure at the rails, which there is. I did a little bit of wire tracing but came up with nothing remarkable. Still no spark. So, I decided to drag it over to a local Diag shop since I, nor anyone else I’ve had come help me can figure it out. I will let you know what the Diag finds though...
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Wednesday, April 26th, 2023 AT 9:50 AM
Tiny
JACOBANDNICKOLAS
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Hi,

Sounds good. Let me know what you find out. I'm interested in knowing. I have a feeling it is one of the splices, but anything is possible.

Take care,

Joe
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Wednesday, April 26th, 2023 AT 8:02 PM
Tiny
JESS_SILVERADO
  • MEMBER
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Hey Joe, so sorry for the delayed response. It’s been crazy busy for me. Anyway, the problem apparently was dirty connectors if you can even believe that. The diagnostic shop had it for about a week and a half, went through everything, chased wires, and had no luck. As a last-ditch effort, they cleaned everything and that got it running. They replaced a bad Oil Pressure Sensor pigtail and completed the Crank Position Sensor relearn procedure. It has some intermittent starting issues now but always fires up on the second key turn. I’m thinking it will just need a tune. Runs like a champ though and has had about 600 miles put on it so far. Thanks for all your help.
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Friday, May 26th, 2023 AT 9:18 PM
Tiny
JACOBANDNICKOLAS
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Hi

Great to hear from you and thanks for the update. As far as a faulty connection is concerned, that isn't that out of the ordinary. I'm not sure what was the exact repair, but it's working and that's what is important.

Take care of yourself and feel free to come back anytime in the future. You are always welcome.

Joe
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Friday, May 26th, 2023 AT 9:55 PM

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