DDFP SERIES ENGINES FOR FIRE PUMP APPLICATIONS MP-4. Manual - part 5

DDFP

SECTION 3

Page 12

ENGINE SYSTEMS

OPERATION

Fuel is drawn from the supply tank through the fuel strainer

and enters the fuel pump at the inlet side. Upon lea ving the

fuel pump under pressure, the fuel is forced through the fuel

filter and into the fuel inlet manifold where it passes through

fuel pipes into the inlet side of each fuel injector. The fuel is

atomized through small injector spray tip orif ices into the

combustion chamber. Surplus fuel, returning from the injec-

tors, passes through the fuel return manifold and connecting

fuel lines back to the fuel tank.  The continuous flow of fuel

through the injectors helps to cool the injectors and to

remove air from the fuel system.

CHECK VALVE

A check valve is installed between the fuel filter and the fuel

inlet manifold. The check valve is rated to open at approxi-

mately 2 psi (13.7 KP A).  The fuel tank and supply lines

should be arranged to limit static pressure so that the v alve

remains closed when unit is not running.  This valve opens

automatically from fuel pump pressure when the unit starts.

Refer to Figure 1, Page 14, for fuel system components.

FUEL INJECTOR

The fuel injector combines in a single unit all of the parts

necessary to pro vide complete and independent fuel injec-

tion at each c ylinder. The injector creates the high pressure

necessary for fuel injection, meters the proper amount of

fuel, atomizes the fuel, and times the injection into the com-

bustion chamber.

FUEL SYSTEM

In this 

Engine Systems

section that follows, data is pre-

sented in a generalized way for a description of system oper-

ation. For specific operational data and system limits, refer

to Section 5. In addition to kno wing the specif ic DDFP

model being operated, make special note of the certif ied

engine operating speed (RPM). Much of the data v aries by

operating RPM - check the FM/UL/ULC certification tag on

the engine flywheel housing for this speed.

Section 3.1

Fuel System

Section 3.2

Air Intake & Exhaust System

Section 3.3

Lubrication System

Section 3.4

Cooling System

Section 3.5

Electrical System

Section 3.6

Falk Drive Coupling

Since the injector is one of the most important and careful-

ly constructed parts of the engine, it is recommended that

the injector be replaced as an assembly if it is not operating

properly. An authorized DDC Distributor/Dealer is equipped

to pro vide ne w and reconditioned replacement injectors.

Under no circumstance should an attempt be made to repair

these injectors. Genuine f actory new or "reliabilt" injectors

should be used for repairs.

FUEL PUMP

DDFP Engines are equipped with a positi ve displacement

gear type fuel transfer pump. Fuel pumps are furnished in

either left or right hand rotation according to the engine

model, and are stamped  RH or LH. These pumps are not

interchangeable and cannot be rebuilt to operate in an oppo-

site rotation. The fuel pump used on the 53 series engine is

driven by the governor assembly on the left rear . On I-71 it

is attached and driven off the rear of the lower engine blow-

er rotor. On VEE engines, the pump is attached and dri ven

off the right front blo wer rotor located on the v ee of the

block.

A spring-loaded relief valve, incorporated in the pump body,

normally remains in the closed position,

operating only

when the pressure on the outlet side (to the fuel f

ilter)

becomes excessive due to a plugged filter or fuel line.

The fuel pump incorporates two oil seals. Two tapped holes

are provided in the underside of the pump body, between the

oil seals, to permit a drain tube to be attached. If fuel leak-

age exceeds one drop per minute,the seals must be replaced.

An authorized DDC Distributor/Dealer is properly equipped

to replace the seals or to pro vide reconditioned parts.

SECTION 3.1

DDFP

Page 13

SPIN-ON TYPE FUEL FILTER

A spin-on type fuel strainer and fuel filter (Fig. 2) is used on

Clarke DDFP engines.  The spin-on f ilter cartridge consists

of a shell, element and gasket combined into a unitized re-

placement assembly. No separate springs or seats are re-

quired to support the filters.

The filter base incorporates a threaded slee ve to accept the

spin-on f ilter cartridges. 

The w ord "Primary" or

"Secondary" is cast on the fuel strainer base for identif ica-

tion.

No drain cocks are pro vided on the spin-on f ilters. Where

water is a problem, residue may be drained by removing and

inverting the filter. Refill the filter with clean fuel oil before

reinstalling it. Should water be found, locate the source and

correct by draining or cleaning as required.

Replace the Filter as Follows:

1. Unscrew the filter (or strainer) and discard it.
2. Fill a new filter replacement cartridge full with clean fuel

oil. Coat the seal gasket lightly with clean fuel oil.

3. Install the new filter assembly and tighten it to two-thirds

of a turn beyond gasket contact.

4. Start the engine and check for leaks.

NOTE:

DDFP engines have the "Primary" filter at or below

the fuel pump. One exception to this is current pro-

duction I-53 engines. Due to f

actory designed,

formed steel fuel lines, the I-53 filters are mounted

the reverse of all others. The Primary Filter mounts

to the c ylinder head abo ve the pump. 

The

Secondary filter mounts to the coolant w ater inlet

elbow below the fuel pump. Inlet fuel check valves

are always located on the discharge side of the sec-

ondary filter.

DIESEL FUEL RECOMMENDATIONS

The quality and grade of fuel used is a very important factor

in obtaining satisf actory engine performance, long engine

life, and acceptable e xhaust emission le vels. Certif ied

engine ratings are based at standard SAE conditions using

the recommended #2-D Diesel Fuel. Refer to the Diesel Fuel

Specifications chart Fig 3 for verification of fuel properties.

For additional information on the fuel system, see technical

data Section 5, Page 43. In addition, Sulfur content of the #2

Diesel Fuel used must be limited to 0.5% mass.  The com-

Gravity, °API #

Flash Point, Min. °F (°C)

Viscosity, Kinematic

cST @ 100°F (40°C)

Sulfur Content wt%, Max.

Carbon Residue

on 10%, wt%, Max.

Accelerated Stability

Total Insolubles

mg/100 ml, Max. #

Ash, wt%, Max.

Cetane Number, Min. +

Cetane Index, Min. +

Distillation Temperature,

°F (°C)

IBP, Typical #

10% Typical #

50% Typical #

90% +

End Point #

Water & Sediment 

%, Max.

General Fuel
Classification

# Not Specified in ASTM D 975 ........................................

+ Differs from ASTM D 975

Fig. 3 - Diesel Fuel Specifications Chart

33 - 37

125 (52)

1.9 - 4.1

0.5

0.35

1.5

0.01

45

40

375 (191)

430 (221)

510 (256)

625 (329) Max.

675 (357) Max.

0.05

D 287

D 93

D 445

D 1266

D 524

D 2274

D 482

D 613

D 4737

D 86

D 1796

ASTM

Test

No. 2

ASTM 2-D

DDFP

SECTION 3.1

Page 14

FUEL SYSTEM SCHEMATICS

Fig. 1 - DDFP Fuel System

1. Fuel Strainer (Primary)

2. Fuel Transfer Pump

3. Fuel Filter (Secondary)

4. Check Valves

5. Cylinder Head with Internal Manifolds

6. Fuel Injectors

7. Fuel Pipes (Inlet and Return to Injector)

8. Restricted Fuel Fitting

9. Return to Tank

ENGINE MECHANICAL GOVERNOR

A v ariable speed mechanical go vernor pro vides speed

control of the engine.  The certified engine speed, shown on

FM/UL/ULC label, has been preset at the f actory. Minor

speed adjustments can be made in the f ield to meet specific

installation condition, generally ± 50 RPM maximum.

The go vernor is controlled by the R UN-STOP solenoid.

This solenoid is activated by a signal from the AEC. A man-

ual over-ride switch on the instrument panel, placed in the

MANUAL

position, allows manual operation should the

AEC malfunction.

Note:

Always leave the instrument panel switch in the

AUTO

position when the unit is unattended.

SECTION 3.1

DDFP

Page 15

MAINTENANCE AND SERVICE PROCEDURES

Figure 2

I-53 Fuel Filters

I-71 Fuel Filters

V-92 Fuel Filters

V-71 Fuel Filters

Weekly

1). Fuel Tank: Keep the fuel tank f illed to reduce conden-

sation to a minimum. Open drain at the bottom of the

fuel tank once a week to drain of f any possible w ater

and/or sediment. Fill tank after each test run.

NOTE:

Per NFPA 20 standards, the fuel tank level must

never be less than 50% of capacity.

2). Fuel: Use a proper grade of #2-D diesel fuel only .

6 Months

Check condition of fuel lines for fraying, leaks or poor  con-

dition. Replace as necessary.

Yearly

Change primary and secondary fuel filters. Refer to Section

6 for recommended part numbers. 

DIESEL FUEL CONTAMINATION

The most common form of diesel fuel contamination is

water. Water is harmful to the fuel system and it also pr o-

motes the growth of microbiological organisms (microbes).

These microbes clog fuel f ilters with a "slime" and restrict

fuel flow.
Water can be introduced into the fuel supply through poor

maintenance (loose or open fuel tank caps), contaminated

fuel supply or condensation.
Condensation is particularly prevalent on units which stand

idle for e xtended periods of time, such as f ire pump units.

Ambient temperature changes cause condensation in partial-

ly filled fuel tanks.
Water accumulation can be controlled by mixing isoprop yl

alcohol (dry gas) into the fuel oil at a ratio of one pint per

125 gallons fuel (or 0.10% by v olume).
Microbe growth can be eliminated through the use of com-

mercially available biocides.  There are tw o basic types on

the mark et.  The w ater soluble type treats only the tank

where it is introduced. Microbe growth can start again if fuel

is transferred from a treated to an untreated tank. Diesel fuel

soluble type, such as "Biobor" manufactured by U.S. Borax

or equivalent, treats the fuel itself and therefore the entire

fuel system. Please follow manufacturer's recommendations

on useage of these materials.

Engine Out of Fuel

The problems of restarting an engine that has run out of fuel

involves the entire fuel system.  After the fuel is e xhausted

from the fuel tank, fuel is then pumped from the primary

fuel strainer and sometimes partially removed from the sec-

ondary fuel filter before the fuel supply becomes insufficient

to sustain engine firing.
To ensure prompt starting and smooth running, the fuel sys-

tem must be pur ged of air and full of fuel from the supply

tank to the restricted fitting at the fuel return line. To accom-

plish this, a manual priming pump, such as tool P/N J5956

or an electrical type priming pump can be adapted easily to

the fittings provided on the secondary f ilter. To be sure the

injectors are lubricated, priming through the secondary filter

is preferred. The system should be primed until no air is pre-

sent in the fuel flow from the return line. Pressure should not

exceed 15 psi (103kPa) for ease of handling and safety rea-

sons.
Priming is not al ways necessary if the f ilter elements are

filled with fuel when installed and the fuel manifolds in the

head are not drained of fuel. Prolonged use of the starter

motor and engine fuel pump to prime the system can result

in damage to the starter, fuel pump, injectors and erratic run-

ning of the engine, due to the amount of air in the lines and

filters from the supply tank to the c ylinder head.

NOTE:

Under no circumstances should a starting aid

such as ether be used to run the engine until the

fuel system is primed. Injector damage will

occur if this method is used. The heat generated

by the external fuel source will cause the tips to

be damaged when the fuel cools them. 

The