Will not start after driving it?

1998 CHEVROLET BLAZER
185,000 MILES • 4.3L • V6 • 2WD • AUTOMATIC
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BRIBRI4275
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  • 24 POSTS
I don't know why when i start my vehicle it runs fine but after driving it for a bit it won't start unless i wait for 15 to 20 minutes. I used an obd2 meter and it read that the MAP sensor had to be replaced. so i replaced it and it still does the same thing. Also, when i start the car sometimes it starts but the headlights are real dim for a couple of seconds then it like kicks in and they light up normal as if the battery has to warm up or something. Why is this happening? Thank you
Aug 11, 2021 at 7:06 AM
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KASEKENNY
  • Experienced Mechanic
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These issues could all be related but we need to start from the basics to find out what is going on.

First and foremost, what was the actual code that you have for the MAP sensor and can you check for codes again and see if that code is gone?

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

If that code is still there then replacing the MAP did not fix it. That could explain the hard starting or no start issue.

Here is a video that will help with this issue of not starting but let's get the code first:

https://youtu.be/dCjmRL3p4Cs

Also, we need to stop by a parts store and have the battery and alternator tested using these methods.

https://www.2carpros.com/articles/car-battery-load-test

https://www.2carpros.com/articles/how-to-check-a-car-alternator

If the battery is drained then it can cause these types of issues but we need to start with testing it.

If the battery is drained or the alternator is not charging properly then that will cause dim headlights until the system voltage is sufficient.

Please run through all this and let us know what you find and we can go from there.

Thanks
Aug 12, 2021 at 7:41 AM
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BRIBRI4275
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Hello there. I think i forgot to mention that it will start again after i sit and wait for the engine to cool down. Like maybe 20 minutes or so.
Aug 13, 2021 at 2:12 AM
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KASEKENNY
  • Experienced Mechanic
  • 18,907 POSTS
Okay, I understand. Is there any stalling when you drive? Meaning can you drive it as long as you want but just cannot shut it off? If you do it won't start until you let it cool down? Or will it shut off and then not restart?

Also when it will not restart, does it crank and not start or when you turn the key, does it not do anything?

The first thing that I am thinking if this just cranks and does not start if it is stalling then it could be a crank sensor.

If it is not stalling then this could just be a relay issue for the starter that is causing the starter to not come on.

When this happens, let's check voltage at the starter if it is not turning over and that will help us confirm this.

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

Below is the wiring diagram that will help with this as well.

Thanks
Aug 13, 2021 at 12:21 PM
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BRIBRI4275
  • MEMBER
  • 24 POSTS
I changed the crank sensor and it still does the same thing. I'm thinking maybe the fuel pressure regulator? because it seems like it wants to start but it just shuts off. Would I be wrong to think this way?
Aug 16, 2021 at 3:29 PM
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KASEKENNY
  • Experienced Mechanic
  • 18,907 POSTS
Very well could be. We are dealing with a spark or fuel issue so when this is happening we need to know what we are missing.

So when this shuts off and does not restart, you can test the fuel pressure then and make sure it is correct at that point.

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

Also, you can try starter fluid in the intake and see if this causes it to start.

This could also be an over fueling issue so if none of this works, try doing what is called a clear flood start. Hold your foot to the floor and start the engine. This will cut the feed to the injectors so they don't pulse while it is trying to start. If it starts then the engine is flooded and we have either a high fuel pressure issue or leaking injectors.
Aug 17, 2021 at 12:00 PM
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