[Blackbirdws6]

I contacted the alternator manufacturer and they said it could be belt slip. I don't see any dust and the belt still looks good but perhaps this is still happening. They mentioned trying a slightly smaller belt since they fit their alternators with slightly small pulleys to help with idle volts. So perhaps its tight but not tight enough.

I did not have the issue before but I actually had a significant alignment problem so the belt rode the balancer a bit towards the rear. Maybe this created more tension which is why I never had the issue before.

The 2nd fuel pump comes on around 4 psi and I will be making around 10 at that RPM where I am seeing the drop so I don't think that's it.

Ltb1ow is going to let me borrow a stock size pulley which I will toss on the alternator and give it another shot. If that doesn't do it, I will likely just buy a unit from the local store and see if there is any change.