Jabari Sandifer added 16 points, nine rebounds, seven assists and four steals for the Leathernecks, who are 3-0 for the first time since the 1989-90 season.
Western Illinois broke away from a 12-12 tie by running off 13-straight points, the last six from Fuller, capped by a dunk and led 39-24 at the half.
Tai Odiase had 16 points for the Flames and Dikembe Dixson and Paris Burns scored 11 apiece.
The Leathernecks forced 16 turnovers and held the Flames (0-2) to 25 percent shooting. Jalen Chapman had six of the Leathernecks' 11 blocked shots.
The game was a foul-fest with the teams combining for 50 fouls and 70 free throws. The Flames were 24 of 39 while Western Illinois went 19 of 31.