Pressure Diagnosis
HP 2.9
Common Rail
Troubleshooting
Pressure Diagnosis
This means that a pressure fault may come from the Producer,
The Regulator or the Consumers. Simply studying the physical
perametres of the rail Pressure does not allow the
disassosiation of producer and consumer.
2. Symptoms
The engine will not or is difficult to start.
The engine stalls while running.
Lack of power and check lamp is on: the recovery mode may
lead to engine stop.
Hydraulic System Status Analysis.
In order to fully understand the fault codes linked to pressure
control, it is necassary to analyse the hydraulic system status
Troubleshooting
Pressure Diagnosis
3. Hydraulic system status analysis
Hydraulic flow balance is established as follows:
Injected flow + Back leak flow (Flow consumed) =
Capacity of the HP pump to supply the flow Requested for a given Diesel
fuel temperature and pump inlet depression
Consumption
Pressure potential
Pressure reserve necessary for
Correct function of the system
Backleak flow
Injector flow
Pressure
demand
Capacity of the pump to supply a f
low at a given pressure
Troubleshooting
Pressure Diagnosis
The hydraulic flow balance is upset if:
-The injector backleak increases sharply, exceeding the pump
capacity. This can happen when particles disturb the injector in
ternal sealing, increasing the backleak flow from one or more
injectors
Examples:
Heavy contamination of the fuel
Wear and tear on the pump leads to the
production of metallic particles that will
seriously disturb injector function
Mechanical wear in the injector.
Increased back flow
Pressure deficit
100
100
Backleak flow
Pump capacity
Injector flow
0
Consumption
0
Production
Troubleshooting
Pressure Diagnosis
The capacity of the pump to supply the required pressure is
reduced due to internal pump wear or a fuel feed problem
Example.
Presence of air in the low pressure circuit
Excessive negative pressure at the
pump inlet (<-300mBar)
Mechanical wear in the pump
Excessive pump inlet
temperature (>65°C)
Reduction in HP capacity
100
100
Pressure deficit
Backleak flow
Pump capacity
Injected flow
0
Consumption
0
Production
Troubleshooting
Pressure Diagnosis
4. Diagnosis
The following diagnosis flow chart summarises the variuos
successive injection system checks for the isolation of faulty Components
Logical order for diagnostic operations
Troubleshooting
Pressure Diagnosis
4. Tools
The listed tools are required to carry out the
following test procedures.
HP pump return line
blocking hose
- Addittional battery power
- Hi-Scan
- Vacuum gauge
- 2 meters clear plastic pipe Ø 4mm
- 4x plastic with measuring scale (injector tester)
- Delphi special tool
- Eye protection
Delphi SST
`Closed Rail´
Troubleshooting
Pressure Diagnosis
The on vehicle system hydraulic status test:
The system must be prepared for the test as follows: Disconnect the IMV elecrically by disconecting the BROWN connector on the high pressure pump, and disconnect the injector
electrical connection so that they are no longer managed by the ECU.
This will allow the maximum pressure to be reached.Turn the engine over on the starter for 5
seconds only:
The five second period is critical, nothing is gained from exceeding this time limit, and it
is dangerous to do so.
Note: The cranking speed must exceed 200 RPM.
The minmum pressure reached must be 1050 bar
If the rail pressure is below 1050 bar
Go to section 4-3 to 4-5 to isolate the faulty component/s
At this stage the system capacity can be regarded as insufficient.
If the rail pressure is above 1050 bars
The root cause of the problem lies outside the capacity of the system to produce pressure
Use the routine diagnostic documents
Troubleshooting
Pressure Diagnosis
4-3 Satic Injector Backleak Test
The backleak flow volumes must be measured, if the engine will not Start, it is only possible t
o measure the static flows (ie. Unmanaged closed injectors under high pressure).
Disconnect and remove return line from injectors and pump
Connect clear 4mm internal diameter plastic tubes to all the injector backleak ears, (the 4m
m internal diameter is critical)
Plug the pump venturi connection (to prevent airlocks in the low pressure circuit)
Disconnect the Brown IMV electrical connector and the injector electrical connectors
(An addition battery may be required)
Do not exceed the 5 sceonds.
The cranking speed should must be above 200RPM. Measure the quantity of diesel fuel
obtained in 5 seconds in cm.
Refer to the table in section 5.
Repalce any injectors whose backleak exceeds the given value in the table.
Empty the tubes, re-connect them and perform the test again with new injectors (5 Sec on the
starter) Replace any injectors that exceed the value
Troubleshooting
Pressure Diagnosis
4-3 Satic Injector Backleak Test
Plug the venturi connection
(to prevent airlocks in the
low pressure
Disconnect the Brown IMV electrical connector
Disconnect the injector
electrical connector
Troubleshooting
Pressure Diagnosis
4-3 Satic Injector Backleak Test
Measure the amount of leak fuel in (cm)
Troubleshooting
Pressure Diagnosis
4-4 Dynamic Injector Backleak Test
In cases where the engine will run, the leak detection cycle allows the dynamic backleak flow
to be checked (with engine running) from 230 to 1400 bars.
Connect the containers or tubes to the injector backleak pipes Plug the pump venturi
connection (to prevent airlocks in the low pressure system)
Connect the Hi-Scan, (erase any DTC´s present)
Run the engine at idle for two minutes and perform two consecutive leak detection cycl
es. (note: Intercooler must be in place)
Measure the volume of diesel fuel collected and refer to the table in
section 5.
Replace any injectors whose backleak volume exceeds the reference table.
Troubleshooting
Pressure Diagnosis
4-5 Pump pressure generation capability
This test is designed to check the pressure generagted by the pump
onsuming elements of the system
when isolated from the c
SST: Plugged rail tool is required.
Connect the plugged rail to the pump HP outlet and the rail pressure sensor connector to the
plugged rail sensor. Plug the engine rail inlet, to protect against dirt.
Disconnect the IMV electrical connector
Connect the Hi-Scan, (erase any DTC´s present)
Read the rail pressure while cranking the engine on the starter for five seconds only. Do
not exceed the five second limit
(An addition battery may be required)
Note: The engine speed should be grater than 200RPM during the test.
If the pressure reached during the test is less than 1050 bars, the HP pump musst be
replaced.
After test excess pressure must be released, using a 2.5 mm key
screw allowing the fuel to drain into a container.
slowly open the bleed
Troubleshooting
Pressure Diagnosis
HP pipe
Pressure
sensor
Rail discharge
Delphi SST: Plugged Rail Tool
Connected to vehicle
wiring harness
Tool in place Tool
Troubleshooting
Pressure Diagnosis
5. Values by applications for pipes and containers methods
Model
Application
Pipe method (value in cm)
Container method (value in ml)
10 cm
10 cm
10 cm
TBD
20 ml
35 ml
35 ml
35 ml
Ford Lynx
Ford Puma
21 cm
20 cm
/
/
Hyundai (J-3 2.9)
Kia
(J-3 2.9)
20 cm
20 cm
25 ml
25 ml
PSA DV4TED4
soft G6B60 only
TBD
37 ml
Renault
Renault
Renault
Renault
K9K700
K9K704
K9K702
K9K722
Troubleshooting
Compression Testing
In order to check the cylinder compressions, please adopt the
following procedures
1.
Remove injectors
2.
Remove high pressure pipe from pump to rail
3.
Install SST `Closed Rail´
In this way the fuel curcuit is closed and the pump still has lubrication
Note:
Do not perform a compression test without the closed rail tool;
risk of fuel leaking under pressure.
Do not run interupt the fuel intake to prevent engine running or
pressure production, risk of mechanical damage to the pump due to
lack of lubrication