The day after Sun Tran launched its SunGO smart card system, Mary Harmon had supposedly racked up $650 in unpaid bus fares according to the transit line's computers. Until she paid, Harmon was told she couldn't ride.

Harmon was one of thousands of bus riders whose travels hit a pothole this week because of a major failure of the new mandatory fare cards.

Despite weeks of quiet tests of the new system, which requires riders to either pay the exact fare or use one of the SunGo prepaid fare cards, many riders found themselves carrying cards that didn't work or, like Harmon, showing they owed hundreds of dollars in fees.

If they didn't have cash to cover the fare, many were forced off the bus. And if they didn't have the exact fare, Sun Tran kept the change.

Effective Sunday, SunGo cards replaced a variety of other magnetic-strip bus cards. The new cards are available at all Sun Tran transit centers, many city offices, all Pima Community College campuses and Fry's Food stores.

Sun Tran concedes there is a problem with the new card - both with cards not working or showing huge debits. The company has dedicated an employee working with the smart-card-system vendor to resolve outstanding issues.

"We understand that some SunGO products are not being recognized at the fare box," said Kate Riley, general manager of Sun Tran. "We want to assure passengers that if this happens, the driver will let them board until we fix the problems."

But Harmon said that's not what happened to her on Monday, adding she could not possibly afford to pay the $650 in fees in order to start using the bus system again.

G. James, another rider, told the Star in an email that driver responses were inconsistent, with some drivers letting people on, while others seemed oblivious to the failure of the system and refused boarding.

Sun Tran officials said they are now working to inform all 400 drivers of the problem and are directing them to allow passengers on the bus if there is a problem with their new prepaid cards.

The bus line stopped accepting the other types of magnetic passes on June 29.

Officials are asking passengers to call (520) 792-9222 or email  with their SunGO Card number, contact information and a brief description of the problem they are experiencing.

Contact reporter Joe Ferguson at or 573-4346. Ernesto Portillo Jr. contributed to this story.