FRESNO — Tainted gasoline sold at stations in California's Central Valley stalled vehicle engines Friday and left some motorists scrambling to find shops for weekend repairs.

Drivers who purchased unleaded regular from about 16 stations in a 50-mile radius around Fresno ended up with gasoline that was inadvertently mixed with diesel fuel at a tank farm operated by Kinder Morgan at Central and Maple avenues.

It is unclear how many motorists were affected by the bad fuel, but Larry Pierce, a spokesman for Kinder Morgan, estimated that 16 tanker trucks picked up fuel at the facility during the time of the mix-up, between 7 p.m. Thursday night and 4 a.m. Friday morning.

Kinder Morgan doesn't own the trucks or service stations, so Pierce said he could not provide a list of the stations selling the bad fuel.

One station that did get it was Bad Bud's, at Herndon and Cedar avenues in Fresno. Friday night, a transport truck was busy pumping the fuel out of the station's tanks.

Lorie Collins, a controller for California Fresno Oil Co., which owns the station, said the company was asking customers who got the bad gasoline to take their cars to repair shops and have the shops bill California Fresno Oil's insurance company.

"We feel really bad for people whose cars have stalled," Collins said.

The repairs would probably include having the bad fuel removed from tanks and changing the vehicles' fuel filters, she said. One estimate of the cost for that was about $200. Since many shops are closed on the weekends, however, it might be difficult for some to get the work done before Monday.

Pierce, of Kinder Morgan, said motorists who received the fuel should report the problems to the service stations where they bought the gas so they can pursue claims. He said Kinder Morgan would take care of the claims.

The company did not know how the mix-up occurred but is investigating to find out, he said. The fuel is refined at Martinez in the Bay Area and moved to Kinder Morgan's tank farm along a pipeline that parallels Highway 99.

At least one Costco station — in Merced — also received the fuel.

Jeff Cole, Costco's vice president of gasoline, said the error occurred at 6 a.m. and the problem was recognized around 9 a.m. The pumps in question were turned off after the problem was brought to Costco's attention, Cole said.

As many as 140 may have used the suspect pumps Friday morning, he said.

Michelle Delgado, who bought gas from the Merced Costco on Friday, said she filled up her vehicle around 7:45 a.m. but didn't have to drive too far before she realized there was a problem.

"When I started heading home, there was this terrible pinging noise," Delgado said. "Now I am on my way to go get a rental car."