What is the difference between a fuel pump for a 15 gallon tank and the pump for a 19 gallon tank

4 gallons!!!!..have you ever filled it up when it was close to empty and looked at the gas pump to see how many gallons it held? there are 3 different models,Sahara 4.0L....Sport 4.0L...SEL 2.5L.... There are 2 different pumps,one for a 15 gallon tank,and one for a 19 gallon tank.same 2 pumps for all 3 models.the sender is the difference,the float/arm/switch. for instance>If somebody put in a new fuel pump, and used one for a 19 gallon tank, the sender would think full (15 gallons) is about 3/4 full.there is a part number stamped on your tank somewhere.gonna have to crawl under it or put it on a lift if you can drive it.odds are you have a 19 gallon tank.the stripped down models and the 2.5L 4 cylinders came with the 15 gallon tank.if you can't find a part number on the tank,then Go to (jeep.com) and send them an email with your VIN requesting a build sheet and they will email you back with everything your Jeep came equipped with from the factory.