Bryan Leavitt uses one just about every time he fills his gas tank.

An engineer who works in Salt Lake City but lives in Park City "almost always" takes advantage of speedy "fast pay" gas pumps that let him fuel up at self-service stations without entering the building.During one recent fill-up, he inserted a credit card into a special slot, got it got cleared via satellite and filled his tank. The machine spit out a receipt and he was ready to roll.

Total credit transaction time: under 10 seconds.

"It's really efficient," Leavitt said. "You don't have to go inside and wait in line."

Gunnar Benselfelt, a Chicago businessman who travels extensively and does business in Salt Lake City, also likes the pumps.

"I think it's great. In Sweden we've had them for a long time and I always used them there. I'm glad we're getting them here," Ben-sel-felt said.

Chevron seems to be leading the installation of what is called "dispenser card readers" along the Wasatch Front, with 19 of them in high-volume stations. Other companies also are phasing in the pumps.

Conoco, for example, has two stations with such pumps in Salt Lake City and plans several more in early 1993, according to John Bennitt, Conoco's director of external affairs. The company has tested the pumps in other areas and has about 20 in Denver.

"It's proven itself to be very reliable and popular with motorists who just want to buy gas and get out," Bennitt said.

John Jelinek, merchandising manager for Chevron's northwest region, agrees. "It's really nice for parents who have children along in the car and don't want to leave them unattended."

Originally, there were concerns that the pumps would cut down on sales of soft drinks, snacks and other items inside the stations, but that hasn't proved to be the case. Instead, they eliminate lines of customers and free employees to wait on people who need to buy something in person.

There are a few drawbacks - the pumps cost the companies quite a bit to install, some early versions didn't work well and, occasionally, members of the public are reluctant to try the machines.

Paul Ashton, executive director of the Petroleum Retailers Association, saw the Utah's first set of fast-pay Chevron pumps go in at his Provo station.

Ron Reid, owner of Ron's Chevron, 504 S. West Temple, did the same thing. "Once everybody catches on to how it works, it just speeds up the operation for them."

The trick is to slip the credit card in and out quickly.

Business picked up slowly at first after his 12 pumps were converted to credit card capability, but on a recent afternoon, all pumps were regularly in use.