FUEL SYSTEM

24-FL-001G

FEBRUARY 2024

MULTIPLE MODELS

TESTING FUEL QUALITY TO DIAGNOSE
ENGINE STARTABILITY / HESITATION / DRIVEABILITY ISSUES
Description: This bulletin outlines the basic components of the BG Fuel Test Kit and the procedure to
test the quality of the fuel during vehicle diagnosis.
Poor fuel quality may lead to cold engine startability issues, hesitation at idle or during acceleration,
and/or poor driveability. In addition, prolonged vehicle operation with poor quality fuel may result in
damage to the fuel system and formation of engine deposits.
The BG Fuel Test Kit can be used to determine the following aspects of the fuel:
•
•
•

Sediment / Water Contamination Inspection
Specific Gravity
Alcohol Content

Applicable Vehicles: All models equipped with gasoline engines.
SST Information:
Tool Name

Tool #

Figure

Remarks
BG Fuel Test Kit (P/N J-48983) is the
approved fuel quality testing tool to be
used during vehicle diagnosis.

BG Fuel Test Kit

J-48983

SST ordering information:
Bosch Automotive Service Solutions
Phone: 1.866.539.4248
Inquiries: [email protected]

NOTE: Kit contains the following components.
• TWO (2) Hydrometers (gasoline / diesel*)
o Do not use the diesel* hydrometer with
specific gravity range from 0.800 to 0.900.
o Use only the gasoline hydrometer with
specific gravity range from 0.700 to 0.800
for the correct measurement of the fuel to be
tested.
• Graduated cylinder (100ml)
• Graduated cylinder (alcohol test)
• Graduated cylinder small stopper
• Graduated cylinder holding fixtures
• Specific gravity vs. temperature reference chart

Circulate To: General Manager, Service Manager, Parts Manager, Warranty Manager, Service
Advisors, Technicians, Body Shop Manager, Fleet Repair

Warranty Information:
• When necessary, the use of the BG Fuel Test Kit may be a part of the normal diagnostic
troubleshooting process that may be covered under warranty.
• However, if the root cause of the vehicle condition is due to poor fuel quality, then some or all of
the parts and labor expenses may be subject to Customer Pay.
Service Procedure:
1.

Prepare the tall graduated cylinder attached to the
fixture base.
❖ Be sure that the inside of the cylinder is
clean and free of contaminants.

2.

Obtain sample fuel from the incident vehicle and fill
the graduated cylinder to the 100ml mark.
❖ There are several different methods
available to gather a small quantity of fuel
for testing.
❖ Follow the applicable Shop Manual
procedures and all precautions (fuel is
flammable) as required to perform any ONE
of the following methods, as feasible.
➢ Low Pressure Front Fuel Line Method: Refer
to Shop Manual section (Fuel Delivery
System > Fuel Line > Low Pressure Fuel
Line). Follow the published procedure to
temporarily disconnect the quick-connector
to capture the sample fuel.
➢ Under Vehicle Method: Lift the vehicle and
disconnect the large fuel hose of the fuel
filler neck from the fuel tank inlet. Using a
long socket extension, lightly push open the
inlet check valve at the inlet of the tank and
capture the sample fuel.

3.

Visually inspect the collected fuel sample for
presence of sediment, debris, or water
contamination. (Example shown at right. Replace
fuel if contamination is found.)

4.

Insert the thermometer into the graduated cylinder
and attach the clip to the top rim.

5.

Wait a few minutes to allow for the temperature to
stabilize, then record the measured temperature of
the gasoline sample. Remove the thermometer
afterwards.

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6.

Insert the gasoline hydrometer with specific gravity range from 0.700 to 0.800 into the graduated
cylinder and wait until it stabilizes while floating in the fuel. Read the number at the liquid line
on the side of the hydrometer for the specific gravity measurement.

7.

Refer to the supplied reference chart to look up the measured temperature and the hydrometer
reading to find the corresponding specific gravity. (Examples below)

NOTE: The fuel tanks of vehicles having contaminated fuel or fuel outside the NORMAL specific
gravity range should be drained and refilled.
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8.

Prepare the small graduated cylinder for fuel alcohol content testing.
❖ Be sure that the inside of the cylinder is clean and free of contaminants.

9.

With the stopper cap removed, add clean water up
to the (A) water fill line.

10. Add fuel from the tall graduated cylinder to the
(B) fuel fill line.
11. Insert the stopper cap at the top to seal it and
vigorously shake the contents for at least 10
seconds or more.
12. Let the mixture settle for approximately 5~10
minutes.
❖ At this point, any alcohol of the sample will
combine with water and begin to separate
from the fuel.
13. Read the line where it separates and find the
corresponding (D) alcohol % level of the fuel
sample.
NOTE: High alcohol content in the fuel can cause
lean codes and other engine startability and
driveability conditions.
14. After completing the fuel tests, prepare the Fuel Test Kit for storage.
• Rinse all pieces with window cleaner and water, then towel dry thoroughly.
• Store the reference chart behind the protection foam.
• Arrange all the components so that they are protected by the clamshell storage case.

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