electrical gremlin

[Smurfslayer]

I need some (more) help. My 91 EB has some sort of electrical issue ; when I start the truck, or, when I'm idling or below about 1500 rpms, the lights 'flicker', volt gauge bounces rapidly. While driving, the volt gauge reads a tad high.
I've checked the ground, voltage reg / alt, and they appear fine. it's otherwise running good. Any ideas ?

TIA

 

[fixer]

i had a similar problems in my '92 Ranger twice.

first time it was just a dying battery, second time it was a dying starter.

check the battery to make sure that all cells are full, if not, refill with distilled water. use one of the testers to make sure that the electrolite in each cell is still good and also check for sulfating.

most local auto parts stores will check the starter, and it takes about 5 minutes to remove or install it.

 

[MattHarrell]

Yeah, and when I had this problem it turned out to be the alternator.

A couple of things to check:

check both battery cables. If they're really old you might just replace them.

check your ground straps to see if any are worn

use a ohmmeter and check the resistance across the various parts - battery neg to frame, battery neg to engine, engine to frame. I don't think it should be more than a couple ohms.

hook a voltmeter up to your battery when the truck is off and ensure the voltage is in the normal range.

hook a voltmeter up while it's running. The manual should mention the right range but I think it's like 14.0 - 15.0 volts.

Good luck

 

[ishichar]

One dark lonely night on the Northshore of the island of Oahu I experienced a similar problem with my '91 Ford 5.0 running a custom 100 amp. alternator. The battery readings were 'haunted' and voltage would jump all over the place while lights flickered. Finally 5 minutes after passing the last street light in Kahuku town everything died. Desperate measures; including a 'whack' on the side of the battery managed to get started up again.

Trouble shooting the problem the next day at an automotive electrical shop revealed the bad battery but also a bad voltage regulator. The battery and voltage regulator were replaced instead of the whole alternator at a considerable savings.

 

[fixer]

"haunted"? you didn't pass by an old native lady hitching a ride before you had these electrical problems, did you?

just thinking of all the ghost stories i've heard from hawaii.

 

[ishichar]

Actually, the week before winter surf had uncovered an old Hawaiian grave and someone turned in a skull into the stationhouse. It was recovered by State workers but the feel of something looking over one's shoulder was very evident in the pitch black darkness.

 

[Smurfslayer]

Thanks all. Matt sent me a mail, I checked resistance & voltage at lunch, both look good as measured by my multimeter - no resistance bat. neg. to chassis, or engine. Voltage constant, steady 12 eng. off, 14 engine on. measured at battery, bat. pos to chassis ground, alt pos to chassis & alt pos to bat neg. all read 14 steady volts. I verified the lights were still fluctuating as was the voltage gauge. ground cable looks to be original. battery is 11 months old, Motorcraft. Alternator & voltage reg. replaced last year when I 1st noticed the (then sporadic) problem. nothing else electrical I can think of that could help diagnose the problem... I suspect the battery neg. cable...

Thanks again.