[Rich 5150 69]

I`m asumming you have one, you`ll need to check it first, remove the vacuum line from your carb, pull your distributor cap off and suck on the vacuum line and look at your distributor vacuum advance plate while doing so it should move if not you`ll need to repair if your not moving the advance plate. If this checks out ok then you`ll need to look at your carb thottle pump, bad seal or plugged or out of adjustment.