PACHECO — At the 76 station on Pacheco Boulevard, midgrade gas on Tuesday ran $4.47 a gallon — give or take.

Note to bargain-hunters: It's cheaper on pumps numbers 1 and 4.

"Sometimes it goes in favor of the public," said county inspector Gil Rocha, eyeing one of the stainless steel "provers" rigged to the bed of a special testing truck. The gauge showed an extra four cubic inches of gas — about four ice cubes worth — when he squeezed out five gallons from pump number 4.

That discrepancy, not big enough for a violation, amounted to a lucky pumper discount of 1.6 cents a gallon.

Rocha, one of seven Contra Costa County weights and measures inspectors, moved on to a diesel pump, where he found "meter creep." The pump stopped, but the meter spun a few extra pennies. Rocha red-tagged the pump, wrapped it with wire and wrote up a notice for the station owner.

"Once you let go of the trigger it should stop," he said. "That would be something you'd get complaints about from customers."

Those complaints are rising with the boiling blood of miffed drivers. Last year, the county inspectors received 28 complaints of faulty fuel dispensers. The pace is more than 60 percent higher this year. Even with a recent retreat from the five-buck zone, the whippet-fast spin of the meters makes drivers leery. "One lady thought the meter was running too fast. I told her with the price of gasoline, the gallonage is going to run too slow, or the dollar amount is just going to fly by," said Patrick Roof, the county's chief sealer for weights and measures. "That's how it works."

The agency inspects each pump at the nearly 200 gas stations across Contra Costa about once a year. It also follows complaints. Violations come when the pump is off by more than 1.2 cubic inches per gallon — about a half of a percent, or two cents a gallon these days. Despite the suspicions, the number of violations remains low. So far this year, only one station has faced administrative action, and a $700 fine, for failing to fix a pricing problem, said Roof. Theoretically the owner could face a misdemeanor charge, but mostly the agency issues warnings.

Rocha, who returned last year from a 14-month Navy Reserve stint in Afghanistan, is nearing a decade on the job. After an eight-and-a-half year Navy career, he shopped the newspaper classifieds and found weights and measures. It meshes with his military background, he said.

"I view my job as consumer protection, and trying to level the field to make sure nobody's having an advantage over the rest of the industry," he said.

Inspectors make from $48,000 to $72,000 and their backgrounds vary widely, from degrees in marketing, to physics, to criminal justice, said Roof.

"We get a wide range," he said. "Nobody grows up wanting to be a weights and measures inspector."

Rocha, who holds a degree in civil engineering, said he has seen pumps wildly out of whack. The problems rarely seem intentional, he said, and often favor the pumper. "They usually fix those right away," he said.

At the 76 station Tuesday, few drivers said they worried about rigged meters. Scott Jones of Martinez, pointed to the county stickers on the pumps.

"I just kind of assume it's sort of regulated," he said.

Station owner Jagtar Bedi said he understands why people get upset. "We have to explain it to them every day. It's a matter of supply and demand. The prices we pay are higher." As for the meter creep, Bedi said customers often abuse the pumps, jamming them hard into their cradles, or driving off with the handle still lodged in their tanks.

"The way people abuse them, they don't care if it costs me," he said.

More than the meters themselves, attention among politicians and consumer groups has focused on "hot fuel" — when fuel temperatures rise above 60 degrees and the gas expands, cheating California drivers of energy they pay for. Roof said the county is awaiting a study expected later this year from the California Energy Commission, and may have to change how it inspects the pumps.

A recent report found that the average temperature of gas in California ran 72 degrees, meaning nearly one percent less energy in the tank for consumers, shortchanging drivers by more than four cents a gallon. The question is whether to force stations to install expensive devices to compensate for the higher temperatures, or raise the reference temperature above 60 degrees, which would increase the amount of gas drivers get for their money.

One thing that won't help: pumping when it's colder, said Susanne Garfield of the state commission.

"It's an urban myth," she said. "It's whatever temperature the fuel is delivered. It's pumped out at that temperature. Filling up in the morning doesn't work."

Better, it seems, to know which pumps are screwy, and in which direction.

"It's sort of like slot machines," said Ricky Clutter, up from L.A. and filling his tank in Pacheco. "You just hope you're the one that wins."

To lodge a complaint about a Contra Costa gas station, call 925-646-5250. In Alameda County, call 510-268-7343.

Reach John Simerman at 925-943-8072 or jsimerman@bayareanewsgroup.com