Cub Cadet Challenger 550, Service Manual

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Troubleshooting
8‐2
5. Turn the engine over using the Key switch. A fat blue spark must be evident between
the spark tester or spark plug terminals.
6. If there is a strong, blue spark, the ignition system is functioning properly, Check for
one or more of the following possible malfunctions:
• Faulty fuel system component.
• Flooded engine.
• Engine damage (low compression).
7. If the spark was weak (white or yellow) or if there was no spark, perform the peak
voltage checks described under Ignition System Testing.
Fuel System
The following section isolates common fuel system problems. If there is a good spark,
poor fuel flow may be preventing the correct amount of fuel from being supplied to the
cylinder. Troubleshoot the fuel system as follows
:
1. Check that there is a sufficient amount of fuel in the tank.
2. Turn the ignition Key to the run position and listen for the fuel pump motor to
come on.
3. If nothing is heard check all wire connections going to the fuel tank. 2 wires go
to the back of the unit and 2 wires go to the front of the unit. Find the white 2
pin connector that goes toward the throttle body and connect 12v. Do you hear
the pump motor come on? If yes, then the pump motor is good. If no, we are
not getting the voltage from the centralized relay box.
4. Remove the spark plug and inspect for excessive fuel. If there is fuel present on
the plug tip. And the engine has spark. Check for an excessive intake air leak
or the possibility of contaminated or stale fuel.
Note:
If the UV was not used for some time, and was not properly stored, the fuel may
have gone stale. Depending on the condition of the fuel, a no-start condition can
result.
Compression test
Problems with the engine top end will affect engine performance. When the engine is
suspect, perform the leak down and a compression test. Interpret the results as
described in each procedure to troubleshoot the suspect area. An engine can lose
compression through the following areas:
1. Valves:
•
Incorrect valve adjustment.
• Incorrect valve timing.
• Worn or damaged valve seat surfaces.
• Bent valves.
• Weak or broken valve springs.