Guardian 4389 Repair Manual page 107

DC CONTROL
close and 12 volts DC is delivered to Wire 14 and to a
fuel solenoid. The solenoid energizes open to allow
fuel flow to the engine. This test will determine if the
circuit board is working properly.
PROCEDURE:
1. Set the AUTO-OFF-MANUAL switch to OFF.
2. Connect the positive (+) test lead of a DC voltmeter (or
VOM) into Pin 7 (Wire 14) of the circuit board connector
J1. Connect the common (-) test lead to frame ground.
3. While observing the meter, set the AUTO-OFF-MANUAL
switch to MANUAL.
a. The circuit board's crank and run relays should
energize and the engine should crank and start.
b. The meter should indicate battery voltage.
c. If battery voltage is indicated, proceed to Step 4.
If battery voltage is NOT indicated, proceed to
Test 53 results.
4. Disconnect Wire 14 at the Fuel Solenoid (FS).
a. Connect the positive (+) test lead to Wire 14.
Connect the negative test lead to a clean frame
ground. Set the AUTO-OFF-MANUAL switch to
MANUAL. Battery voltage should be measured.
If battery voltage is indicated, proceed to Step 5.
b. Connect the positive (+) test lead to Wire 14 at
the 4-tab terminal block in the control panel, see
Figure 17. Connect the negative (-) test lead to
frame ground. While observing the meter, set
the AUTO-OFF-MANUAL switch to MANUAL.
Battery voltage should be measured.
Figure 17. 4-Tab Terminal Block
5. Set the VOM to it's "R x 1" scale.
6. Disconnect Wire 0 from the Fuel Solenoid (FS). Connect
one test lead to Wire 0 and the other test lead to a clean
frame ground. CONTINUITY should be measured.
RESULTS:
1. If the engine cranks but does not start and battery volt-
age was NOT measured in Step 3, replace the circuit
board.
2. If the engine cranks and battery voltage was measured
in Step 3, but there was no battery voltage in Step 4a,
PART 4
repair or replace Wire 14 between 4-tab terminal block
and the Fuel Solenoid (FS).
3. If the engine cranks and battery voltage was measured
in Step 3 and no battery voltage is measured in Step 4b,
repair or replace Wire 14 between the J1 connector on
the circuit board and the 4-tab terminal block.
4. If the engine cranks but does not start and battery volt-
age was measured in Steps 2, 3 and 4, and CONTINU-
ITY was NOT measured in Step 6, repair or replace
Wire 0 between the Control Panel ground connection
and the Fuel Solenoid terminal. If CONTINUITY was
measured in Step 6, proceed to Test 52 or test 54
depending on the model.
TEST 54 - CHECK FUEL SOLENOID
DISCUSSION:
In Test 53, if battery voltage was delivered to Wire 14,
the fuel solenoid should have energized open. This test
will verify whether or not the fuel solenoid is operating.
Fuel Solenoid Nominal Resistance 27-33 ohms.
FUEL REGULATOR
Figure 18. The Fuel Solenoid (FS)
PROCEDURE:
1. Disconnect Wire 56 from the starter contactor relay
(SCR). This will disable the unit from cranking. For sin-
gle cylinder units, disconnect from the starter contactor
(SC) and isolate it from ground.
2. Place one hand on the Fuel Solenoid (FS). Cycle the
AUTO-OFF-MANUAL switch from MANUAL to OFF. You
should be able to feel the solenoid actuate as well as
hear it actuate. If a small screwdriver is placed on the
solenoid and then gently pulled away, a magnetic field
should be felt.
SECTION 4.4
DIAGNOSTIC TESTS
FUEL
SOLENOID
Page 105