Martin Biron had 23 saves as the Flyers ended a skid that tied their longest victory drought at the start of the season. They also were winless in their first six games in 1999-00, posting an 0-4-1-1 mark before also winning in the seventh game.
Zach Parise had a goal and set up scores by Dainius Zubrus and Travis Zajac for New Jersey. Martin Brodeur, who came into the game with a 5-1 record, a 1.30 goals against average and .942 save percentage, faced 28 shots in taking the loss.
The Flyers' win came just hours after they learned that star center Daniel Briere would be sidelined up to a month with a torn abdominal muscle that will have to be surgically repaired.
Richards more than made up for his absence with a spectacular performance. The Flyers captain iced the game midway through the third period by skating down the left wing and centering a perfect cross-ice pass Lupul re-directed past Brodeur for a 5-3 lead.
Hartnell scored into an empty net with less than two minutes to play.
The lead changed three times in the first two periods, with Richards setting up goals by Gagne and Hartnell in the final 10 minutes of the second period to give the Flyers the lead for good.
Gagne tied that game at 3-all, scoring in front after Knuble tipped Richards' shot from the left circle.
Richards did all the work on Hartnell's goal, skating behind the net and firing a shot at Brodeur. Hartnell outmuscled two Devils to put in the rebound.
New Jersey scored in the opening and closing minute of the first period in taking a 3-2 lead.
Zajac got his first of the season by banking a shot off Flyers defenseman Braydon Coburn 47 seconds after the opening faceoff.
Carter tied the game just over a minute later with a great shot from the right circle after skating up the ice with a breakout pass by Biron.
Knuble got his first goal, breaking in from the right circle at 11:25 with Devils rookie Pierre-Luc Letourneau-Leblond serving a five-minute penalty for boarding. Richards gave him the pass that set up his run at Brodeur.
Zubrus tied the game less than four minutes later, scoring alone in front on a power play.
Parise stuffed a rebound past Biron with 19 seconds left in the period.
Notes: Gagne was back in the lineup after missing Wednesday's game with the flu. ... Riley Cote got the best of Letourneau-Leblond in a second-period fight. ... With Briere out of the lineup, the Flyers dressed Darroll Powe.
