FMVSS 301, “Fuel System Integrity”, limits the amount of spilled fuel in certain laboratory type crash tests. This paper will address one type of fuel leakage and flow that occurs in real-world type situations. This type of fuel flow is specifically called “fuel line siphoning”. Fuel line siphoning will be defined, as will its causes. The conditions necessary for siphoning to occur will be addressed, as well as the consequences of siphoning. Finally, fuel line siphoning countermeasures will be analyzed and illustrated.