THe check engine is on in a friend of mines car. It isnt flashing a code it just stays on. problem is you can fill up the gas tank and after 33 miles you only have a 1/4 left. I dont understand what would cause that except for leak but then again the engine light wouldnt come on. Car has to be running rich as hell to burn that much fuel that quick. any advice? Other then hat car runs fine.