Vanguard BIG BLOCK M540000, Repair Manual, Page: 26 / 168

11. See Figure 24. Install free end of spark plug wire onto
inline tester prong. Install tester alligator clip onto spark
plug terminal.
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12. If equipped, move throttle control lever to FAST.
13. Activate the starter motor allowing the engine to crank.
Observe the spark tester window. If spark jumps the
tester gap, install a new spark plug. If a spark is
observed jumping the tester gap, install a new spark
plug.
14. If spark is not present, move to step 15.
15. If spark is not present, look for:
• Improperly operating low oil sensor system, if
equipped
• Shorted equipment or engine stop switch wire
• Incorrect armature air gap
• Armature failure
• Ignition coil failure
• Incorrect crank position senor air gap
Check Fuel System - Carbureted Engine
1. Verify that fuel tank has an ample supply of fresh, clean
gasoline.
2. Test fuel for alcohol content using an alcohol tester. See
SECTION 1 - SAFETY AND GENERAL INFORMATION -
Fuel Recommendations for approved fuel alcohol content.
3. Verify that the fuel shutoff valve is open, if equipped, and
that fuel flows freely through the fuel line. If fuel flow is
slow or fails to flow, check for plugged fuel cap vent, fuel
line restriction, or plugged fuel filter.
4. Verify that throttle and choke controls are properly
adjusted.
5. If engine cranks, but will not start, remove and inspect
the spark plug.
6. A wet spark plug may indicate:
• Over choking
• Excessively rich fuel mixture
• Water in fuel
• Carburetor float needle valve stuck open
• Plugged air cleaner
• Fouled air cleaner
7. A dry spark plug may indicate:
• Leaking carburetor or intake manifold gaskets
• Gummy or dirty carburetor, fuel filter, fuel lines, or
fuel tank
• Carburetor float needle valve stuck closed
• Inoperative fuel pump (if equipped)
• Inoperative fuel shut-off solenoid (if equipped)
NOTE: To determine if the fuel is getting to the combustion
chamber through the carburetor, remove the spark plug and
pour a small quantity of gasoline through the spark plug hole.
Install the spark plug and crank the engine. If the engine fires
a few times and then stops, look for the same conditions as
for a dry spark plug.
Check Fuel System - Fuel-Injected Engine (EFI)
For troubleshooting steps and checks related to EFI systems,
consult the applicable EFI Diagnostics and Repair Manual for
your engine.
The start of any troubleshooting process must always contain
a visual inspection of the system and its components. This
check must always include the following:
• Verify that ECM grounds and sensor connections are
clean, tight and in their proper location.
• Thoroughly check for any type of vacuum leak or
restriction.
• Look for air leaks at the throttle body mounting and
intake manifold sealing surfaces.
• Inspect ignition wires for cracks, hardness, improper
routing and carbon tracking.
• Inspect wires for kinks, cuts, burns, abraded insulation,
and other damage.
• Look for moisture in primary or secondary ignition circuit
connections.
• Look for salt corrosion on electrical connections and
exposed throttle body linkages.
Check electrical connectors for the following:
• Poor mating of connector halves, or a terminal not fully
seated in the connector body (backed out or loose).
• Improperly formed or damaged terminals and/or
connectors.
• Improper contact tension of connector pin and socket
terminals in the problem circuit.
• Poor terminal to wire connection (both core and
insulation crimps).
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