About one in ten gas stations across B.C. have been found to be underselling customers anywhere from a few dimes to a few dollars on a fill-up.

Many station managers say they have fixed the problem since they were caught by inspectors from Measurement Canada, the federal government's gas station watchdog.

"It's few and far between but it does happen," said Petra Zatzke, a manager at a Super Save gas station on Highway 97 near Kelowna. "The older the pump, the more likely that there's going to be mechanical failure."

In 2006, Zatzke's station was tested by government inspectors. They found that of her 10 pumps, seven were working normally.

But two were holding back about half a litre of gasoline on a 50 litre fill-up -- about 75 cents' worth of gasoline. A third pump was underdispensing about 750ml -- more than a dollar per fill-up.

It may not seem like much, but it adds up to a few cents a litre -- equivalent to the price hikes of the carbon tax of the provincial Liberal government.

When Zatzke got the government report, she fixed the pumps, and now has an independent company check the pumps every year.

"Really and truly, in order for the customer to be fully protected on a regular basis, Measurement Canada has to regularly check gas stations," she said.

That Super Save isn't the only one. Gas stations across the province under most brand names have failed government tests.

In 2005, the Gordon Head Shell station on Shelbourne Street in Victoria was caught underselling by about 1.7 litres on a 50 litre fill-up -- or about $2.50 worth of gasoline.

It was fixed after the inspection and the station has since changed management, said the new manager, Serkan Tabanli.

"I didn't want customers to suffer," said Tabanli.

In 2006, Nakusp Shell Service east of Vernon was found to be giving out 2 litres less than its pumps were saying -- the most of any B.C. station in the past two years.

The manager, Warren Jones, said he shut the pump down immediately and hasn't reactivated it.

"I was very concerned about it," he told CTV News over the phone. "Measurement Canada does a good job and we look forward to them coming -- because it means our pumps get more accurate."

A spokesperson for Shell said that they investigate pump accuracy after they receive a customer complaint.

"We strive for accuracy and we do comply with federal and provincial requirements for pump calibration," said Jana Masters.

Cedar Hill Petro-Canada in Victoria failed in 2005 -- its first failure since 1999.

Petro-Canada spokesman John Hamilton said his company has standards that are higher than the federal standards.

"We have standards that we've set ourselves that are five times stricter. We don't want to leave any wiggle room, we want to be on top of that," he said.

All companies pointed out that pumps can be off in favour of the customer as well.

For example, the Super Gas owned by Grewal Motors on Scott Road in Surrey was doling out over two litres on a fill-up for free within the past two years.

But according to Measurement Canada findings, 75 per cent of the time it's the customer that loses out.

With a report from CTV British Columbia's Jon Woodward