Generac Power Systems NP-40G - Manual (Page 109)

Section 7.2- ENGINE DC CONTROL SYSTEM
Test 4- Check Battery/Battery Cir­
cuit
DISCUSSION:
The battery circuit includes the red battery cable
that extends from the units 12 volt battery to the
Starter Contactor. The circuit also includes Wire 13
(RED) from the Starter Contactor to the 15 amp
Fuse. It includes one Wire 15 from the Fuse to the
Primer Switch and a Wire 15 from the Fuse to the
Engine Controller circuit board.
TEST PROCEDURE:
Inspect the battery terminals and cables care­
fully. Clean cables and cable connections If neces­
sary. Replace any bad cable(s), including the bat­
tery negative cable, if necessary.
Check Wires 13 and 15 for an open or shorted
condition. Repair, reconnect or replace bad wire(s)
as necessary.
Use a battery hydrometer to test the battery for
“state of charge" and for “condition". Follow the
hydrometer manufacturer's instructions carefully.
If the hydrometer used does not have a “percentage
of charge" scale, use the following as a reference:
SPECinC GRAVITY PERCENTAGE OF CHARGE
1.260 100%
1.230 75%
1.200 50%
1.170 25%
RESULTS:
1. Repair, reconnect or replace any open or shorted
wire(s).
2. If necessary, recharge the battery to a 100% state
of charge. Disconnect the battery cables before
recharging the battery.
3. If (after recharging) the difference In specific
gravity between the highest and lowest reading
cells is greater than 0.050 (50 points) the battery is
nearing the end of its useful life and should be
replaced.
Test 5- Test Fuei Pump
Refer to Page 3.3-1.
Test 6- Test Primer Switch
DISCUSSION:
See Figure 2 on facing page. When this rocker
type switch Is held at "PRIME" position, fused bat­
tery voltage is delivered to the Fuel Pump to prime
the carburetor.
With the switch set to "OFF", battery voltage is
delivered to the Fuel Pump from the Engine Con­
troller board during cranking and running (via Wire
14).
TEST PROCEDURE:
1. Disconnect Wires 15,14 and 14A from the switch
terminal to prevent interaction.
2. Set a VOM to Its “Rxl" scale and zero the meter.
3. Connect the VOM test leads across the Wire 15
terminal and the Wire 14A terminal. The meter
should read "infinity". Set the switch to "ON" or
"PRIME" and the meter should Indicate "continu­
ity".
4. Connect the VOM test leads across the Wires 14
and 14A terminals. The meter should read "conti­
nuity". Set the switch to "ON" or "PRIME" and the
VOM should read "infinity".
RESULTS:
1. Replace switch if it fails the test.
2. If the switch is good, go to Test 7.
Test 7- Check Wire 14A to Fuei
Pump
DISCUSSION:
If no power was available to the Fuel Pump in
Test 3, either the Primer Switch is defective or Wire
14A is open.
TEST PROCEDURE:
Inspect Wire 14A between the fuel pump and
primer switch for proper connections. Check for
open condition with a VOM.
RESULTS:
Repair, reconnect or replace Wire 14A as neces­
sary.
Test 8- Check Power Suppiy to
Starter Motor
DISCUSSION:
When the Start-Run-Stop switch is set to
"START", Wire 17 Is connected to ground. Engine
Controller circuit board action then delivers a DC
voltage to the Starter Contactor coil and the
Contactor’s normally-open contacts close. On clo­
sure of the contacts, battery power is delivered
directly to the Starter Motor to crank the engine.
This test will determine if battery voltage Is avail­
able to the Starter Motor for cranking the engine.
TEST PROCEDURE:
1. Set a VOM to read battery voltage (12 VDC).
2. Connect the meter test leads across the starter
terminal and frame ground.
3. Hold the Start-Run-Stop switch at "START". The
VOM should read battery voltage and the engine
should crank.
Page 7.2-7