TRENTON, N.J. - Throughout March and because of rising gasoline prices, inspectors from Mercer County??s weights and measures office have been paying unannounced visits to stations at 12 of the county??s 13 municipalities (Trenton has its own weights and measures department), checking to ensure what is displayed on stations?? gas pumps corresponds to what flows into motorists?? gas tanks, NJ.com reports.

John Worth, superintendent for Weights and Measures for Mercer County, said gas stations are supposed to be inspected at least once annually or if complaints are reported.

Last year, the department received 15 complaints specific to gas stations. To date this year, it has received 10 similar complaints, according to spokesperson Julie Willmot, who said the number of complains is above average but typical for periods when gas prices are high.

During inspections, the department checks the pumps to verify accuracy and to test the different gasoline grades for the presence of water. They also check to make sure octane levels are correct.

For pumps that fail inspections, inspectors affix a reddish orange sticker to them, and seal the nozzle until the station owner fixes it.

"It seems like in a matter of days -- and sometimes more than once daily ?" consumers are seeing prices ratchet up at their local gas stations," said County Executive Brian Hughes. "We want to ensure that not only are they getting exactly what they pay for at the pump, but that gas stations are abiding by rules that limit how frequently they can raise prices, and how prominently they must display prices and whether those prices are for cash purchases or credit purchases."