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Special Instruction
SPN 3055 FMI 1 No Start Due to Low Rail Fuel Pressure Troubleshooting for Certain
CT660 On Highway Trucks{7000}
Media Number -REHS9166-00

Publication Date -2014/05/02

Date Updated -2014/05/05

i05776971

SPN 3055 FMI 1 No Start Due to Low Rail Fuel Pressure
Troubleshooting for Certain CT660 On Highway Trucks{7000}
SMCS - 7000

On Highway Truck:
CT660 (S/N: TGA1-UP; TGD1-UP; TJD1-UP; TEJ1-UP; TRK1-UP; TKL1-UP; TEM1UP; TEP1-UP; TGR1-UP; TGS1-UP; TJS1-UP; TGT1-UP; TGW1-UP; TSW1-UP; TEY1
-UP; TSY1-UP; TEZ1-UP; TGZ1-UP)

Introduction
This Special Instruction provides the information to diagnose and troubleshoot low rail fuel pressure
on the machines listed above.

Important Safety Information

Accidental engine starting can cause injury or death to personnel
working on the equipment.
To avoid accidental engine starting, disconnect the battery cable from
the negative (−) battery terminal. Completely tape all metal surfaces of
the disconnected battery cable end in order to prevent contact with
other metal surfaces which could activate the engine electrical system.

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Place a Do Not Operate tag at the Start/Stop switch location to inform
personnel that the equipment is being worked on.

Personal injury or death can result from sudden machine movement.
Sudden movement of the machine can cause injury to persons on or
near the machine.
To prevent injury or death, make sure that the area around the
machine is clear of personnel and obstructions before operating the
machine.

Do not attempt to assemble this machine until you read and you
understand the assembly instructions.
Improper assembly procedures could result in injury or death.

Personal injury can result from hydraulic oil pressure and hot oil.
Hydraulic oil pressure can remain in the hydraulic system after the
engine has been stopped. Serious injury can be caused if this pressure is
not released before any service is done on the hydraulic system.
Make sure all of the work tools have been lowered to the ground, and
the oil is cool before removing any components or lines. Remove the oil
filler cap only when the engine is stopped, and the filler cap is cool
enough to touch with your bare hand.

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NOTICE
Care must be taken to ensure that fluids are contained during
performance of inspection, maintenance, testing, adjusting, and repair
of the product. Be prepared to collect the fluid with suitable containers
before opening any compartment or disassembling any component
containing fluids.
Refer to Special Publication, NENG2500, "Dealer Service Tool
Catalog" for tools and supplies suitable to collect and contain fluids on
Cat products.
Dispose of all fluids according to local regulations and mandates.

NOTICE
Keep all parts clean from contaminants.
Contaminants may cause rapid wear and shortened component life.

NOTICE
Contact with high pressure fuel may cause personal injury or death.
Wait 60 seconds after the engine has stopped to allow fuel pressure to
purge before any service or repair is performed on the engine fuel
lines.

Note: Cleanliness is an important factor. Before beginning the removal procedure, clean the exterior
of the components thoroughly. Cleaning the components will help to prevent dirt from entering the
internal mechanism.
Note: Put identification marks on all hoses, on all hose assemblies, on all harness assemblies, and on
all tube assemblies for installation purposes. Plug all hose assemblies and all tube assemblies in order
to prevent fluid loss, and contaminants from entering the system.

SPN 3055 FMI 1 - Low Fuel Pressure at Start
Table 1

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Condition / Description

Setting Criteria

Enable Conditions /
Values

Time
Required

Engine Speed > 70 rpm

Fuel Rail Pressure (FRP)
below minimum pressure.

Fuel Rail Pressure (FRP)
less than 10000 kPa (1450
psi)

Ambient Pressure >
83 kPa (12 psi)

0.5 seconds

Ambient Temp >
−7.04 °C (19.34 °F)
Battery Voltage (before
crank) > 11 Volts

Fault Overview
Fault code sets when the Engine Control Module (ECM) detects FRP does not build within a
predetermined time while the engine is cranking.

Malfunction Indicator Lamp (MIL) Reaction
MIL will illuminate when this fault is detected during two consecutive drive cycles.

Associated Faults
SPN 94 FMI 0 (FDP), SPN 157 FMI 3, SPN 157 FMI 4, SPN 157 FMI 20, and SPN 157 FMI 21
(FRP), and SPN 633 FMI 3, SPN 633 FMI 4, and SPN 633 FMI 5 (FPCV).

Drive Cycle to Determine Fault Status
Drive Cycle 2 in Troubleshooting, UENR5715, "2013 HD-OBD Diagnostic Reference Manual".

Possible Causes
• Fuel Rail Pressure FRP sensor or circuit fault.
• Low fuel level
• Fuel leaks
• Restricted engine mounted secondary fuel filter
• Aerated fuel delivery
• Restricted fuel supply
• Internal leak in high-pressure fuel system
• Leaking FRP relief valve

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• Leaking KUEV valve
• Failed High-pressure fuel pump
Table 2
Low Pressure Fuel System Testing
Step

1

Action
Check fuel level. Read fuel level using the
vehicle instrument panel gauge and perform a
visual inspection of fluid level in the fuel tank.

2

Using Personal Computer (PC) with engine
diagnostic software, check Diagnostic Trouble
Code (DTC) list for SPN 94 FMI 0 (FDP), SPN
157 FMI 3, SPN 157 FMI 4, SPN 157 FMI 20,
and SPN 157 FMI 21 (FRP), and SPN 633 FMI
3, SPN 633 FMI 4, and SPN 633 FMI 5
(FPCV).
Is PC DTC list free of SPN 94 FMI 0 (FDP),
SPN 157 FMI 3, SPN 157 FMI 4, SPN 157 FMI
20, and SPN 157 FMI 21 (FRP), and SPN 633
FMI 3, SPN 633 FMI 4, and SPN 633 FMI 5
(FPCV)?

3

Check that the engine cranks at a minimum of
130 rpm.

4

5

6

Verify the engine starts. Crank engine for
maximum of 20 seconds. If engine does not
start, wait 2 minutes and try again.
Does engine start and maintain idle?
Check for low Fuel Delivery Pressure (FDP).
With Fuel Pressure Gauge 372-5239 connected
at inlet to secondary fuel filter, monitor FDP
while cranking.
Does FDP measure >
207 kPa (30 psi).
Check for low FDP. Perform Fuel Delivery
Pressure (FDP) Test. Refer to Level ""Fuel
Delivery Pressure (FDP) Test" ".
Is FDP >
207 kPa (30 psi) gauge or
138 kPa (20 psi) in engine diagnostic software.

Decision
Yes: Go to Step 2.
No: Add fuel or repair leaks, and prime
engine.
Yes: Go to Step 3.

No: Repair SPN 94 FMI 0 (FDP), SPN
157 FMI 3, SPN 157 FMI 4, SPN 157
FMI 20, and SPN 157 FMI 21 (FRP),
and SPN 633 FMI 3, SPN 633 FMI 4,
and SPN 633 FMI 5 (FPCV). See health
report for link to diagnostics.

Yes: Go to Step 4.
No: Repair low cranking speed.
Yes: Go to SPN 3055 FMI 15.
No: Go to Step 5.
Yes: Go to Step 9.

No: Got to Step 6.

Yes: Repair restriction in fuel supply to
Low- Pressure Fuel Pump.

No: Go to Step 7

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7

Check for failed low-pressure fuel pump.
Perform Fuel Dead Head Test. Refer to Level
""Fuel Dead Head Test" ".
Is pressure
448 kPa (65 psi)?

8

Check for a restricted engine fuel filter. Perform
High -pressure Pump Inlet Pressure Test. Refer
to Level ""High -pressure Pump Inlet Pressure
Test" ".
Does the fuel pressure gauge read
207 kPa (30 psi)?

9

Check for aeration in low-pressure fuel system.
Perform Fuel Aeration Test. Refer to Level
""Fuel Aeration Test" ".
Is fuel system free from aeration?

10

Check for restriction in low-pressure fuel
system. Perform Fuel Restriction Test. Refer to
Level ""Fuel Restriction Test" ".
Is fuel system free of restriction?

Yes: Go to Step 8.
No: Replace High Pressure (HP) fuel
pump.
Yes: Go to Step 9.

No: Replace Engine Fuel Filter.
Yes: Go to Step 10.
No: Repair aeration in low-pressure fuel
system (according to Fuel Aeration
Test).
Yes: Go to Step 11.
No: Repair restriction in low-pressure
fuel system (according to Fuel
Restriction Test).

Table 3
High Pressure Fuel System Testing
Step

11

12

13

Action
Check for fuel return. Perform Fuel Rail Pressure (FRP) Return
Flow Test part 1. Disconnect fuel drain tube assembly at rear of
cylinder head. Connect High Pressure Return Line Tester 373-4728
-1 to cylinder head and route other end to diesel fuel container.
Crank engine for 20 seconds while monitoring fuel return from
High Pressure Return Line Tester 373-4728-1.
Is the line free of return fuel from cylinder head and rail?
Check for a failed fuel pressure relief valve. Perform Fuel Rail
Pressure (FRP) Return Flow Test part 2. Restore all fuel line
connections. Disconnect fuel rail return line at fuel rail. Connect
High Pressure Return Line Tester 373-4728-1 to fuel rail return
port and route other end to diesel fuel container. Crank engine and
monitor fuel return from High Pressure Return Line Tester 3734728-1.
Is the line free of return fuel from fuel rail?

Decision

Yes: Go to Step 12.

No: Go to Step 14.

Yes: Go to Step 13.

No: Replace fuel rail.
Yes: Replace High
Pressure (HP) fuel

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Check for a failed KUEV Valve. Complete the HP Pump Return
Flow Test. Refer to Level ""HP Pump Return Flow Test" ".
Is fuel line free of fuel from the high-pressure pump return port?

14

Check for an internal leak in the high-pressure fuel system.
Perform Fuel Rail Pressure (FRP) Leak Isolation Test. Refer to
Level ""Fuel Rail Pressure (FRP) Leak Isolation Test" ".
Is engine free of leaking injector?

pump then go to step
15.
No: Replace KUEV
valve.
Yes: Retest for SPN
3055 FMI 1 and if it
remains notify
supervisor.
No: Replace the last
capped injector and
all HP lines removed
during this test.
Yes: Retest for SPN
3055 FMI 1.

15

Run HP Pump Fuel Return Pressure Test. Refer to ""HP Pump Fuel
No: Repair restriction
Return Pressure Test" ".
in fuel return line
Is Pressure
between high 90 kPa (13 psi)?
pressure fuel pump
and fuel tank.

Note: After performing all diagnostic steps, if SPN 3055 FMI 1 remains, verify that each step was
completed correctly and the proper decision was made. Notify supervisor for further action.
Table 4
Quantity

1