18NA361

Bulletin No.:
Service Bulletin
Date:
18-NA-361
October, 2019
TECHNICAL
Subject:
Brand:
Chevrolet
GMC
Diagnostic Tip for Fuel System Contamination
Model:
Model Year:
VIN:
to
Silverado
2017
2018
L5P
Silverado
1500
2020
2020
LM2
Silverado
2500/3500
2019
2020
L5P
Silverado
4500HD,
5500HD and
6500HD
2019
2020
L5D
Sierra
2017
2018
L5P
Sierra 1500
2020
2020
LM2
Sierra
2500/3500
2019
2020
L5P
Involved Region or Country
Copyright 2019 General Motors LLC. All Rights Reserved.
North America, Israel
from
Engine:
from
to
Transmission:
Page 2
October, 2019
Bulletin No.: 18-NA-361
Condition
5168457
Some technicians may find metal particles in the fuel system during diagnostics.
Important: If the fuel/water filter has been removed for inspection. Do Not install the
filter back into the housing until the fuel/water separator reservoir has been cleaned.
Refer to Information on Fuel/Water Filter Removal section below.
Correction
If you encounter such a situation. DO NOT replace the fuel system as described in
16-NA-102.
Please perform the following fuel system flushing procedure prior to performing further
diagnostics
Once the fuel system has been flushed, continue with diagnostics as described in SI.
Bulletin No.: 18-NA-361
October, 2019
Page 3
Information on Fuel/Water Filter
Removal
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5417311
Water or other like contaminates in the fuel will create
drivability concerns and loss of engine power. If water
and/or debris is present in the fuel system, the fuel
cannot cool and lubricate the components properly,
causing overheating, rust and corrosion. This can result
in component failure. Water and debris can enter the
fuel system in several ways, either through a
contaminated refueling source, plugged venting or
through long term condensation in the vehicle fuel
tanks.
1. Remove the fuel/water filter from the housing using
care not to separate the filter from the fuel/water
separator reservoir.
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October, 2019
5417298
2. Use care, separate the filter from the fuel/water
separator reservoir by placing the filter downwards
in a clean/dry drain pan.
Bulletin No.: 18-NA-361
5417283
– If the filter is facing upwards, debris left on the
sides of the filter may escape past the O-ring
seal during removal and settle in the fuel/water
separator reservoir.
– Water and/or debris left in the fuel/water
separator reservoir will flow past the filter, directly
in to the fuel system when re-started.
3. Inspect the fuel/water separator reservoir and filter
for heavy debris.
• If heavy debris is found in the filter, clean the
fuel/water separator reservoir and continue to
the Fuel System Flushing Procedure.
• If no signs of debris are found, clean the fuel/
water separator reservoir, install new filter and
refer to SI for further diagnostics.
Bulletin No.: 18-NA-361
October, 2019
Fuel System Flushing Procedure
Note: Performing the test may aid in determining the
source and section of the fuel system causing the
contamination.
Page 5
7. Install a clear line between the fuel supply hose
and the fuel return hose.
8. Run the fuel pump until the fuel runs clear in
the line.
1. If removed, re-install the fuel filter.
5168447
5167517
2. Disconnect the chassis side fuel feed hose (3) from
the engine side fuel feed pipe (4).
3. Place the end of the chassis side fuel feed hose
into a clean container and run the fuel pump to
clean any debris left in the fuel lines, approximately
2-3 gallons (7.6 –11.4L).
4. Clean the fuel/water separator reservoir.
5. Install new fuel filter.
6. Disconnect the chassis side fuel return hose (2)
from the engine side return pipe (1).
Note: The white “Tubing” shown in the graphics below
depict the route of the clear line, not the length.
5168476
9. Connect the fuel supply hose to the engine
supply pipe.
10. Install a clear line in series at the fuel return hose
to the engine return pipe.
11. Run the fuel pump until the fuel runs clear in
the line.
Reconnect all fuel lines and retest for any codes or
symptoms in the vehicle.
Parts Information
No parts are required for this repair.
Page 6
October, 2019
Bulletin No.: 18-NA-361
Version
5
Modified
Released December 10, 2018
Revised June 24, 2019 - Added 2020 to Model Year.
Revised August 14, 2019 – Added 2019 and 2020 Silverado HD Models
Revised October 03, 2019 - Added Information on Fuel/Water Filter Removal section.
Revised October 14, 2019 - Removed LCF and added 2020 Silverado/Sierra 1500
with LM2.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.
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