Cranks but no start in mornings

TMEADOWS110

MEMBER
2003 PONTIAC GRAND AM
3.4L
V6
2WD
AUTOMATIC
190,000 MILES

The car was fine, no starting issues, then one day wouldn't start. Unplugged the battery for 30 minutes to reset computer and the re-plugged and it started right up. Happened again a few days later this time unplug hing the battery didn't work, the battery ended up dying and got replaced but still no starts in the mornings. Yesterday car wouldn't start, reset battery and still wouldst. I left for work came back that evening and the car started right up like it never had a problem. I think it is cold weather but not sure. Walk me through this please.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,779 POSTS

Hi,

Are temperatures much colder in the morning? I don't know where you are located. Based on what you described, I question a couple things. First, can you tell if the fuel pump is actuating when you first turn the key from off to on? There could be a fuel pressure related issue.

Next, there is an engine coolant temp sensor (ECT) that tells the computer the temp. Based on that info, the computer determines how rich or lean to make the air / fuel mixture. If that is way off, it could prevent it from starting.

The easiest way to test the sensor is with a live data scanner. Basically, you check to see what the ECT is indicating the temperature to be. It should be close to the outside temp if the engine is cold.

Here is a link that reviews the most common cause of a crank no start condition. Take a look through it and let me know if anything there is helpful.

https://www.2carpros.com/articles/car-cranks-but-wont-start

If you decide to test fuel pressure when it won't start, here is a link that explains how. You will need a fuel pressure gauge.

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

One other thing that could be related is if there is no ignition spark to the plugs. Honestly, chances are this isn't the cause, but here is a link that explains how to test for spark. Do this last if fuel pressure is good and the ECT checks good.

https://www.2carpros.com/articles/how-to-test-an-ignition-system

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I realize most people don't own the tools I mentioned, but often times, a parts store will lend them to you with hopes of selling you a new part.

One last thing. Here are a few links that you may find helpful when testing for spark:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

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

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Let me know what you find. If you have other questions or need help, feel free to let me know.

Take care,

Joe