On the game-winner, Carter was sprung by a leading pass from Marek Zidlicky, and he snapped a shot that eluded Halak.
Ovechkin opened the scoring 10:12 into the game with his 49th of the season. The sequence began with New Jersey defenseman Mark Fayne committing a defensive zone turnover. Nicklas Backstrom found the loose puck and moved it to Mikhail Grabovski, who passed it to Ovechkin for the quick shot.
The goal was Ovechkin's first even-strength point since Feb. 27.
That was all the Capitals would get, as Schneider turned them away at every opportunity.
Schneider stuffed Jason Chimera on a breakaway with 1:28 left in the first, and kept the puck out of the net during a second period flurry in which Julien Brouillette and Backstrom had chances from along the crease.
Ruutu drew New Jersey even with 7:39 left in the second with a redirection of Eric Gelinas' point shot. The goal was Ruutu's eighth of the season, and his third with the Devils following the March 5 trade from the Carolina Hurricanes.
Both the New Jersey and Washington power-play units were ineffective. The Devils were 0 for 5 and Washington finished 0 for 3.
New Jersey lost Patrik Elias in the first period after he was ridden into a stanchion by Washington's Tom Wilson. Elias, New Jersey's second-leading scorer with 51 points, skated seven shifts totaling 3:36.
Both teams have five games remaining this season, and essentially need to win out and hope Eastern Conference wild card-leading Detroit and Columbus and ninth-place Toronto lose their remaining games.
NOTES: Washington called up D Tyson Strachan from Hershey of the AHL on Friday morning. Strachan entered the game with 24 penalty minutes in 12 NHL games this season, and 56 penalty minutes in 57 AHL games. ... New Jersey scratched Stephen Gionta, Steve Bernier, Tim Sestito, Bryce Salvador, Ryane Clowe and Jon Merril. John Erskine, Jack Hillen, Patrick Wey and Connor Carrick were the Capitals' scratches. ... The Washington chapter of the Professional Hockey Writers Association announced right wing Joel Ward was their nominee for the Bill Masterton Trophy, awarded to the ''player who best exemplifies the qualities of perseverance, sportsmanship and dedication to hockey.''