[manoman]

i have a 90 5.0 mustang I DO NOT HAVE underdrive pullies, i did the 3G alternator upgrade and even had my stock small pullie put on so itll spin faster at idle, I installed a contour dual electric fan with a thermal activated controler. The car normaly idles steady at 800rpm and when the electric fan kicks on the idle with surge from 600 up to 900, what can i do to help this issue and if i leave it will it hurt anything. I thought 3g alternator was suppose to be able to support this amp load.

[samotrx7]

It does but sometimes idling that low it can't make that many amps. Try putting your idle up to 900-1000. Good luck and let us know how it works for you.