"Little things are happening; hopefully, they'll come together and make one big thing," said Capitals coach Terry Murray.
Dino Ciccarelli ignited the surge with the 400th goal of his career, becoming the 33rd player in National Hockey League history to reach that plateau.
Ciccarelli scored from the slot after grabbing a loose puck off a wrist shot by Dale Hatcher 5 minutes, 5 seconds into the third period.
It was the Capitals' smallest crowd of the season, but those on hand saw a large rally by a team that hasn't been tearing up the NHL lately.
Washington was 3-6-1 in its past 10 games before taking on a last-place Vancouver team that is having even more problems (1-9-2 in its past 12).
When the Canucks gained a 3-1 lead at 1:58 of the third period on a goal by Petr Nedved, it looked as if the Capitals were on the verge of an embarrassing loss. But Ciccarelli pulled off another of his key goals that almost always seem to spark Washington.
His goal cut the Vancouver lead to 3-2, and, less than five minutes later, Al Iafrate tied the score at 3 with a short-handed goal. It was the second short-handed goal of the night for Washington.
The Caps continued to roll, scoring a power-play goal for a 4-3 lead when Dale Hunter deflected in a wrist shot by Calle Johansson at 13:32.
Vancouver pulled goaltender Kirk McLean for an extra skater at 19:28 of the period, but Washington answered with an open-net goal by Mike Ridley with 23 seconds left.
Murray said of the Capitals' lapses before last night: "You try to figure out why it happens and put a finger on what you need to do to change it. I think sometimes we really get behind the eight-ball and put pressure on ourselves."
Washington followed that pattern again, but was able to rally.
"When the determination comes out, the pride comes out and we start to play really well," said Murray.