Recommended Procedure (Econoline)
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2003 Ford RV Cutaway, 2003 Ford Pickup, 2003 Ford F550 Super Duty, 2003 Ford F450 Super Duty, and 2003 Ford Excursion. However, it is still accessible from the selected car via links, so may be relevant.
If necessary, remove generator and bracket to access pipe plug. Remove 1/8" pipe plug from top front of right cylinder head. See Figure. Install fuel pressure gauge. Start engine. Check fuel pressure with a full load on engine. DO NOT brake torque engine for more than 10 seconds. If fuel pressure is 45-80 psi (310-552 kPa), fuel pressure is okay. If fuel pressure is not 45-80 psi (310-552 kPa), replace right fuel check valve. Check valve is located in rear of right cylinder head between fuel inlet line and cylinder head.