Eriksen gave the Eagles the lead for good at 14-7 on his first TD run, a 2-yarder with 2:35 left in the first quarter, and capped the scoring on a 5-yard carry with 3:58 left in the third.
Shaq Vann led Eastern Michigan with 90 yards rushing and Eriksen added 37. Sergio Bailey II had five catches for 78 yards.
Hasaan Klugh had 114 yards passing and 101 yards rushing for the 49ers.
Brody Hoying interepted Klugh's second pass attempt of the game and returned it 35 yards to give EMU the early lead. The 49ers bounced back, going 73 yards in four plays to tie it with 8:03 left in the first quarter. Eastern Michigan's next drive ended with Eriksen's first touchdown.
GRAND VALLEY FALLS IN OPENER
Bart Williams completed 22 of 27 passes for 303 yards and three touchdowns but it wasn't enough as No. 2 Grand Valley was upset in its Division II season opener.
Nick Keizer hauled in six receptions for 118 yards and two scores and Brandon Bean added seven catches for 84 yards and a touchdown for Grand Valley, which jumped out to a 13-0 lead in the first quarter.
After Indianapolis scored 17 unanswered points to take a four-point lead, Grand Valley went back on top, 20-17, on Keizer's 10-yard touchdown catch with 7:11 remaining. But Indianapolis responded with a 7-play, 89-yard drive that was capped by a 51-yard rushing touchdown by Al McKeller with 3:43 to go.
Grand Valley's final drive ended in the red zone after Williams' intended pass for Keizer on fourth down was knocked down.