Rich Beem, an unheralded PGA rookie who once gave up golf to sell stereos, fired a five-under par 66 in Potomac, Maryland yesterday to take a one-stroke lead at the Kemper Open.

Beem has missed the cut in seven of 11 events. But he fired seven birdies in his best round since last year's PGA qualifying event. He qualified for the tour and is playing because 30 El Paso friends pooled $70,000 for his expenses. So far he has won $24,500 dollars, $500 less than his qualifying prize.

The story yesterday was less satisfactory for Richard Coughlan, who missed qualification last season. The Offalyman shot a four-over-par 75.