Like the Ramones, the family-affair funk outfit ESG began writing songs because they couldn’t play covers properly.

The four Scroggins sisters were raised in the hardscrabble South Bronx. Their mother bought them instruments in the mid-1970s to keep them inside and out of trouble. Renee played guitar and sang lead, Valerie played drums, Marie played congas, and Deborah played bass.

The quartet was enamored of James Brown, especially when he “took it to the bridge” and let the bass and drums go on their own. Though the sisters practiced hard and could play, they knew people

would notice if they made a mistake covering “Cold Sweat.” So they began writing their own songs, which, more often than not, were all “bridge.” Vocals were an afterthought — once you saw titles like “Hey” and “ESG,” you already knew all the lyrics — but they soon developed an open, spacious instrumental sound that distinctively blended Latin pop, disco, new wave, and rock.

The owner of the 99 Records label, Ed Bahlman, saw ESG while judging a talent show in 1979. He signed the band to his label and became its manager. After several singles and EPs, the full-length “Come Away With ESG” appeared in 1983.

During this period, ESG developed a reputation as a brilliant live act. It opened for the Clash, Public Image, Ltd., and a Certain Radio. It played opening night at London’s famed club Hacienda in 1982 and closed the legendary Paradise Garage disco on its final night in 1987. Critics loved the band, but it remained little-known outside New York. By the late 1980s, the Scroggins sisters had moved on, taking jobs and raising families while recording sporadically.

Hip-hop producers, however, kept listening. Samples of early ESG songs “Moody” and “UFO” showed up in hits by Public Enemy and Big Daddy Kane, though remuneration was slow to come (a situation the band lamented on a little-heard 1992 EP, “Sample Credits Don’t Pay Our Bills”).

Fortunately for ESG, trends are cyclical. In the last few years, the vintage dance underground has come back in force. The British reissue label Soul Jazz assembled the definitive ESG compilation, “A South Bronx Story,” in 2000. A short album of new material, “Step Off,” followed in 2002, and now the band returns with its second batch of new material since being rediscovered.

While ESG has always stripped music to its rhythmic essence, “Keep on Moving” is the band’s most skeletal record. The opening track, “Purely Physical,” is nothing more than a Roland 808 drum machine, a rubbery bass line, and Renee Scroggins’s sultry vocals, which are half-spoken in a cadence reminiscent of Missy Elliott. At 6 1/2 minutes, it feels more like a two-minute sketch of an intro, repeated three times.

The title track fleshes out the sound slightly with a commanding bass line that connects ESG back to new wave and a welcome timbal solo. By the perky “Insane,” the record has hit its stride, but the continued presence of a drum machine is troubling. Valerie Scroggins was once known for her mechanical precision, and here programmed beats have partly replaced her, to the album’s detriment.

“The Road” is a new wrinkle for ESG, a heavy, almost industrialsounding instrumental that combines acoustic and electronic instruments. While the sonic heft of the groove is impressive, it too becomes wearying without enough ideas to sustain its six-minute running time.

“Everything Goes” comes closest to capturing the easy swing of classic ESG, with bright and warm guitar accents and a radiantly optimistic vocal from Renee: “Hey world! Everything goes!” The mood doesn’t last long, though; the next song, “Ex,” takes a dark turn as Renee addresses the new girlfriend of an abusive lover over a stark and haunting piano refrain.

The Scroggins sisters remain defiantly original and committed to lean and danceable fundamentals. But “Keep on Moving,” even with several weird and wonderful moments, isn’t all it could have been. There’s a spark of life in every song that never quite takes. By most accounts, the band’s concerts are still something to behold; in a live context, these songs may yet catch fire.