Fuel Pump Pressure & Delivery Volume

Disconnect wiring at inertia switch, which is located behind trim panel in right rear side of cargo area on Sable and Taurus station wagons. Inertia switch is located behind trim panel on left side of trunk on all other models. Crank engine for at least 15 seconds to reduce system fuel pressure.
On Sable and Taurus models, disconnect fuel supply line at throttle body. Install In-Line Adapter (T85L-9974-B) and Fuel Pressure Gauge (D80L-9974-A) on throttle body. Reconnect inertia switch and start engine. Check fuel pressure at idle and then accelerate engine. Pressure should remain stable through entire period of acceleration.
If gauge readings are correct, disconnect inertia switch. Crank engine for 15 seconds to reduce fuel pressure. Remove gauge and in-line adapter. Install original fuel line and connect inertia switch. Start engine and check for fuel leaks.
On Tempo and Topaz models, disconnect fuel return line at throttle body. Try to avoid spilling any fuel. Run short hose from throttle body return port to a one quart calibrated container. Place fuel pressure gauge in-line between throttle body and fuel filter. Reconnect inertia switch.
Remove fuel pump relay, which is located on left side of dashboard near ECA. Replace relay with modified fuel pump relay. Run long lead, which is connected to terminal No. 1, to outside of vehicle where it will be available for grounding of relay.
Ground long lead from relay for 10 seconds to activate fuel pump. Check fuel system pressure while fuel pump is activated. If there is no pressure reading, check for voltage to fuel pump. Repair wiring if necessary.
If fuel pressure reaches 13-16 psi (.9-1.1 kg/cm² ) with minimum delivery volume of 6 oz. (18 cc) in 10 seconds, fuel pump is operating properly. Residual fuel pressure must remain above minimum of 11.6 psi (.8 kg/cm² ) immediately after shutdown.
If all 3 readings are correct, check for engine or electrical problems. If pressure is correct with low delivery volume, check for blocked filters and restricted supply lines. Correct any restrictions and repeat pressure test. If delivery volume is still too low, replace fuel pump/sender assembly.
If both pressure and flow conditions are met, but residual pressure does not hold after pump is turned off, check for leaking injectors or pressure regulator. If both check okay, replace fuel pump/sender assembly. If no flow or pressure is seen, fuel system should be rechecked for blockages.
If no blockage is found, remove fuel tank and replace fuel pump sender assembly. After completing test procedure, replace modified relay with original relay. Disconnect electrical connection to inertia switch. Crank engine 15 seconds. Remove gauge. Reinstall original fuel line. Reconnect inertia switch. Crank engine and check for leaks.