A B737-300's fuel quantity system indicated that a dispatch fuel quantity of 13.8 was onboard during the originating preflight. On takeoff the fuel level dropped to about 7.0 prompting a return to land.

Narrative

During preflight checks of originator; discussion with Agent indicated Fuelers had over fueled aircraft to 13.8 (Release called for 11.2). Subsequently; he noted and I concurred that inbound fuel noted on fuel slip was 13.8; therefore FOB; no gallons added. During cockpit prep; PDC clearance was modified from filed route; and as is often the case; a lengthy discussion evolved to ensure that we were straight on what ATC really wanted us to do. Continuing with my setup; I did in fact PTT the fuel quantity (analog gauges); noting both needles drop and return to 7.1 and 6.7 respectively. During Before Start Originating checklist; fuel was noted at '13.8; cleared with 11.2.' CDU also matched quantity. During Before Push checklist; fuel audit was confirmed; noting that zero gallons had been added. Upon takeoff; as pilot monitoring; my primary scan was inside; and at liftoff when pilot flying called for gear; my scan noticed both fuel quantity gauges drop to just below 3000# each; CDU alert message came on 'Insufficient Fuel;' and both FWD fuel pump low press lights came on. With a dash power takeoff; fairly low gross weight; 98 passengers; cool morning; the aircraft climbed very well; and I wasn't surprised to see the low press lights come on -- until they hadn't gone out until about two minutes later. Remembering the conversation with the Agent about fueling; I pulled out the logbook and confirmed inbound fuel from the previous day's flight was 7.8. Suspecting a fuel gauge(s) problem; we requested a return to the airport and landed uneventfully; shutting down at the gate with 5300 LBS. Company Mechanic on duty came at our request; wing tanks subsequently dipstick and current fuel quantity reading was confirmed. Although a complete fuel audit should have caught the problem (noting the inbound fuel of 7.8); the fuel quantity gauge problem was still present. The extra time spent dealing with the clearance issue was a detractor and could be alleviated if we received ONLY what ATC wants us to do instead of embedding it in what we were originally filed to do; and frequently done differently at different Stations.