Two of the most import diagnostic checks, when dealing with a driveability problem involve the ignition and the fuel systems. The questions most technicians attempt to answer first are "is there spark?'' and "is there fuel?'' This often leads to solving most basic problems. For ignition system diagnostic testing, please refer to the information on engine electrical components and ignition systems found earlier in this manual. If the ignition system checks out (there is spark), then you must determine if the fuel system is operating properly (is there fuel?).