Help! 1991 Suburban cuts out suddenly, immediately restarts. Tried everything.

[Edelbrock]

How would the alternator cause this?

If the alternator throws AC power (as opposed to DC) into your electronics or computer, it can basically cause the parts to have a seizure. Its like you getting hit by a taser while trying to draw a picture of a dog.

 

[fast 99]

How would the alternator cause this?

Excessive AC voltage "confuses" [for lack of a better term] overheats or overloads electrical devices. Like I said have seen it cause a multitude of odd electric issues.

Remember one vehicle, [Northstar Caddy] bight me real hard in the backside. I never checked the AC voltage until 2 days into chasing a horrible running engine. Disconnect alt motor ran like a champ.

Now I check it all the time. Not hard just attach a digital volt meter to battery posts, engine running. There will always be some AC just don't want a lot of it. Battery is a large capacitor. AC will be higher with a poor battery so I can't give you a hard number. Just that a .10v reading would peak my interest.

 

[Camar068]

Check the wires going to the distributor. I had a blue crimp connector on mine and it would lose connection there and there. If not applicable, carry on.

 

[MartinWD]

Even when driving?

yes