Buick Repair Questions? Ask a Mechanic for Answers ASAP
I have been a professional master mechanic for over 35 years and am happy to help you with this.
Thanks for the detailed info!
When its in a no-start condition, have you tried spraying some carb cleaner into the air intake hose? Spraying it towards the engine and see if it starts for a second or two?
This will at least confirm that it is a fuel issue.
That test will tell us if it is a fuel or a spark issue. it will be one or the other.
Being that you have replaced the fuel pump we can pretty much assume its ok.
If it doesnt react to the carb cleaner, then its an ignition issue because it isnt getting spark to the plugs.
There are a few different parts that can cause this but at least you can narrow it down.
If it is missing spark to the plugs, the most common reason for that is the ignition control module.