Electrical Problem! 1981!

[scubahard]

I seem to have a slight electrical problem. When I start my truck and when it can idle the dial says "13" volts. AS soon as I start driving and get on the freeway my voltage slowly starts to decrease. As I cruz the voltage drops to "8" volts and in the red zone. Then when I get off the freeway and stopped at a red light my voltage increases. I have been tracking the pattern of the voltage fluctuation for about two weeks and this is the characteristics of it. Some times the dial decrease to the lowest registered setting. I am afraid that the truck might die. Each day the voltage dips lower and lower.

Could this be a problem with my ignition system? There seems to be a short somewhere, obviously, but it seems to be "RPM" or "speed" dependent. Any feed back would be great for trying to solve my problem. I know this is a vague description of my problem, but maybe some pointers where to start looking. Thanks.

 

[or2play]

I think I would start at the alternator first. If you have a multimeter, start the engine and put the meter on the alternator's batt terminal. Then advance the throttle by hand and see what your volts are. Might be simply bad alternator, if you have good voltage, just move the leads up stream until you find were the voltage drop is. Also check for any bad connections, or chaffing wires and what not.

 

[bmpaul68]

I also would suspect the alternator. if you don't have a meter it's not that big of a deal to pull the alt and take it to autozone (or wherever) they can test them for free.

if the alternator is good then you definately have a strange problem on your hands.