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3. TESTING PROCEDURE
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WARNING! Before using equipment ensure you have read, understood and apply Section 1 safety instructions.
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3.1. Pre-Test checks
1.
Do a thorough visual and "hands-on" inspection of the engine and fuel system. Look for loose or cracked electrical wiring, battery
cables, ignition wires, and fuel or vacuum lines.
2.
Verify that the battery is fully charged and fuel tank has adequate fuel.
3.
Verify that the inertia fuel cut-off switch (if fitted) has not been actuated - see vehicle manual.
4.
Verify that all fuel system fuses are good.
5.
Verify that the fuel vapour recovery system and filler cap are in good condition.
6.
Verify that manifold vacuum is within manufacturer’s specification (typically 18-20 in.Hg at idle).
7.
Look for fuel leaks and wipe up any spilled fuel immediately.
8.
Has the vehicle been serviced recently? Sometimes things get reconnected incorrectly, or not at all.
9.
Do not take shortcuts. Inspect wiring which may be difficult to see because of location beneath air cleaner housings, alternators, etc.
10. Inspect wiring harnesses for:
Contact with sharp edges (this happens often).
Contact with hot surfaces, such as exhaust manifolds.
11. Check electrical connectors for:
Corrosion on pins.
Contacts not properly seated in housing.
Note: Problems with connectors are common in the engine control system - inspect carefully. Note that some connectors use a special grease on
the contacts to prevent corrosion. Do not wipe off! Obtain extra grease, if needed, from your vehicle dealer. It is a special type for this purpose.
12. Check other vehicle systems:
Ignition - For safety reasons, many engine management systems will not deliver fuel without an ignition spark.
13. Electronic Control Unit (ECU) - The engine management system ECU has special drivers which energize the fuel injectors. These drivers
are fragile and can easily fail. If you suspect an ECU driver problem, check by replacing the ECU with a known good one and retest.
14. Perform diagnostic procedures as described in vehicle service manual to eliminate other possible causes of driveability problems.
Compression and ignition problems may imitate fuel injection system problems.
3.2. Testing
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WARNING! Before proceeding with fuel injector and harness testing, read and understand all safety guidelines and perform all pre-test checks.
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3.2.1.
Fuel Injector test
1.
Connect Tester to vehicle battery. RED clip to the positive (+) terminal and BLACK clip to the negative
(-) terminal.
Ensure that Power LED is lit before continuing.
2.
Connect a Fuel Pressure Gauge (VS210, not included) to fuel line. Some vehicles have a schrader
valve located on the fuel rail for this purpose.
On vehicles without schrader valves, you must open the fuel line at the appropriate point to insert
a fuel pressure gauge adaptor.
IMPORTANT: Always follow fuel pressure gauge and vehicle service manual instructions and
safety precautions when opening fuel lines.
The information in this manual is not a substitute for the procedures outlined in the vehicle service manual.
ALWAYS follow manufacturer's instructions and safety precautions when working on fuel systems.
3.
Depressurize fuel system by following procedure outlined in vehicle service manual. On most
vehicles, this involves disconnecting or deactivating the electric fuel pump(s) and operating the
engine until it stalls. Note: Some vehicles may have more than one fuel pump - deactivate all pumps!
Failure to do so can result in personal injury, vehicle damage, spilled fuel, fire or other hazardous conditions.
4.
Using proper fuel pressure gauge adaptor, open fuel line at point specified in vehicle service manual and connect adaptor to fuel line.
5.
Attach fuel pressure gauge to adaptor and tighten fitting until finger tight.
IMPORTANT: Read and follow all pre-test checks, safety instructions, and fuel pressure testing procedures contained in this document and in
vehicle service manual.
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WARNING! Always use caution when working around fuel systems. The fuel in the fuel rail may be pressurized even if the
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engine is not running. Use a rag to cover the schrader valve or fitting whenever opening the fuel system to attach gauge. Clean all fuel spills
immediately.
3.2.2.
Test for fuel system leaks
1.
Pressurize fuel system by cycling ignition ‘ON’ and ‘OFF’ every ten seconds until fuel pressure is to manufacturer's specification (check
vehicle service manual).
Note: Check fuel pressure gauge connection points for leaks. If leak occurs, clean all fuel spills immediately and check all fittings for tightness.
2.
Observe pressure gauge for 10 -15 seconds, looking for pressure drop.
3.
If the pressure does not drop, continue with fuel injector testing. If fuel pressure does drop, continue looking for leaks by blocking off the
return line between the fuel pressure regulator and the fuel tank. Re-test as described above.
4.
If the pressure drops again, there may be one or more leaky injectors. Later tests will identify malfunctioning injectors.
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Pinched, burned of chafed insulation.
Proper routing and connections.
Bent or damaged pins.
VS211-0527-(1)-240599
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