charging issues? (yes, I searched)

[Forrest Nearing]

here's the skinny...



I've got a 91. 5 D250... I'd say roughly 2 months ago (right around the time I started using the AC for the first time (I've only had the truck since November (and put almost 30k miles on it!! )))



anyhow, around that time, I noticed that when I'd pull up to lights and stuff, the voltage would drop down... as I turned the AC fans down it wouldn't drop as low... headlights, reverse light, brake light, etc. all make it drop, and it'll bounce w/ the turn signal...



now, this is ONLY at low engine speed... IE, when parked w/ the lights on or w/ the thing in drive (auto) w/ my foot on the brake at a light...



once I'm moving the needle moves back up to just a hair below the 3rd hash mark (I coulda swore it used to sit rock solid at the hash mark, but it's so close now, I honestly can't remember, but I really think it used to sit there!)



so I've been driving it like this for a while now and it hasn't really bothered me, but I'm about to head up to the mountains and put another couple thousand miles on the old girl, and I want to try to resolve this lest I be stuck on the side of the road w/ no cellular signal, etc.



so I went to the parts store and bought an alternator because the dip**** behind the counter said they were internally regulated and it was displaying symptoms of a questionable diode...



I put the alternator on... same thing...



then I hopped on TDR (shoulda done it first, I know... I know... ) and learned that it is in-fact externally regulated and that it's regulated by the computer (as mine is a 91. 5/intercooled) so I cleaned the terminals on the computer and wiggled a couple wires...



then, I noticed something that bore a STRIKING resemblance to a voltage regulator on the firewall... hmmm...



so I yanked it off and went and tested it, and it tested good (bummer), but on a hunch (and just to have a spare in the glove compartment) I bought a new one and came home and put it on...



before I fired up the truck, I tested the ground at the case of the voltage regulator and it's good... fired it up, and I'll be damned if the voltage wasn't LOWER!!!



re-installed the old regulator, and now it's doing exactly the same thing... the ONLY other thing I can think of is maybe a dead cell in the battery... it is a good couple years old and it's a cheaper battery (came w/ the truck) like a wal-mart special or something...



I'm probably going to take the alternator back tomorrow and buy a new battery "no sir, I swear I haven't installed the alternator yet... look, it's still got the v-belt pulley on it, my truck uses a serpentine" LAST summer I actually had a battery die on me an hour from civilization... I had recently replaced the alternator and regulator and had SPARES of each in the trunk! (gotta love lifetime warranties! I had never had a BATTERY go out on me!?



anyhows... ANY assistance, thoughts, ramblings, etc. are very welcomed! I'm pretty good w/ cars on a whole, but this is my first non-ford vehicle (after a good 25-30 Fords!!!) so I'm not as familiar w/ all the neuances of this truck. I sure do love it though!



if you've made it this far, thanks for reading and thanks in advance to anyone w/ any ideas/assistance!



take care,



Forrest

 

[BushWakr - RIP]

This may sound dumb, but... what is you idle speed???

If it is too low that will do what you describe. Ferget what the darn manual says, set your idle aroung 800 RPM with AC on.

Also disconnect your temp sensor that triggers the manifold hearters and see if that helps, maybe its kicking in by mistake.

A couple dead cells in the battery is a possibility, you can have it tested on a carbon pile to see how it holds up under serious load.

Keep us posted on your progress, I'm interested in the outcome.



Bob.

 

[Forrest Nearing]

Bob,



I've considered a low idle condition, but I haven't changed anything, and the voltage drops even with just the fan on, just the lights on, etc. it didn't used to do that... I'm just not used to vehicles "backing off" the idle setting... w/ all the accessories going, I have to give it a fair amount of pedal to get it to come back up... I couldn't imagine idling it up to that speed... w/ a stick MAYBE, but not w/ the auto...



I'll post an update tomorrow... hopefully it'll be good news!



thanks,



Forrest

 

[BushWakr - RIP]

Forrest, even an auto is ok to idle at 800. When my auto was stock it would idle 800 in "N" then once in "D" it was down to about 725 RPM, perfect !! With the AC on it dropped to about 700 RPM and was right at the line of showing a bit of mirror shake.





Bob.

 

[Forrest Nearing]

Bob,



well, I was brousing through TDR and was reading up on pump tweaks and decided to go take a look at the pump... just to familiarize myself w/ it...



ended up turning up the fuel which increased the idle... I turned it back down, but it's higher now, and of course the voltage isn't dropping as bad. I think I'm still gonna buy a new battery just on GP, but all of a sudden I'm not so concerned w/ the volt meter, I'm diggin' the newfound power!



I'll post any updates on this situation. thanks for your help!



Forrest

 

[mblair]

voltmeter

Have you put a voltmeter on it to compare it with the gauge?

I'm no electrician, but I check battery voltage with a meter without running. Then start and check, then turn all accessories on and check to see if it holds load. If it holds voltage above 12. 5-13 volts (with all accessories on, wipers, lights on high, a/c running full speed, etc) you may need to run speed up a bit. My alternator quite working a few months ago. A rebuilt one was over a hundred dollars so I just bought a brush set for about 6 or 7 dollars and it's works great.

If the battery shows full charge, you could take wire off your solenoid at the injector pump. Then crank for about 20 seconds. voltage should stay I believe above 10 volts. I have a 50 amp load tester I bought at Harbor Freight for $19. 00 that tests. Or, you can just take it to Autozone or someplace like that and they can test it on th truck. If it is a bad battery, Sam's Club has a group 31 commercial battery for $50. 00. The same battery is 65. 00 at WalMart. I've had one in my truck for several years and it still works great. Good luck!

Max

 

[Forrest Nearing]

update... I turned up the fuel which raised the idle... I turned it back down, but it's still higher than before... that helped a good deal, though I might give the power screw another 1/4 turn... just to increase the idle of course!



I went ahead and bought a new battery today because I didn't know the history on the old one... bought a big nasty group 65 bad boy... haven't really put it to much of a test as I'm currently in the middle of cleaning my K&N (want all my ducks in a row for my road trip!) but it doesn't seem to have changed the orientation of the volt meter...



oh well, I've checked the alt, the regulator, the battery, and all the connections... guess this is just how this truck is!



thanks for all your help guys,



Forrest

 

[hdm48]

Ok, here is one for the books. AFTER you have checked the voltage at the battery with all the symtomes simulated, and your sure there is a low voltage issue present try this,,,



connect a wire from the battery ground to one of the screws holding down the voltage regulator.



Now what does it do?





dave

 

[Forrest Nearing]

I'll check that, but I did test the ground at the case of the regulator...



I think I'm just being nit-picky at this point! LOL!



but I will give that a shot!



Forrest