After replacing the alternator, the engine turns over slowly and backfires and will not fire?

2007 CADILLAC STS

181,000 MILES • 3.6L • V6 • 2WD • AUTOMATIC

TRAVON SPEED

MEMBER
1 POST

Got into my car this afternoon and started my car only to find an error message stating that there is a problem with my charging system. So, I drove to Orielly auto and shut the car off and asked if they could test my alternator and they did. It was bad, so I shut the car off and got the price only when I came out of the store my car gave me a click and would not even try to start. So, I bought an alternator and while I was putting it in, I had jumper cables from my friend's car hooked to my battery and when I was done the car turns over slowly and backfires and will not necessarily fire. I'm not sure what's going on with it. I know it should be getting fuel because I hooked up the fuel pump to direct power so I know that can't be my issue and I'm very lost now and out of ideas. Can anyone please help me?

Nov 22, 2022 at 8:46 PM

JACOBANDNICKOLAS

✓ASE Certified Mechanic
110,194 POSTS

Hi,

This sounds like a voltage issue. Nothing would have changed to cause a backfire by replacing the alternator. Take a look through this link:

https://www.2carpros.com/articles/engine-backfires-while-running

There is a chance if your battery is low enough, jump-starting won't work. What is the voltage at your battery when not connected to jumpers? If you have a helper turn the key to the start position, what does the voltage drop to?

Let me know.

Joe

Nov 24, 2022 at 7:32 PM

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