BULLETIN NUMBER:
IB24-L-001

IMPORTANT SERVICE
INFORMATION FOR:
✓
SERVICE MANAGER
✓
SERVICE ADVISOR
✓
TECHNICIAN
✓
PARTS DEPARTMENT
✓
WARRANTY
PERSONNEL

ISSUE DATE:
AUGUST 2024
GROUP:
FUEL AND EXHAUST

GASOLINE CONTAMINATION
AFFECTED VEHICLES
•

2020.5MY to current Isuzu Vehicles equipped with:
6.6L gasoline engines
INFORMATION

Isuzu Dealership personnel should encourage Isuzu customers to follow the fuel system
information outlined in the FUEL section of their vehicle’s Owner’s Manual. Isuzu has
found many instances of gasoline contamination caused during the refueling process due
to incorrect substances entering the gas tank. Additionally, during refueling, it is possible
for water (and other contaminants) near the gasoline filler neck to enter the fuel tank along
with the gasoline. This can also occur if the surrounding area is dirty and/or a service
station does not regularly inspect and clean its storage tanks, or if a service station
receives contaminated gasoline from its supplier(s). Running an engine with gasoline
contamination may lead to damage to the fuel system and/or catastrophic engine damage.
Protect your customer’s engine from contaminated gasoline by recommending regular
fuel system inspection and maintenance. This will help ensure continued engine
performance of the Isuzu vehicle and provide the earliest detection of fuel contamination.
Maintenance is the customer’s responsibility. Discovering and correcting a contaminated
fuel issue early can substantially reduce the likelihood of damage to fuel system and
engine components.
Fuel contamination in the affected vehicles can be defined as the presence of diesel fuel,
ethanol, water, rust, poor quality fuel, or any other substance other than regular unleaded
gasoline with a posted octane rating of 87 or higher in the fuel system. It should meet
ASTMD4814 in the U.S. and CGSB 3.5-M87 in Canada. Operating a vehicle’s engine on
fuels and additives that do not meet the vehicle manufacturer’s specifications as outlined
in the Owner’s Manual for lubrication and cooling, or that have improper anti-corrosion
properties, can cause drivability problems as well as component damage or even failure.
NOTE: Any repairs needed as a result of using incorrect or contaminated fuels are
not warrantable.
Contamination of fuel system components may cause symptoms including, but not limited
to, the following:

•
•
•
•
•
•
•
•

Crank, but no start
Long crank/Hard start
Running rough
Low power
Fuel pressure-related DTCs
Fouled spark plugs
Excessive oil consumption
Unburned liquids dripping from the
exhaust system (not water from
condensation)

•
•
•
•
•
•
•
•

Loss of acceleration
Engine knocking or detonation
Exhaust smoke
Catalytic converter overheating
Fuel system slow to build pressure
Speed fluctuation
Engine seizing, broken pistons,
scored cylinders
Oil leaking, including possibly from the
rear main seal due to excessive
crankcase pressure

Most common sources of contamination:
•
•

Fueling errors (e.g., introducing diesel
into the fuel tank/s)
Above and below ground fuel storage
tanks

•
•

Fuel stored for long periods of time
Contaminated fuel source

NOTE: Some of these are difficult to identify in the shop and may require
external testing
Some examples of fuel contamination:
•
•
•

Water
Ethanol content more than 10% (E-15
and E-85) gasoline
Diesel fuel

•
•
•
•

Aged/Oxidized fuel
Unapproved fuel additives
Alternative fuels (unapproved for 6.6L)
Methanol content more than 5%

NOTE: If you are unable to identify the contaminant, it may be necessary to send
a sample of fuel out to a fuel analysis lab for contamination identification.
Examples of possible damage

Cylinder wall scoring due to gasoline
contamination

Piston damage due to gasoline
contamination

Broken piston skirt due to gasoline
contamination

Piston land broken due to gasoline
contamination

Piston head broken/missing pieces
due to gasoline contamination

Overheated catalytic converter due to
gasoline contamination

FUEL TANK INSPECTION

While certain contamination such as diesel fuel in gasoline is more difficult to identify,
other types of contamination may be found more easily with a simple visual inspection
of the inside of the fuel tank. Look for signs of water, rust, or other contamination that
may have entered the fuel system from an outside source.
SERVICE PROCEDURE
CONTAMINATION DIAGNOSIS CHART
Step
Action

Value(s)

Yes

No

See
photos in
Table 1

Go to
Step 2

Go to
Step 3

__

Go to
Procedure
A

Go to
Step 3

__

Go to
Procedure
B

Go to
Step 4

__

Go to
Diagnostic
Aides or
Symptoms
in the
applicable
Work
Shop
Manual
(WSM)

System
OK

Using the J-45004-1 fuel siphon hose,
obtain a fuel sample of approximately
50mL (1.7oz.) into a fuel sample container.
•
1

•
•

Feed siphon hose into, and down,
the fuel filler neck, into the gas
tank.
Allow the fuel sample to sit for
approximately 2 minutes.
Compare the sample to the photos
of contaminated fuel in Table 1
below.

Does the fuel appear to be contaminated?

2

Follow the recommended procedure based
on the appearance of the fuel as compared
to the photos in Table 1.
Was a sample found to contain DEF or
Ethanol?

3

Does the sample appear to be
contaminated by material, and/or smell like
anything other than gasoline, other than
DEF or Ethanol?
1. Clear any DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.

4

3. Start the engine.
Are there any DTCs or conditions that you
have not diagnosed?

TABLE 1
All bad samples in Table 1 are a 50/50 mixture.
Condition
Image

Good
Diesel

Bad

Procedure

Note

B

Gasoline and
Diesel fuel will not
separate and
visually there is
very little, to no,
difference.
Depending on the
percentage of
contamination
there may be a
diesel smell, if the
ratio (%) of diesel
to gasoline is high.
After shaking the
container,
mixtures with
50% and above
diesel fuel will
hold a layer of
bubbles on the
surface that will
not immediately
dissipate like
gasoline.
Gasoline and
Water will
separate, and the
sample will appear
cloudy.

Water

Good

Bad

B

Gasoline will float
on top, and the
gasoline smell will
be present.

Good

DEF

Bad
A

Gasoline and DEF
will separate but
DEF will be very
difficult to see as
there is very little,
to no difference in
color or a
separation line.
Perform DEF
Contamination
Check.

PROCEDURE A – DEF or ETHANOL (E-15 or E-85) CONTAMINATION
These fluids are very corrosive and require all components to be replaced.
IMPORTANT: To prevent contaminated fuel from re-entering the system, be
sure to remove all contaminated fuel from the fuel tank.
IMPORTANT: Be sure to properly dispose of contaminated fuel in accordance
with local laws and guidelines.
1. Clean the fuel system and replace all metal fuel system components. Refer to
the applicable WSM section “Fuel System Cleaning” for procedure.
• Fuel tank sender
• High pressure fuel
pump

•

Low pressure fuel lines

•

Fuel rail

•

High pressure fuel lines

•

Fuel injectors

•

Fuel tank

2. Fill fuel tank to ¼ full using clean, fresh, and good quality gasoline.
3. Start the engine.
• Run for 15 minutes. Check for engine leaks and abnormal noises. Repair
as necessary.
• If the engine does not start, perform the Fuel System Diagnosis test from
the applicable WSM. Re-attempt engine start.
4. Stop engine.
5. Clean any fuel spillage from engine.
6. Return to Step 4 of the Contamination Diagnosis Chart

PROCEDURE B - Organic, Rust, Water, Diesel Fuel Contamination
1. Clean the fuel system. Refer to applicable WSM section “Fuel System Cleaning”
for procedure.
2. Fill fuel tank to ¼ full using clean, fresh, and good quality gasoline.
3. Start the engine.
• Run for 15 minutes. Check for engine leaks and abnormal noises. Repair
as necessary.
• If the engine does not start, perform the Fuel System Diagnosis test from
the WSM. Re-attempt engine start.
• If internal damage to the engine is suspected, the use of an inspection
camera to view inside the engine can be helpful. It may also be necessary
to disassemble the engine to determine the extent of the damage.
4. Stop engine.
5. Clean any fuel spillage from engine.
6. Return to Step 4 of the Contamination Diagnosis Chart