Hello all, I found a weird thing in my diagnostic testing, my battery drains and does not charge after running the 318 engine, I tested back to alternator and the power wire on the back shows no voltage until it is disconnected, then the wire shows same voltage as battery. with the power wire disconnected on the back of the alternator and the keys turned on, the voltage pins my multimeter at 50 volts, tried 100 volt setting and pins the meter also. I thought I would stop and mention this to you guys and wait to do further diagnostic testing.
Thanks for any help.

 

What is voltage on the output terminal of the alternator with the engine at idle? If it is around 12 volts, or less, time to have the alternator tested.

 

Thanks for your reply, I am wondering if I can test the voltage regulator in the computer by doing something called a field test (I think it is what it is called) I can put a fully charged battery in the van and let it sit for 2 days and it will not start, also when I start it right away, it takes 50% of the battery and will not charge, the needle on the charge meter is lower and steady, I look at the gauge as I put on headlights, signal lights etc and the needle on the gauge stays the same, no movement at all.

 

Check output voltage AT the alternator, with the engine idling. See what it says. Should be 13-14 volts. If it isn't, pull the alternator, and have it tested. If it test good, voltage regulator is bad.