The most common cause for this symptom is lack of fuel pressure. The first thing to do is measure the fuel pressure. It should be 55-60 psi engine running and 60-66 psi engine off key on. You can sometimes gain 3-6 psi just by replacing a clogged fuel filter. Above that you will need to replace the fuel pump itself which is located in the fuel tank. Remember to releave the fuel pressure before disconnecting the fuel lines.
Drain the fuel from the fuel sender assembly into an approved container in order to reduce the risk of fire and personal injury. Never store the fuel in an open container.
In order to reduce the risk of fire and personal injury that may result from a fuel leak, always replace the fuel sender gasket when reinstalling the fuel sender assembly.
The fuel pump strainer must be in a horizontal position when the sending unit is installed in the tank. When installing the sending unit, assure that the fuel pump strainer does not block full travel of the float arm.