I have a 74 f-100 w/a 390, manual tranny. Recently when I turn the headlights on, my headlights,tailights,and dashboard lights surge. But it only does this when the engine reaches around 2000 or maybe a little less rpm and continues while I am on the throttle. It does not do this when I am warming up the truck or at an idle. Could it be a wire somewhere getting hot? Or do I need to get my alternator just checked? Any suggestion will be greatly appriciated.

 

mine does the exact opposite. surges at low rpm, then settles out as the truck warms up. so cant help you but feel your pain

 

happened to me and i tried everything, i finnally found the problem after replacing almost every thing.

check all the wires that come out of your voltage regulator and to ur alternator. i had a bad one, and there was an identicle one coming out of the same port. so i switched to the good one and problem solved.

basically its not letting ur alternator charge correctly and therefore surging ur electricall system

 

Surging ?

I would suggesting cleaning & securing all electrical connections and grounds.. especially the Mounting of the V/R....the 3 tabs on the V/R , the connector that goes on those tabs ....... Corrosion is the devil.

 

i've seen the v/r plugs break, the metal contacts get dirty and break. i had a similar problem. the connector is available at parts stores for like 5-10 bucks. i did it the expensive way and replaced the v/r first.

 

Thank you all very much. I will give it a shot and see what happens. Hopefully it will save whats left of my hair!!