Surging problem on an alternator - 1993 Buick Regal

"Burned up 4 alternators" isn't a very helpful description, so what went wrong? Diodes? Regulator? Stator windings? Rotor windings?

A basic self-contained machine sensed alternator is almost bulletproof when the wiring is good and secure but they aren't tolerant of surges and they will surge whenever a good connection with the battery is lost while at speed.
An intermittent connection could be anywhere in the supply or ground and although rare an internal break in a cable, a poor connection inside a crimped terminal or even a bad connection inside the battery.

If the alternator is a smart charging type it adds new fault possibilities to those above.

How do you know it's surging? In any case, about the only thing that can cause this is a faulty regulator in the alternator, or a poor wiring connection (e.g. battery cable or at alternator).

the voltage to electronics is critical and any loss of generated power from the alternator will result in under voltage to the ECM
that in turn throws out the set parameters of the sensors and so the ECM goes into reduced power mode
the surging could be an intermittent fault in with the alternator , failing cells in battery or loose or failing drive belt
before you spend money on new alternator and battery, you can have the battery load tested and the alternator bench tested as the fix can be reasonably simple

Try replacing the wiring harness that connects to the top of the alternator. They vibrate and the wires inside break. They are only about twelve dollars.

could be alternator

have the output of the alternator checked as the surge is from the alternator regulator . Check condition and tension of the drive belt

it needs a new alternator its going out on you or maybe a loose wire on the alternator check the wires and at autozone for free they will test the alternator before replacing it

Replace the alternator,the diodes in the alternator are failing.

The surging is from the alternator not charging enough volts.Check the volts at the battery,while it is running,it should read about 13.65 to 14.25 volts,if it is less than this replace the alternator,it should be checked with the head lights on,and fan on high blower setting.

Get a good alternator not a cheap one.