I'll attempt to make this as quick as possible.

Last week I bought a 99 MC LE for fairly cheap. The owner said I would just need a new battery, so I went and picked one up from Walmart before picking it up.
We changed out the battery and it ran very smooth while I drove to the store and around town for an hour or so. I got back home and parked it for 4-5 hours and went to go to a friends house but it died right after start up. The lights were flickering and dimming including the headlights & tail lights. If I keep it at around 1500 Rpm it'll stay running, but will die when it hits 1000 Rpm. I checked the connections to the battery and they were tight with no wiggle, and the wires to the starter were tight and clean. The battery hasn't fully died though considering it's been a week from today and it'll still crank over but won't start. I know the MAF sensor wouldn't cause it to flicker but I disconnected it anyways and still dies out. I do recall the seller saying something was pulling power so he had to unhook the radio, which would imply a bad BCM by chance? Quite a few warning lights pop on including "volts" "change oil soon" "Oil" and "Engine check light". It just seems odd that the battery has yet to fully die, which would indicate that the BCM isn't bad. I'm just really confused on what the issue could be. I'm hoping to get a jump or tow to get it to a auto part store for free testing, however I feel as though someone may know a trick or something. Any help would be greatly appreciated.

 

Better to get it right than to be quick sometimes.

The new battery should test out at about 12.1 volts just sitting there any less than that it may not start when fully charged it from the alternator it would test at 12.7 to almost 14.7. Seems crazy but I can verify that.
Most of the time it is in the connections that make this car not start.
Double check and clean the connections. The ground cable could be cracked as well. It could be that the starter is planning on going bad too.


The photo I am attaching shows the inside of the engine bay and if the Vacuum lines are goofy leaking this causes all kinds of issues. Where the Red arrow is shows a big Vacuum line connection. If that comes loose or falls out the thing won't start or if it does you will need to feather the gas to keep it running.

Another thing to do is change the fuel filter located under the passenger side seat on the underside of the car (beer can looking thing with to lines into it, do not use a Crescent wrench to loosen the lines. When you get ready to start it if you listen when you turn the key to on, you will hear the fuel pump come alive a little buzzy groan sound, (now you know that is working).


Also put in a new Air filter it will need to breathe.


I purchased a 96 Monte for my son in high school and these things all came along during his driving time. I had to rescue his car a lot.
Okay that's about all I can think of right now, keep us informed on you progress.

 

Thank you very much man! I'll go do this right now and update you asap!

 

I did a little digging around and everything looked great. I checked for vacuum leaks and there wasn't any. Removed all ground connections to the starter grounds. Fuel pump starts right up! However I decided to take a look at the fuse panel which should've been obvious to do. This is what I find with almost every other fuse in it. This is the starter relay.

 

That one if it was bad the curved flat wire would be broken, get your fuses from the GM dealer or Napa some of the cheaper ones can malfunction and cause a fire. This car has 2 fuse panels one is under the hood and the other by the passenger side glove box on the end.

 

True. Decided to get the alternator tested anyways and it came back perfect. Cleaned out the throttle body and sprayed more carb cleaner on the and no air was leaking. Bought a new air filter as well and installed it. We also tried to jump it before going to Advanced to have them test everything, but it just wouldn't stay running. It's just so odd that it ran perfect and the battery is at 12.1 and the alt tested at 12.7-12.8. All connections are solid and tight. Could it be within the harnesses somewhere? I'm for sure not an expert on vehicles, but it sure is baffling.

 

So I still think its a Vacuum leak it would make any noise.
I am assuming it will crank but won't stay running once it starts. If this is the case there could still be a vac line open. Or that fuel filter is plugged up and it aint getting the fuel.

 

No noise coming from it whatsoever. Sprayed every hose down and seen nothing or heard anything while my brother was looking as well. The vacuum hoses look brand new compared to all other hoses. I know that never really means anything, but we looked for at least 45 minutes or so for any leak at all, even a pinhole leak, but never could see a bubble or anything. Is there a better way to check other than listening or spraying cleaner on it? Sorry if this is a hassle at all man. I really do appreciate all the help!

 

Wow, i'm a complete dippy. I replaced the *air filter* when you clearly said the fuel filter on the pass. side. I'm going to go out right now and give it a peek. Jeez, I am sorry about that.

 

Normally when you find a vac leak it really makes no noise and it won't bubble usually because it is inhaling and not exhaling.