alternator problems

[Steves LX]

I had to put a new alternator on a little over a month ago. I have noticed that anytime I put the car under a heavy load my voltage drops until I get my foot off of it. If the headlights are on you can actually watch them go super dim and then get brighter as I get my foot out of it. I just put a new belt on a few weeks ago. The other screwy thing about this is I had to get an alternator for a 89 F150 because the one I got for an 89 mustang, the bracket to mount it was clocked wrong and it puts the plugs down on the bottom of the bracket that the tensioner mounts to. The alternator is still the same 75amps as the one for the mustang. I did have to put a bigger pulley on it because it came with a smaller one and my belt was to big. So with that being said before I go spending money aimlessly I need some help. I had the alternator tested both on and off the car, it is good.

[mustangboy]

How old is your battery? Have you had it checked?

[Greg Seibert]

And be sure that the connector from your harness which plugs into the alternator looks good. That was a problem on many Fords. Some would even smoke at the plug end. On one of my GTs, the regulator (which mounts to the back of the alternator) went out, and the headlights would pulsate and dim at idle. It was easy to change. Got one off (my pile), not Keiths!:lol:

[quik lx]

I have the 200AMP SSP alternator and bracket assy (with wiring) if you wanna upgrade.

[ibstrokin]

I highly recommend using a ford 3g alt from a 94-95 stang, 140 amp. I put one on my white car and it eliminated all my issues. New they are about $180, used about $40-50. You have to do a little bit of wiring, but no big deal.

[kennebellcobra]

Definatly check the D plug mine was loosing connection on the dyno which would cause mass air voltage to drop and go lean:eek: I put a new plug on it.