1. FUEL & AIR SYSTEMS
Diesel Fuel
ALL NEW
SAFETY ISSUE: Do not smoke or have an open flame in the area when working
around or refueling any vehicle.
TECH TIP: Air to Fuel Ratio: The Air-Fuel-Ratio (AFR) is the ratio of the
actual amount of air to the fuel used for internal combustion. The chemical term
stoichiometric is used to describe the best AFR, which is 14.7:1. This number
describes the proportions of air at 14.7 parts to 1 part of fuel in a combustion
reaction, required completing the consumption of all of the fuel. It is normally
expressed by mass or weight.
TECH TIP: Calorific value: The Calorific value of a fuel is the fuel heat energy
potential measured in BTUs (British thermal units), joules or calories.
VEHICLE PROTECTION ISSUE: It is important to be aware of fuel system
changes, in the event that any fuel system components require replacement during
vehicle service.
ENVIRONMENTAL ISSUE: Biodiesel is a domestically produced, renewable
fuel that can be manufactured from vegetable oils, animal fats, or recycled
restaurant greases. Biodiesel is safe, biodegradable, and reduces serious air
pollutants such as particulates, carbon monoxide, hydrocarbons, and air toxins.
Biodiesel is defined as mono-alkyl esters of long-chain fatty acids derived from
vegetable oils or animal fats which conform to ASTM D6751 specifications for
use in diesel engines. Biodiesel refers to the pure fuel before blending with diesel
fuel.
Biodiesel blends are denoted as, "BXX" with "XX" representing the percentage of
biodiesel contained in the blend (i.e; B20 is 20% biodiesel, 80% petroleum diesel).
Blends of 20% biodiesel with 80% petroleum diesel (B20) can generally be used
in unmodified diesel engines; however, users should consult their OEM and engine
warranty statement. Biodiesel can also be used in its pure form (B100), but it may
require certain engine modifications to avoid maintenance and performance
problems and may not be suitable for wintertime use. Users should consult their
engine warranty statement for more information on fuel blends of less than 20%
biodiesel.

2. FUEL & AIR SYSTEMS
Diesel Fuel
TECH TIP: Cetane Improver: Cetane improvers are fuel additives that will
increase the cetane number (CN) value of a fuel. You should only use these
chemicals if the OEM (original equipment manufacturer) recommends their use.
SAFETY ISSUE: NEVER mix diesel fuel and gasoline when refueling tanks in
the same fuel tank the combination of their different vapor pressures of gasoline
and diesel fuel creates a potential volatile solution that could cause an explosion.
TECH TIP: Lubricity: The oiliness of a substance is know as its lubricity. This
term is important because is measures the fuels ability to lubricate the moving
parts of very close tolerance injection pumps like the Stanadyne DS pump used on
the GM 6.5L EFI Diesel. When Sulfur was reduced or removed from diesel fuel,
concern was raised because this reduced the Nitrogen in the fuel, which is a major
contributor to a fuel’s lubricity.
SAFETY ISSUE: Diesel fuel is flammable and could be hot. To avoid personal
injury, NEVER touch the fuel coming from the fuel drain. NEVER expose fuel to
open flames or sparks. NEVER overfill a fuel container.
TECH TIP: Hydrogen Fuel = No Carbon: Most fuels contain hydrocarbons or
molecules that contain both hydrogen and carbon. During combustion, the first
element that is burned is the hydrogen. If combustion is complete, then all of the
carbon is converted to carbon dioxide gas and exits the engine in the exhaust.
However, if combustion is not complete, carbon monoxide is formed, leaving
some carbon to accumulate in the combustion chamber.
ENVIRONMENTAL ISSUE: The Sulfur content has been deemed an
environmental hazard and the Sulfur content of diesel fuel is now regulated to
lower Sulfur Dioxide emissions.
TECH TIP: Diesel Fuel Color: Over the road 2D diesel fuel should be clear in
color. Non-taxable off-road 2D diesel fuel is dyed BLUE. The purpose of the
dying the fuel is to identify the taxable fuel from the non-taxable diesel fuel, not
the Sulfur content.
TECH TIP: Diesel Fuel Specific Gravity is an indicator of the fuel’s cetane
number and thus the fuel quality. A poor quality diesel fuel can affect engine
performance by retarding timing.

3. FUEL & AIR SYSTEMS
Diesel Fuel
SAFETY ISSUE: Diesel Fuel Hydrometer: The glass hydrometer J-34352
including the float portion is very delicate, so extreme care must be utilized when
using this tool.
SAFETY ISSUE: It is essential to recognize the explosion hazard represented by
diesel fuel vapors. Never drain or store diesel fuel in an open container due to the
possibility of fire or explosion.
SAFETY ISSUE: During the refueling process, one may overlook the fact that
diesel fuel vaporizes and combines with air to form combustible mixtures that only
require an ignition source to cause an explosion. Diesel fuel is less volatile than
gasoline but it should always be handled with care, especially in the heat of
summer.`