I think your mechanic is not knowledgeable enough to do the job.
There is a fuel pumps relay, I would check that. There is also fuse 13, a 30 amp fuse I would check. The relay gets it's power and ground from a LH Control Unit. If no power and ground to the relay, and the all wires are good, I would suspect the LH Control Unit. Do not use a test light to check for power and ground from the LH Control Unit, use of a test light may damage it. Use a High impedance DVOM.
There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online
There is a professional service called Identafix. http://www.identifix.com/info/about_us.htm They only deal with professional repair shops. They are in the Minnesota 651-633-8007 begin_of_the_skype_highlighting 651-633-8007 end_of_the_skype_highlighting. Your auto repair shop do all their diagnosis tests, and discuss your problem with a team of professional technicians great service cheap and very bright people. If the repair shop that are repairing your car are stumped this is a great service. This company only deal with automotive repair shops and don't answer questions for the general public but are an amazing knowledge base.