2001Buick wont start

My father has a 2001 Buick La Sabge anmd last spring it would start hard when it was cold it warmed up and stoped so My father thought it was the battery so he replaced the Battery well this fall when it got cold it started doing it aggain but now it ran rough untill it was warm then justr recently it turned into everytime u would stop it would stall out I took the airfilter out and put a new one in and it seemed to run good for a few days then it got even werse it has gotten to the point that my father could only go 15 and had the peddal to the floor and it was backfireing only the Misfire fuel and comprehensive componint monitors are in a ready status with no DTC's I will pull spark plug tomorrow and let you know whatI find any advice will be helpfull

When the vehicle won't start, check fuel pressure, spark, and injector pulse...

Check the fuel pressure regulator vac line for fuel....

Try starting with the MAF disconnected...

I forgot to mention its not even engaging the starter a friend of mine suggested it jumped time dose anyone think he is correct and I did not get a chance to pull a spark plug

I forgot to mention its not even engaging the starter a friend of mine suggested it jumped time dose anyone think he is correct and I did not get a chance to pull a spark plug

Does the starter turn over the engine?

Does the engine start running?

no all it dose is make a click kinda like when the starter goes but it is a little different

I guess we got the rest of the story....

Check the battery connections.......if ok(clean and tight, replace bolts if necessary), put a voltmeter across the battery(nothing on)...should read 12.6 volts......what do you read when key is in the crank position?

Should be at least 10.0 volts.....If over 10 volts, bad starter/connections at starter.....less than that, battery is dead....try jumping the battery or recharge it....

If it starts, check output of alternator with voltmeter when engine is warm...rev to 2000 rpms...should be over 13 volts....

If it is, check for a parasitic draw........

no all it dose is make a click kinda like when the starter goes but it is a little different

Check the ground connection at the floor pan. Remove and clean if necessary to be sure there a clean bright metal connection.

Have someone tap on the starter with a hammer, lightly, while the key is turned to crank. It could be the starter...

a good troubleshooting for the connections and the weak battery suggested in the previous post, is just connect a jumper cable from another good battery in a running car. If that provides the right power to start, then trouble shooting backwards toward the battery.

checked with my father its no starter that was just replaced in the past 3 months and Battery is good cause it was just replaced only other thing it could be is alternator how would I check that

The alternator is not used to crank a vehicle....

checked with my father its no starter that was just replaced in the past 3 months

If you mean the starter was just replaced, doesn't mean that it can't be bad.....if the battery is good, and you have power to the "S" terminal of the starter with the key in the "crank" position, the starter is bad.....if you DON'T have power in the crank position, does the SECURITY light go out after 5 seconds when the key is just turned to the "run" position?

Battery is good cause it was just replaced

No, the battery could be dead if the vehicle has a parasitic draw OR if the alternmator was not charging the vehicle.....but if it wasn't charging, the RED BATTERY indicator would have been on while he was driving it....

Was a voltmenter put on the battery and tested like I asked? You can't check if the alternator is charging, unless the vehicle is running.....was the battery checked? Were the cable connections checked? Did you try to jump start the vehicle?