Is my belt slipping?

Well this all started the day of the dyno but we are not sure. On all of my pulls you can watch the FP drop a few PSI then come back. At first i thought my belt may be slipping. But my tuner thinks it is not because the FP came back. This happens in the upper RPMS. The car is making around 8 PSI but the boost never falls on the gauge. He suspects my FP drop is due to the pumps needing more voltage.

On the street under WOT after about 5k RPMS the battery light on my dash will come on, go off and come on. It flashes a few times maybe once or twice. Now the only thing i can think of is. The belt is slipping and causing the alternator not to prduce enough juice and the light is coming on briefly. Or that there is a big strain for power to both of my fuel pumps. What do you guys think? There is no evidence of wear or anything on the belt either.

Dave

Regarding the batt/alt light coming on and off around 5K @ WOT; I had the same problem too. I replaced the brushes in the alternator and the problem went away. The brushes are cheap around $12.00 from NAPA parts. Mine were worn down to the last .25 inch.

thats interesting. The alternator is pretty new. Less than 1k miles on it. I dont think it would be worn that quick would it? Something to look into since its cheap and easy though

Is the alternator a new OE Ford or some parts store reman? There is a chance that it has a bad regulator and it is cutting voltage at higher rpms. That or you might have a bad ground somewhere and that will cause all kind of problems on a car running so much electrical stuff. I would recheck all you grounds and power connections and then go after the alt.

I agree with Snake Is 100%. Go over your electrical connections first. Then I would suggest replacing the regulator and see what that does for you.

I ordered some new battery terminals and i am going to reground the car with a nice 8 gauge wire. I am also going to run an 8 gauge wire to the trunk for the pumps with a block to i can run both of th epower wires for the pumps into that. This way i know they both have good connections. The alternator is not OEM Ford either. How much does the regulator typically run? Thanks

Dave