328 Hard Accel, alt light came on

The alternator belt breaking or coming off -- do a visual for this first! That warning light will often come "on" when something goes haywire electrically within the alternator, but its primary function is to detect a broken, or missing, alternator belt.

 

Another likely suspect is the voltage regulator. Check that all the contacts are clean, tight and free of corrosion. Make sure it has a good ground. Also, check the fuse that provides the positive to the regulator.

 

I can offer no technical support, but my goodness do you have my moral support.

 

Simple stuff first. Sniff around and find the belt.Make sure it is not slipping.You should not be able to turn the Alt pulley with ease.If so tighten the belt to spec.Mike

 

The 328 alternator is tucked between the engine block and the 5-8 exhaust header and sort of "under" the AC compressor (but you should be able to visually confirm if the alternator belt is still present, or not, by just looking down at the outermost pulley on the crankshaft):

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The VR is a component mounted on the back of the alternator -- item 31 here:

https://www.ferrariparts.co.uk/diagram/ferrari/328-gtb-gts-(1985)/043-electric-generating-system

(But more usual to remove the alternator and replace the VR on the bench, then reinstall the alternator).

 

If the belt is still present and reasonably tight, it's almost certainly an alternator internal electrical problem -- that's a very reliable belt path with both pulleys having about a 180 deg wrap angle.

 

Nothing too specific. High RPM at high load would be the most vibration, heat, etc., but electronic gizmos have a long history of failing at random times . Is the alt warning light still always "on" regardless of engine RPM? If so, still make a voltage measurement between the two battery terminals with the engine running to confirm it's kaputt.