Engine cranks but does not start?

2002 CHEVROLET BLAZER
212,000 MILES • 4.3L • V6 • 4WD • AUTOMATIC
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JUSTKEEPONTRUCKING
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About 6 months ago the truck broke down, stuttered then wouldn’t start back up, it would crank. Had a buddy tow me home and have done everything I can think of including taking it to two mechanics. Spider injector, ICM, fuel pump, distributor cap and rotor, battery, plugs have all been changed with more that I can’t remember, lots of money and time spent. I’ve checked spark and fuel pressure multiple times. After the shops don’t know what’s wrong with it, I’ve done everything I can think of, time to ask the internet.
Aug 3, 2023 at 8:40 PM
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STRAILER
  • Experienced Mechanic
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Yep, we can fix it, can you tell me if the engine will run on starting fluid? If not, I would check for spark and if there were none, I would replace the crankshaft angle sensor. Please go over this video:

https://youtu.be/baq_aEWNQ0Y

Here is a guide to help as well:

https://www.2carpros.com/articles/car-not-running-advanced

Also, the Spider injector and fuel pump, were they ACDelco units? We need to see if it is fuel or spark related. Here are the location and instructions on how to change out the crankshaft angle sensor with the relearn procedure. Check out the images (below). Please let us know how it goes.
Aug 4, 2023 at 5:57 AM
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JUSTKEEPONTRUCKING
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Checked and it has spark, all the replacement parts are ACDelco and seemed to be working fine when installed, I will replace my CAS again as I did it a few months ago. Could a bad vacuum system cause a no start on these engines? The line to the PCV valve is shredded and I’m wondering if it has too much back pressure somehow.
Aug 4, 2023 at 6:22 AM
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STRAILER
  • Experienced Mechanic
  • 55,249 POSTS
If the PCV hose has a leak that would be a large vacuum leak which can make the engine not start, I would repair the line to see what happens. Will the engine run on starting fluid Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.
Aug 5, 2023 at 2:59 AM
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JUSTKEEPONTRUCKING
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Hello, I have replaced my CPS again with a new shim, now it’s backfiring worse out the intake with flames, starting fluid did nothing if not make it worse. It’s not necessarily consistent and if I continue cranking, I’m sure to blow my plastic intake manifold. There are also still no codes, how would I go about checking the timing on this engine? This is the best I can do for a video, happy to hear back from you.
Aug 8, 2023 at 5:22 PM
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STRAILER
  • Experienced Mechanic
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Thanks for the video it helps. when you crank it over does it have consistent spark? It seems like it wants to run, when you turn the key on without cranking the engine over can you hear the fuel pump run for about 5 seconds?

Please check out this video:

https://youtu.be/baq_aEWNQ0Y


Please go over this guide and get back to us.

Aug 10, 2023 at 3:00 AM
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JUSTKEEPONTRUCKING
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I can take more but the noise is the same. Fuel pump primes, runs while cranking and runs a little when done cranking, I just replaced it about 4 days ago. I threw in a new IAC valve as someone told me it was the problem with no luck. Spark is consistent and strong with a new cap and rotor and plugs. I’m stumped.
Aug 10, 2023 at 5:19 AM
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STRAILER
  • Experienced Mechanic
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If you keep spraying starting fluid in the engine while cranking will the engine keep running? You might have a defective fuel pump. Also, I have seen the spider injector go out or the fuel pressure regulator leak internally, can you remove the spark plugs to see what they look like? Please upload images of the plugs so I can tell if the injector is bad if I can see the plugs.
Aug 11, 2023 at 2:51 AM
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JUSTKEEPONTRUCKING
  • MEMBER
  • 5 POSTS
Even with consistent spraying it just cranks, regulator is good no leak down on pressure test, it’s also the 3rd pump in 6 months because “they might be defective”. I can pull the plugs tonight and I’ll upload a video of them.
Aug 11, 2023 at 9:46 AM
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STRAILER
  • Experienced Mechanic
  • 55,249 POSTS
Sounds good, i think we might see them carbon fouled.
Aug 12, 2023 at 2:52 AM
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STRAILER
  • Experienced Mechanic
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anything?
May 6, 2024 at 5:16 AM
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