Low amp gauge reading

[depthcharge711]

I have a 72 F100 390 4spd no a/c. At idle I run around 750rpms . When I look at my aftermarket amp guage(Dolphin Brand) It is sitting right above 10V. when I rev the engine up to 2500+ rpms she will get to almost 12V on the gauge. I have pulled the positive cable while she is running and she doesnt die, so the alternator isnt fully dead. I just replaced the voltage regulator and the battery. Is there a test to see if the alternator is failing or should I just replace it. I ask because I dont want to replace it and then the system still doesnt charge. I was always told the amp gauge should read around 14 while driving.

Any help would be greatful.

I must add that I never have an issue starting her, she never sounds like the battery is dying that is.

[fordman]

the regulator is what controls when and how much the alternator charges. new parts are sometimes not good. but the gauge could be reading wrong too. try to test how much i tis putting out with a meter. or take it to the parts store and they will test the system for free.

[depthcharge711]

What kind of reaindg should I be looking for with my Fluke multimeter?

[kuz367]

With the truck running take a reading at the generator and record it. Then take another voltage reading at the wires at the back of the gauge. They should be very close to each other. Then compare those readings with what the gauge says. I agree with fordman, chances are the gauge is inaccurate. I would trust the Fluke alot more than the gauge

Kevin

[Thunderfoot]

What kind of readind should I be looking for with my Fluke multimeter?

At the battery with the engine at idle it will be very close to the same as the with the motor not running (the alternator wont charge much at idle) then when you rev the engine up a bit it should be 13.5 to 14 - 14.2 or so...