Stalling problem and battery light

10

Asked by Mason Jun 11, 2022 at 05:57 PM about the 2003 Mercury Grand Marquis GS Convenience

Question type: Maintenance & Repair

Hello I have 2003 grand marquis with 148k it was
driving fine then out of no where my battery light came  
on I had the battery replaced I had the alternator check
the first thing we did was unhook the battery terminals
on the car and it continued  to run with the battery
unhooked I had the battery replaced I had the ground
wires replaced battery still drops and the battery light
is still on the  alternator make a nosie as if it's charging
but then stops its like humming nosie but the car has
never died or stopped on me and I do not have starting
issues  now The car is starting to stall it showed a
check engine light for a  miss fire had the plugs and
coils replaced light eliminated it drives and idles
smooths but It still stalls every now and then just not
as much and when hard accelerating it doesn't do what
it supposed to do but in park it revs great
Tested  the alternator 3 times and it failed one  out of
the thee times
My question is can a bad alternator
Cause stalling or low fuel pressure Issue..and if not is
there anything you guys can recommend me check?

3 Answers

1,950

You need to find a friend that has a modus ultra and see what the alt is doing in real time, the charge circuit is controlled by the pcm, to charge full on start up, and surface charge to maintain amps under full charge conditions, inspect inside of connector (plastic) for corrosion or melting, also due to wire placement break inside the insulation and work intermittently until engine bay heats up and softens insulation. Hope that helps.

1 people found this helpful.
158,195

You got lucky!! You should never EVER disconnect the battery with the engine running!! Doing so creates a power surge that can fry the PCM, among other things!! Don't do that again!! When the "battery" light comes on it's telling you the alternator is not charging the battery. Not that the battery is dead or bad. Replace the alternator. It may be drying and testing ok but in the "real world", under the hood, it may not be performing as it should. With electrical problems things may work perfectly in certain conditions, like when their cold, but break down when they get hot. Ignition coils, for example, are notorious for that. Also check your serpentine belt. Make sure it's not slipping and the tensioner is not at the end of its travel indicating that the belt is worn out. Hope that helps! Jim

10

I've changed the tensioner the belt was fine we also just changed the alternator nothing is changing makes me belive there was nothing ever wrong with my battery are alternator it has to be something else ...I already had the ground wires changed

1 people found this helpful.

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