I am a new and inexprienced owner of a Euro car, 94 SAAB 9000 CD auto and the fuel pump is playing up. The car has done close to 160,000k's and now it wont start unless I bash the fuel tank with a rubber mallet. Whats involved in replacing the internal pump and is there an external pump as well? Is an after market pump reliable and what type should I shop around for that is reliable and ecconomical. Please help.