Alcohol/Contaminants-in-Fuel Diagnosis (LDD or LUJ)
Diagnostic Instructions
Test Description
Water contamination in the fuel system may cause driving
conditions such as hesitation, stalling, no start, or misfires in
one or more cylinders. Water may collect near a single fuel
injector at the lowest point in the fuel injection system and cause
a misfire in that cylinder. If the fuel system is contaminated with
water, inspect the fuel system components for rust or
deterioration.
Ethanol concentrations of greater than 10% can cause
driveability conditions and fuel system deterioration. Fuel with
more than 10% ethanol may result in driveability conditions such as
hesitation, lack of power, stalling, or no start. Excessive
concentrations of ethanol used in vehicles not designed for this
type of propellant may cause fuel system corrosion, deterioration
of rubber components, and fuel filter restriction.
Reference Information
Special Tools
CH 44175 Fuel Compression Tester
For equivalent regional tools, refer to
Special Tools .
System Verification
The fuel sample should be drawn from the bottom of the tank so
that any water present in the tank will be detected. The sample
should be bright and clear.
If the sample appears cloudy, or contaminated with water, as
indicated by a water layer at the bottom of the sample, perform the
particulate contaminants in fuel testing procedure. If alcohol
contamination is suspected, perform the alcohol in fuel testing
procedure.
System Testing
Alcohol in Fuel Testing with Special Tool
1. |
Test the fuel composition
using CH 44175 Fuel Compression Tester and
Instruction Manual. |
2. |
If water appears in the fuel
sample, clean the fuel system. |
3. |
Subtract 50 from the reading
on the DMM in order to obtain the percentage of alcohol in the fuel
sample. |
4. |
If the fuel sample contains
more than 15% ethanol, add fresh, regular gasoline to the vehicles
fuel tank . |
5. |
Test the fuel
composition. |
6. |
If testing shows the ethanol
percentage is still more than 15%, replace the fuel in the
vehicle. |
Alcohol in Fuel Testing without Special Tool
1. |
Using a 100 ml specified
cylinder with 1 ml graduation marks, fill the cylinder with fuel to
the 90 ml mark. |
2. |
Add 10 ml of water in order to
bring the total fluid volume to 100 ml and install a
stopper. |
3. |
Shake the cylinder vigorously
for 10-15 s. |
4. |
Carefully loosen the stopper
in order to release the pressure. |
5. |
Reinstall the stopper and
shake the cylinder vigorously again for 10-15 s. |
6. |
Put the cylinder on a level
surface for approximately 5 min in order to allow adequate liquid
separation. If alcohol is present in the fuel, the volume of the
lower layer, which may now contain both alcohol and water, will be
more than 10 ml. For example, if the volume of the lower layer is
increased to 15 ml, this indicates at least 5% alcohol in the fuel.
The actual amount of alcohol may be somewhat more because this
procedure does not extract all of the alcohol from the fuel.
|
Particulate Contaminants in Fuel Testing Procedure
1. |
Using an approved fuel
container, draw approximately 0.5 L of fuel. |
2. |
Place the container on a level
surface for approximately 5 min in order to allow for the
particulate contamination to settle. Particulate contamination will
show up in various shapes and colors. Sand will typically be
identified by white or light brown crystals. Rubber will appear as
black and irregular particles. |
3. |
Observe the fuel sample. If
any physical contaminants or water are present, clean the fuel
system. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
|