Then she realized Pump 6 was charging her for air.

"The dollar signs were running, but the gas wasn't," she said outside the station at 8101 Ritchie Highway, saying that at about 4:30 p.m. she watched the pump charge her for gas while she held the nozzle in her hand away from her car.

"Gas is expensive enough without having to worry about getting ripped off," said the 34-year-old mother of one who ultimately paid $63.15 to fill up her 1999 Chevrolet Malibu - $45.16 at the Exxon and $17.99 at another station. She said she usually fills up for about $30 to $40.

Krishna Shma, an employee of the station, said this morning a repair man has been called to fix the pump, which was covered last night with a plastic bag. A language barrier prevented further comment from Mr. Shma. The station manager and a representative from the company's corporate office in Dallas could not be reached.

Ken Ramsburg, manager of the Weights and Measuring Program at the state Department of Agriculture, said this morning he was unaware of any problems at that station. But state inspectors will investigate, he said.

"This is a serious issue. We take it seriously," he said.

He said Ms. Newsom is not the only one to complain about faulty gas pumps in Maryland.

His office received 724 gas-pump complaints in fiscal 2008, which ended Monday, up from 515 complaints in fiscal 2007. Mr. Ramsburg estimated 75 percent of those complaints were legitimate.

Ms. Newsom's ordeal started when she stopped at the gas station to fill up her 12-gallon tank.

While she was pumping gas at Pump 6, she heard a woman using Pump 5, which is on the other side of Ms. Newsom's pump, complain something was wrong. That woman said she wasn't getting any gas, leading Ms. Newsom to check her pump and find she was having the same problem.

Ms. Newsom said she had to get a store employee to shut off the gas pump, but only after it charged her $45.16. She argued with a manager at the station and eventually called police. She said he owed her a full refund, but she settled for half because her car's gas gauge is broken.

"He was like, 'Well, you can get half or nothing,' " she said.

Police said they did not take a report. A department spokesman said an agreement was reached between the station and the customer.

While the police were talking with the manager, however, Ms. Newsom said she learned something that made her even more angry: This has happened before.

Ms. Newsom said the manager confessed to police the pump will occasionally charge for gas after the auto-shutoff engages.

"If he knew about the problem, he should have put a bag on it before I drove up," she said.

Ms. Newsom said she didn't know what happened with the woman at Pump 5. She said she lost track of her while talking with the manager.

Pump 5 was still is use last night. A man who used it about 6 p.m. thought the pump overcharged him: he said he expected to spend $77, but was charged $85.83. But he had no proof.

He attributed the extra $9 to the inaccuracies of his SUV's computer and the fact each pump can shut off at different levels.

"What are you going to do?" Jamie Jacobs asked.

There was no inspection sticker on Pump 6. The rest of the pumps at the station, including Pump 5, were inspected in September 2006.

Mr. Ramsburg said his staff inspects pumps every 18 months to two years, but he said there is no set restriction requiring inspections every two years.

While unable to say what - if anything - is wrong with the pumps in question until they are inspected, Mr. Ramsburg said it is possible for a pump to charge for gas without dispensing any fuel. He said there is a hose inside the fuel pump hose to take vapor back into the machine. If that vapor hose is punctured or frayed, the gas can do a U-turn mid-hose and return to the machine, he said.

"The gas is still flowing through the meter," he said.

Mr. Ramsburg estimated about one-third of the gas-pump complaints his office receives are for "computer advancement" though. He said that is when a pump will start charging for gas before any actually flows.

He credited recent Internet posts and media coverage for driving up the number of complaints.

"I think people are more aware of it and they are upset about the price," Mr. Ramsburg said.

Ms. Newsom said people need to be aware gas pumps can over-charge them. Both she and Mr. Jacobs said they don't watch the display when they pump gas.

"If I hadn't heard her, I probably would have pulled away (without noticing my tank was half empty)," Ms. Newsom said.