The entrance to Fire Canyon is on top of the cliffs behind farmer Zeb's house. Climb to the top of the cliffs and meet Keira after you collect enough power cells (at least 20). She is by the Zoomer's teleport gate.
Reach the End of the Canyon[edit]
Talk to Keira at the entrance of Fire Canyon. She will tell you that the Zoomer's heat shield will hold up until 500 degrees, but after that you explode. She tells you to hit blue cooling balloons that are spread out to keep the Zoomer cool. Hop on the Zoomer when you are ready to go to Rock Village. When driving the Zoomer try to stay in the cooler parts of the canyon, which are the darker parts of the lava. If you can, hit Lurkers to gain some air to keep the Zoomer cool, along with hitting the cooling balloons.
Follow the canyon from beginning to end to get the power cell at the end of the canyon. This power cell is impossible to miss so don't worry about it too much.