Before I start this post, I must confess that while the Vulcan 3 liter in question is not in a Ranger, it's in one of my other Fords, our trusty and worn '94 Tempo. However, since the engine and charging system should be about the same, I though maybe I could sneak this in.

About a month ago I replaced the alternator again, the second one in a year's time. The other day I replaced the battery, which was only two years old. Today, on a trip of about 75 miles, I discovered I'm STILL having trouble.


When alternator one died, it signaled it imminent demise by causing the lights to flicker about the time the engine got good and warm. The flicker was independent of engine RPM, and would sometimes go away if I revved the engine at an intersection. Eventually the AMP light came on and I had to replace it.

Alternator Two died without causiing the lights to flicker, but this time when the AMP light came on I hooked up my VOM to it and discovered it was overcharging. I replaced the alternator.

A little over a week ago I was left stranded when the vehicle began missing, and then began to lose power as (I later discovered) the alternator ceased to crank out enough power to keep the fuel pump going and the fuel injection functioning. The battery was dead, but recovered enough that I was able to start it and drive up onto the tow truck (A GMC! ARGH!) when it got there.

The next day I fired it up and let it run for awhile. It ran great at first, but after about half an hour it died. I put the battery on a charger, and the next day tried it all over again. This time I hooked up my VOM, which read a nice 14.5 when the engine was cold, but as the engine (and the alternator) warmed up, voltage dropped off, and I shut it down when it reached 11.3 volts. I also checked the cells of the battery (before discharging it) and found that each cell was good. However, by this time I was utterly bumfuzzled, so I took it to a garage (Something I NEVER do!!), and after getting out all his fancy equipment, he checked the battery with a hydrometer, and we discovered that it couldn't get any ***** to float.

Sooooo..... I replaced the battery. However, I discovered today that the alternator is still losing its ability to charge after it warms up. After my trip today I got out the VOM (after noticing the turn signals were not blinking fast enough) and discovered the alternator was charging at 11.6 volts.

I'm stumped.

Any ideas?

I have to say Grover has been getting driven a bit more recently. I suspect he got jealous and sabotaged the Tempo.

 

I'm not familiar with a '94 Tempo. But if it has an external voltage regulator, that regulator could be at fault. When I did battle with a similar problem on my '84, the problem turned out to be a bad connection between tha negitive battery cable and the engine block. I would suggest taking appart and cleaning all of connections in the charging circuit including the ground connections. If you'r lucky, and it is a bad connection, at least it won't have cost too much to fix the problem.

Of course, the real question is why did you name the '54 "Grover"?

Good Luck

 

Why did I name my '54 Grover?

Wellll......

My truck is blue. I am a Sesame Street fan (from waaaaaay back, of course). Grover is probably my second favorite Sesame Street character (Animal being #1), and he just happens to be blue.

So there you go.

 

I would suggest taking the alternator off and taking to get it tested (like at Autozone) and find out if it is the problem. Then I would go after the regulator as suggested.

 

The '94 Alt will have a builtin regulator.

 

I think you have a bad regulator
with the charging going down hill when hot
I would take it back to place of purchase and get a refund
with three bad units in so short of time there rebuilder
must be cutting corners
find a new sorce

 

Well, after thoroughly cleaning all connectors and lubing them up with dielectric compound to make DANGED sure that I was getting a good connection, I fired it up again and got the same results. Today, that alternator is returning to the store where I got it.