Ok.....I have a 94 f150 4X4 extended cab and I thought I was having alternator trouble, I tested the battery and it was charging at 12 then it would jump to 15, so I changed the alternator and now things seem to be worse. When I start the truck it sqeals and the volt meter in the truck drops to nothing. Only when I get it up 40 - 50 mph does this go away and the volt meter comes back to normal, but when I slow down the volt meter drops again. When I am going slow I can't even turn on the fan. I heard that the regulator has something to do with this but the alternator is new and the regulator is part of the alternator. Can this have something to do with the belt tension?

 

302?? straight 6?? check belt tension,double check all your connections.

 

Could be the tensioner, could be the new alt too. Where did ya get it?

Adrianspeeder

 

f150 4x4 302 ext cab, I just put in a new alternator and battery. I had to change the battery as the alternator that I put in was cooked because my old battery was shot. but the new alternator and battery did not fully fix that problem, the volt meter seems to be fluttering when the vehicle is at idle. It doesn't flutter much, the gauge may move 1/16". Could this be the tensioner?

 

Correct voltage when idling or running at speed is 13.8 volts to 14.8 volts with or without a load. If the battery is very run down and the alternator is charging it back up then sometimes it will show low initially....but after say after the engine has had time to warm up and re-charge the battery the voltage should be back to normal.

If you are getting low voltage at idle you have a bad alternator/regulator. If you have high voltage, you have a bad alternator/regulator.

Of course this is assuming that there are no dirrect shorts in your electrical system and other things are functioning normally and wire are not corroded.

I have seen these symptoms from bad battery cables and thath was all that was wrong. Inspect closely the cables...sometimes they are corroded inside the sheathing too....not just on the surface.

 

It's very common for dirty battery terminals or poor grounds to cause these problems. Remove, clean, & tighten all 3 black wire terminals & the 2 on the red wire at the battery & starter relay (on the inner fender).