Fuel Quality

TM 9-2320-312-24-2

Testing and Adjusting Section

4. If fuel quality is still suspected as a possible

i01370330

cause to problems regarding engine

Fuel Quality - Test

performance, disconnect the fuel inlet line, and

temporarily operate the engine from a separate

SMCS Code: 1280-081

source of fuel that is known to be good. This

will determine if the problem is caused by fuel

This test checks for problems regarding fuel quality.

quality. If fuel quality is determined to be the

Refer to Diesel Fuels and Your Engine, SEBD0717

problem, drain the fuel system and replace the

for additional details.

fuel filters. Engine performance can be affected

by the following characteristics :

Use the following procedure to test for problems

regarding fuel quality:

Cetane number of the fuel

1. Determine if water and/or contaminants are

Air in the fuel

present in the fuel. Check the water separator (if

equipped). If a water separator is not present,

Other fuel characteristics

proceed to Step 2. Drain the water separator, if

necessary. A full fuel tank minimizes the potential

for overnight condensation.

i01823195

Fuel System - Prime

Note: A water separator can appear to be full of fuel

when the water separator is actually full of water.

SMCS Code: 1258-548

2. Determine if contaminants are present in the

fuel. Remove a sample of fuel from the bottom

of the fuel tank. Visually inspect the fuel sample

for contaminants. The color of the fuel is not

Fuel leaked or spilled onto hot surfaces or elec-

necessarily an indication of fuel quality. However,

trical components can cause a fire. To help pre-

fuel that is black, brown, and/or similar to sludge

vent possible injury, turn the start switch off when

can be an indication of the growth of bacteria or

changing fuel filters or water separator elements.

oil contamination. In cold temperatures, cloudy

Clean up fuel spills immediately.

fuel indicates that the fuel may not be suitable

for operating conditions. The following methods

If the engine's fuel system is run dry, fill the fuel

can be used to prevent wax from clogging the

tank. Then prime the fuel system in order to remove

fuel filter:

any air bubbles from the system.

Fuel heaters

NOTICE

Blending fuel with additives

Do not loosen fuel lines at the fuel manifold. The

engine components may be damaged and/or loss of

Utilizing fuel with a low cloud point such as

priming pressure may occur when the fuel lines are

kerosene

loosened.

Refer to Operation and Maintenance Manual,

"Fuel Recommendations" for more information.

3. Check fuel API with a 9U-7840 Fluid and Fuel

Calibration Gp for low power complaints. The

acceptable range of the fuel API is 30 to 45

when the API is measured at 15 C (60 F), but

there is a significant difference in energy within

this range. Refer to Tool Operating Manual,

NEHS0607 for API correction factors when a low

power problem is present and API is high.

Note: A correction factor that is greater than 1.000

may be the cause of low power and/or poor fuel

consumption.