Section 1.11 - General Troubleshooting Guidelines; Introduction; Recommended Tools; Troubleshooting Reminders And Tips - Generac Power Systems 7 kW NG Repair Manual

Section 1.11
General Troubleshooting Guidelines

INTRODUCTION

This section familiarizes the service technician with the
manufacturer recommended procedures for the testing and
evaluation of various problems that can occur on the standby
generators with air-cooled engines. It is highly recommended
that you read these introductory tips before you attempt to
troubleshoot any of the three main generator components:
AC Generator, Air Cooled Engine, Transfer Switch.
Troubleshooting Flow Charts provide the simplest, quickest,
systematic means to troubleshoot the typical problems that
might occur during the lifetime of the unit. If you use the flow
charts and perform the indicated tests, you will be able to
identify the faulty component, which can then be repaired or
replaced as necessary.
The test procedures in each section do require a basic
knowledge of electricity and electrical safety, hand tool skills,
and use of Volt-Ohm-Meters.

RECOMMENDED TOOLS

In addition to the normal hand tools required, some test
procedures may require the use of specialized test equipment.
At a minimum you must have a meter that measures AC
voltage and frequency, DC voltage and current, and has the
ability to record Minimum / Maximum values (digital multi
meters [DMM] are recommended); standard meter test leads,
a set of piercing probe leads , and a set of pin probe leads for
the AMP connector pins. The manufacturer carries a set of
acceptable piercing probes (PN 0G7172), or other suppliers
piercing probes may be used. Fluke provides a high quality
piercing probe, PN AC89, which is highly recommended. The
manufacturer also carries a set of flexible pin leads for use with
the AMP connector plugs (PN 0J09460SRV).
For engine troubleshooting you will need a good manometer
which measures low pressure in Inches of Water Column (IN
W.C or IN H20). An ignition spark tester is also a handy tool to
have when working with air-cooled engines.
Testing and troubleshooting methods covered in each section
are not exhaustive. No attempt has been made to discuss,
evaluate and advise the home standby service trade of all
conceivable ways in which service and trouble diagnosis must
be performed. Accordingly, anyone who uses a test method
not recommended herein must first satisfy himself that the
procedure or method he has selected will jeopardize neither
his nor the products safety, and will not cause damage to any
connectors or components.

TROUBLESHOOTING REMINDERS AND TIPS

The most important step in troubleshooting is identifying the
actual problem. Use the History capability of the Nexus panel
to help you identify what the panel is seeing. Use the Alarm Log
to view the faults that caused the Warning or Alarm Shutdown.
The date-time stamp provides the date and time (to the second)
that the alarm event occurred. If there are several alarms that
all have the same date-time stamps, go to the first in the series
of alarms for that time. Some failures can cause a cascading
series of faults to occur, one right after the other. Compare the
Alarm Log and the Run Log to each other to see the operational
sequence of events.
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For instance: If the unit shut down on ALARM - Low Oil
Pressure, look to see what time it started. If it started at
8/20/10 14:27:30 (2:27 pm), and shut down on low oil
pressure on 8/30/10 10:15:22 (10:15 am), then the most likely
cause of the loss of oil pressure was low oil level. The unit
ran, providing power, for 10 days straight (approximately 234
hours). This would be validated by simply checking the oil level
of the unit. These are air-cooled 4 cycle engines and will use
The
oil while running. If run for extended periods of time (several
weeks for instance) they will require periodic shut-down to
check oil level and do a general inspection. Just think of leaving
your lawn mower running at full RPM for several weeks; what
would it do?
The next step is to determine the applicable flow chart to use
to help diagnose the problem. Use the flow chart index for the
part of the generator you are working with. If it is problem with
voltage, use Section 2 – AC Generators; for engine problems
use Section 4 – Engine/DC Control; for a problem with the
transfer switch, use Section 3 – Transfer Switch. The index for
each will help you clarify the problem and the flow chart to use.
In each flow chart start at the top and use the test indicated to
verify whether a component or control item is working properly
or not. At the end of each test follow the "good" or "bad"
arrows and perform the next test.
It is always good practice to continue to ask questions during
the troubleshooting process. When evaluating a problem, these
questions may help identify the problem quicker.
• What is it doing? (low voltage; not cranking; not transferring;
etc)
• What should it do? (run and start; transfer; shutdown; etc)
• Does the same thing happen each time?
• When is it happening?
• What could or would cause this?
• What type of test will either prove or disprove the cause of
the fault?
IMPORTANT NOTE CONCERNING
A number of the tests require the use of a volt-meter and a set
of wire piercing probes. When using the piercing probes make
sure you use some liquid tape or silicone to coat the insulation
where you pierced it; this will keep moisture out and prevent
long term corrosion.
It is very easy to damage the female pins in the connectors
on the control panel (AMP connectors) and the C1 connector
(Molex connector) which goes to the alternator can.
DO NOT ATTEMPT TO PUSH PROBE TIPS INTO THE FEMALE
PINS OF ANY AMP or MOLEX CONNECTORS; doing so will
damage the female pin which will create another problem.
Use the piercing probes on the correct wire to check for the
appropriate voltages ; or use the flexible pin leads, available
from the manufacturer (PN 0J09460SRV) to work with the AMP
connector plugs.
PART 1
GENERAL INFORMATION
CONNECTORS