2005 Grand Prix 3800 series 3 127k miles

My wife was driving and lost massive power and could only drive 30 mph. This happened 5 miles after filling up with gas. She parked the car and it didn’t restart. After doing to basic testing I noticed my fuel pressure was low. Replaced fuel filter and fuel pump. Car didn’t start but the battery was slightly low so I threw it on the charger. It started up and I drove it around for 15 minutes and parked it and then it wouldn’t restart. It turns over but won’t fire. While connected to a charger left on over night it will fire and occasionally start but dies as soon as you give it throttle. I have scanned the car and no codes come up. After talking to people and researching common problems I have replaced a few things,

Plugs and wires
Crank sensor
Cam sensor
Why would it start after sitting on a charger for a while?
Any ideas what to test/look for?

Double check battery -> Alternator fuse -> alternator wiring -> alternator.

chances are the battery has shit out. when they are dieing you can sometimes get them to start once after a charge, but the damage is already done and wont hold a charge right. im sure if you had the tester you could see the CCA is way off from where it should be at this point.

a dieing battery on a fuel injected car could explain all the other issues. low voltage can wreak havoc on all the electronics that control the motor.

This post was edited by night_throne on Aug 4 2019 04:46pm

Did you check fuel pressure after replacing the pump and filter? If this started after filling the tank I would have a closer look at the tank itself (debris causing a clog) or if she overfilled(s) could be an issue with your venting system. Also the alternator and battery, like the guy above stated, low voltage will give all sorts of drivability and accessory equipment problems.

i would start with having the battery tested and if it tests bad obviously get a new one. watch voltage if its not charging the battery i would go for the alternator next. if you are charging it and it starts but wont hardly run before it dies again it most likely is the alternator not charging the battery up like it should

sounds like alternator

fuel pump is failing/ clogged fuel filter

This post was edited by BBQSeX on Aug 22 2019 09:47pm

Could be a case of clogged CAT converter also.

I'd start with distributer/igniter/w.e it has

Even if you're seeing spark off the boots, might be too lousy