help, i have a 94 c220. once in awhile after the car sets it cranks but refuses to start. the time it sets doesnt really matter, it could be anywhere from a few minutes to days. could this be the fuel check valve or am i barking up the wrong tree? my son usually drives this car and he waits for the fuel pump to run awhile before he tries to crank it over. at least we think the noise in the back is the pump. he almost always has good luck with this method.