Battery voltage increase when car is turned off

[UseDaGreyMatter]

Ok guys I need your help. they did not teach us this stuff in home ec. we have pretty much confirmed someone tampered with my 1990 lumina 2.5 ltr. they pulled a plug in the power steering wiring and bent a pin. We got that fixed. When the car is turned off the battery voltage is increasing. Was 13. something before we installed brand new battery. Then checked it again and it went up. Am figuring some wires are crossed some where but have no clue where to start looking.

[ktetch]

Ok, so when it's running, what's its voltage at the battery?

And then have someone turn it off when you're looking at it, what happens?

and 5 mins later, what's it at then?

[UseDaGreyMatter]

Originally Posted by ktetch

Ok, so when it's running, what's its voltage at the battery?

And then have someone turn it off when you're looking at it, what happens?

and 5 mins later, what's it at then?

That also is part of the problem we had the car up and running fine. basically replaced every thing in ignition system except computer. right before the plug thing happened it started acting like it needed a tune up and started running really rough again,. now we final got it to start but it dies after a couple of seconds. can have guys try to get a reading as they start it

[jeffcoslacker]

If the voltage is increasing after shut-off, the charging system is not working right, the battery is rebounding from being asked to run the car itself, rather than the alternator handling the load. It should show no less than 13.8v running, 14.0-14.5v would be preferable. When shut down it should drop and settle to around 12.8-13.0v if the battery is in good shape.

If you have under 13v running, and it comes UP when you shut it off, you are not charging, alternator or fusable link suspect.

[UseDaGreyMatter]

last night right before and immediately afterwards unhooking battery, it was showing 14.5 v
today after we unhooked it, it was showing 14. 13


Before we hooked the battery back up today it was showing 13.4
before and after we hooked up battery both readings were 13.85
turned ignition key on
we checked fuses, before we pulled fuses the volts read at at 13.85.


when we pulled these three fuses the volts went up to 13.99, then they dropped to 13.7v then went back up to 13.8 and held. Before fuse was reinstalled after installation volts read went to 13.99, dropped to 13.7 then went back to 13.8 and held.


1.when we pulled out the abs fuse , the primary fan shut off and the cars blower came on .

1. on primary fan fuse when we pulled it, the primary cooling fan shut off. the internal blower came on
2. When we pulled 30 amp fuse closet to fender. Primary cooling fan shut off and internal blower came on

1. when we pulled other fuses nothing happened.

is that normal?
When battery disconnected to day was reading 14.13 , read again about 5 minutes later and its reading and even 14.v




redid fuse check with key off


no changes in voltage when we repeated volt test on each fuse.



Taking alternator to oreillys tomorrow, looking up fusible links in chilton and haynes.
Does any one know if the 2.5 sedan and APV have same fusible link by battery that looks like a wire?

Thanks

Will post updates after we get test results.

[Schurkey]

Have you verified that the voltmeter you're using is accurate?

14+ volts out of a "12 volt" battery is way high. 14.2 volts is about the perfect CHARGING voltage.

Fully-charged "12 volt" battery should measure 12.6--12.7 volts. Anything above that is surface charge that won't last under load.

[j cAT]

your issues appear not to be with the charging system or battery. with not failure codes this looks like a fuel pressure issue..get the pressure checked with a pressure guage to ensure it is correct..

WHEN WAS THE LAST TIME THE FUEL FILTER WAS REPLACED ????

AS MENTIONED the voltage on a good battery charged at rest is 12.5-12.8 volts...

when engine on it can vary from 13.25-15 volts ....

in hot weather with a hot engine it will be around the 13.5 volt range @ 95 deg F.

[Schurkey]

Originally Posted by j cAT

in hot weather with a hot engine it will be around the 13.5 volt range @ 95 deg F.

Good point, and I forgot to mention it.

Battery voltage is temperature-dependent.

[UseDaGreyMatter]

Originally Posted by j cAT

your issues appear not to be with the charging system or battery. with not failure codes this looks like a fuel pressure issue..get the pressure checked with a pressure guage to ensure it is correct..

WHEN WAS THE LAST TIME THE FUEL FILTER WAS REPLACED ????

AS MENTIONED the voltage on a good battery charged at rest is 12.5-12.8 volts...

when engine on it can vary from 13.25-15 volts ....

in hot weather with a hot engine it will be around the 13.5 volt range @ 95 deg F.

fuel filter replaced not all that long ago and car has not got very many miles on it since so that shld not be problem, getting plenty of fuel to injectors.

[UseDaGreyMatter]

Ok to make it run they banged on the fuel pump, plugged in the Map sensor and blew out the fuel filter. ran codes then we got a 12 and a 51 ( prom error). I replaced prom with a brand new chip, it is still doing the same exact thing only not reading codes. could it be the computer?