Hi Forum.

My 1969 Deville convertible drives great most of the time. In stop&go traffic the idle becomes very rough and there is bad shuddering...also the GEN light flickers on when putting your foot on the brake ?? ! The car wants to stall and will, if I don't shift to N to raise the idle when stopping....When pulling away after a stop light, there is a slight 'bog-down' which goes after the car is driven for a 100 yards or so ....?
The (electric - previous owner...) fuel pump also makes a loud 'tapping' sound during this rough running. The car also stalls out a lot when below 1/4 tank of fuel !?

Recent work done: pertronix, coil, plugs, cap, rotor, wires, fuel filter.

Could my alternator be dying and not charging the battery properly?

When replacing this should I go for a one wire or three wire ALT?

I have heard the 10SI Alt is a good one, can this be a straight swap into a 69 472 ??

Thank you for your help.... totally at the edge of my knowledge here :)

Cheers

Jon

Ireland

My 67 had a bad check valve for the brake booster . Leaked vacuum like a seive. Caused the same idle problems you're describing. I'd check for this or another vacuum leak.