Fuel System; Electrical System - NEO TOOLS 11-264 Mode D'emploi

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7. BASIC DIAGNOSTIC CHECKS
Before testing the fuel injection system it is recommended to carry out the following basic checks:
7.1

FUEL SYSTEM

7.1.1. Ensure that there is sufficient fuel in the fuel tank. Do not rely on the vehicle's fuel gauge, make a physical check.
7.1.2. Check for damaged, broken or loose metal and flexible fuel lines. Look for evidence of fuel leaks.
7.1.3. Ensure that there is no water or any other contaminants in the fuel.
7.1.4. Check the fuel tank venting system and the condition of the fuel filler cap.
7.1.5. Check any fuel system related electrical fuses.
7.2

Electrical system

7.2.1. Look for any disconnected electrical components.
7.2.2. Check the vehicle ignition system and ensure that the spark plugs are functioning correctly.
7.2.3. Observe for any fault lamps illuminated on the vehicle dashboard. If necessary use an eobd code reader (available from your sealey
dealer) to retrieve any fault codes from the vehicle.
7.2.4. Check the condition of the battery as the electrical components on the fuel injection system will rely on the battery to function.
7.3 Vacuum system
7.3.1. Check the vacuum system for any loose or disconnected pipes.
7.3.2. With the engine running, listen for any air leaks or unusual noises.
7.3.3. Look for any oil leaks in or around the vacuum system.
7.3.4. Check the inlet manifold for cracks or leaking gaskets.
8. BASIC FUEL INJECTION PRESSURE TESTING.
Fuel injected engines require precise fuel pressure as well as adequate volume. Without the correct pressure and volume, performance and fuel economy
can suffer. Always consult the correct workshop manual or vehicle manufacturer for accurate specifications and testing procedures.
When running tests, it may help to picture the fuel system as a circle. Fuel is pumped from the tank to the fuel regulator and injectors, and the unused fuel
is then returned to the tank. The fuel regulator serves as a divider between the supply side and the return side.
The adaptors supplied with this kit are suitable for use on most fuel injection systems fitted to american, european and asian vehicles. There are three ways
to check fuel pressure. First, many vehicles with pfi are equipped with a special test port. Simply connect the proper adaptor to the gauge assembly, thread
the adaptor to the test port, and run the test. Second is an end of hose connection. Some older pfi systems have a flexible hose connection at the cold start
injector. Connect the single barb fitting with a hose clamp to run the test. Also, some systems have fuel bolts or banjo type fittings as an access point. Third
is in-line connecting. This means installing the proper adaptor(s) in series with the fuel line.
Unless a schrader-type test port is available, most manufacturers require that you relieve the fuel pressure before entering or leaving the system. To relieve
the pressure, it may be necessary to remove the fuel pump connector, relay, or fuse. Some models may have two fuel pumps - make sure both are disabled.
After the pump(s) is/are disabled, run the engine until it stalls, then try to restart it for five to ten seconds. The system is now ready for testing.
8.1 BASIC TESTING PROCEDURE
Note: the following is intended as a guide only, always refer to the vehicle manufacturer or a workshop manual for specific fuel injection system pressure testing.
Caution: high fuel pressure may be present in fuel lines and component parts. Relieve pressure before attempting to open system for testing or component
replacement. Do not allow fuel to run onto engine or electrical parts while testing fuel system components.
8.1.1. Ensure that the ignition and engine is switched off before the test.
8.1.2. Connect the gauge assembly to the high pressure side of fuel injection system by one of the methods as described above using the
correct adaptor. Where necessary, ensure that the pressure has been relieved from the fuel system.
8.1.3. Carry out the test procedures as stated by the manufacturer or workshop manual. Note: any testing that requires the engine to be
running should only be done at tickover.
8.1.4. Observe reading on gauge assembly and compare to vehicle manufacturer's specifications.
A higher than normal pressure usually indicates a problem on the return side of the circle and a lower than recommended pressure usually indicates a
problem on the supply side of the circle.
8.2 Possible causes of higher than recommended fuel pressure.
8.2.1. Defective fuel pressure regulator.
8.2.2. Restriction in fuel return line.
8.2.3. Defective safety valve or fuel pump at tank.
8.2.4. Excessive tank pressure caused by improper venting.
8.3 Possible causes of lower than recommended fuel pressure.
8.3.1. Blocked fuel filter.
8.3.2. Restriction in fuel supply line.
8.3.3. Defective fuel pump
8.3.4. Defective pressure regulator
8.3.5. Blocked pump inlet filter
8.3.6. Vacuum in tank caused by improper venting.
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