Four-cylinder engine (except 1991 models)
1. The CFI fuel injection unit is equipped with either fork-type connectors (used on earlier models) or spring-lock type connectors (used on later CFI models). In either case, you will need an adapter to install the pressure sensor between the fuel delivery line and the injection unit (see illustration).
2. Relieve the pressure in the fuel system (see section 2).
3. Disconnect the fork-type connector or spring-lock connector and separate the supply line (it is larger) from the charging unit (see section 3).
4. Using an adapter, install the pressure sensor between the disconnected fuel supply pipe and the injection unit pipe.
5. Turn on the inertia switch (see section 2).
6. Start the engine, check the fuel pressure in the system at idle and compare with the value specified in the specification. Increase the speed, the pressure should be constant regardless of the engine speed.
7. If the indicator shows a pressure value higher than the permissible value, it means that either the pressure regulator is clogged (see section 11), or the fuel return line is clogged.
8. If the pressure value is lower than the permissible value, then the fuel pump is faulty (see section 4), the nozzle is leaking (see section 12), the fuel supply line is blocked, or there are leaks somewhere on the fuel supply or return lines (see section 3).
9. Relieve the pressure in the fuel system again, remove the sensor, connect the supply line to the fuel recharging unit.
10. Turn on the inertia switch, start the engine, check for leaks.
1991 4-cylinder engines and all V6 engines
11. It is easy and quick to measure the fuel pressure in the system using the Ford T80L - 9974 - B (or similar) pressure sensor and the T85L - 9974 - A (or similar) adapter. V6 engines with CFI systems are equipped with Schrader valves. Therefore, there is no need to disconnect the fuel lines to read the sensor readings.
12. Ford's special kit for resetting/measuring fuel pressure consists of a sensor unit and an adapter complete with a Schrader valve. If you have such a sensor, you can use this method as an alternative to the one described in section 2.
Warning: Do not attempt to relieve pressure through the Schrader valve without a special tool.
13. To connect the sensor, simply remove the valve cover, screw on the adapter, then connect the sensor to the adapter.
14. Start the engine and allow it to idle at a constant speed. Note the fuel pressure reading and compare it to the specification.
15. If the pressure value is lower than the specification, there may be a leak in the fuel line, a faulty pump, or a leak in the injector.
16. When the pressure values are higher than normal, the cause may be a blocked fuel line or fuel pressure regulator. See the relevant section on the fuel injection system.
(The article was taken in its entirety from the specified website FORDBOOK.ru)