2 circuits operate the solenoid. The following is from my '98 manual:
"FUEL SHUTDOWN SOLENOID TEST
NOTE: The fuel shutdown (shut-off) solenoid
and fuel shutdown solenoid relay are
not controlled by the powertrain control module
(PCM).
(1) With the ignition switch off, the solenoid shaft
should be down and the injection pump lever should
be in the shutdown position (no fuel supply to injection
pump).
(2) Turn the ignition switch to the CRANK (starter
engage) position and observe the solenoid shaft and
injection pump lever. The shaft should pull up (shaft
retracted into the solenoid) and the pump lever
should be in the run position (fuel being supplied to
injection pump).
(3) Release the ignition key from the CRANK to
the ON position. The shaft should remain in the up
position and the pump lever should remain in the
run position (fuel being supplied to injection pump).
If the solenoid shaft is not moving, refer to
the following:
(4) Disconnect the solenoid three-wire pigtail wire
harness from the main engine harness.
(5) If the solenoid shaft did not move up when the
ignition switch was in the CRANK position, check for
12 volts at the three-way connector. This will be the
circuit coming from the fuel shutdown solenoid relay.
Refer to Group 8W, for wire connector pin location
and circuit identification. If 12 volts is not present at
this circuit when the key is in the CRANK position,
check the fuel shutdown solenoid relay. Refer to
Relay Test—Fuel Heater/Fuel Shutdown Solenoid in
this section of the group. Also check the wiring
between the relay and the solenoid.
(6) If the solenoid shaft moves up when the ignition
switch is in the CRANK position, but moves
down when the key is released from the CRANK to
the ON position, check the circuit coming from the
ignition switch for 12 volts. Refer to Group 8W, for
wire connector pin location and circuit identification.
(7) If the shutdown solenoid is being replaced, its
shaft length must be adjusted. Refer to Fuel Shutdown
Solenoid Removal/Installation for procedures. "
Dan