Mark Webber's Abu Dhabi Grand Prix weekend got off to a shaky start when he was forced to retire his Red Bull with technical trouble in Friday practice.

The Australian completed only 21 laps in the evening session, 13 fewer than his teammate and the quickest man on the Yas marina track Sebastian Vettel.

Webber was called back to the pits after water was seen leaking from his car as he left the garage for a heavy fuel run.

He later confirmed it was a KERS issue, although different from that suffered in India the previous week.

"(It's) a pain. Obviously it's not great when your mileage is limited, it's nice to have as much as you can in," Webber said.

"We're not to the bottom of the fault yet, that's for sure.

"I think the guys will be working on it, trying to work out what's going on tonight and go from there."

Despite the shortened run, Webber finished the night fourth fastest, behind McLaren's Lewis Hamilton and Jenson Button, who both dominated the first free practice session earlier in the day.

Adding to Webber's worries was a sparking issue, after a piece of his car's floor appeared break off and scrape the tarmac.

Vettel had a similar problem in the closing stages of the India race but Webber said it was not a big deal.

Overall, Webber said the car generally felt "ok".

"Normally I struggle around carpark sort of race tracks, but I'll do my best to push as hard as possible around all the second-gear corners that are here this weekend," he said.

Meanwhile fellow Australian Daniel Ricciardo outpaced his Toro Rosso teammate in both of Friday's practice runs, finishing one spot ahead of him in 17th place.

Qualifying for Sunday's twilight race begins at midnight (AEDT) Saturday.