Electrical Origin Of "fat Blue Spark" Referenced In Cranks Okay/no Start Checklist

DuderMcMerican

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Mar 7, 2016
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Woodbridge, VA
Probably a cherry newb question, but when jrichker's diagnosis checklist says "Jumper the screw to the big bolt on the starter solenoid that has the battery wire connected to it. You should get a nice fat blue spark," where should the blue spark be coming from? I get a smallish blueish/orangey spark at the big bolt on the starter solenoid and sometimes a bigger blue spark jumping off the coil post. I thought the spark should jump between the coil wire and engine block, no?

There also a loudish click, and it seems like the engine tries to turnover about half a crank. Normal?
 
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jrichker

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"Jumper the screw to the big bolt on the starter solenoid that has the battery wire connected to it." That causes the engine to crank. With the ignition switch in the Run position the ignition coil will generally create enough voltage to make a spark.

Disregard any small sparks at the starter solenoid when you jumper the screw to the big bolt on the starter solenoid, they are not important at this time.

The observation should be that a fat blue spark jumps from the coil wire to ground. The engine should continue to crank as long as you continue to jumper the screw to the big bolt on the starter solenoid. As the engine cranks, the spark from the coil wire should continue to jump to ground.

If you have spark jumping places other that the coil wire to ground as the engine cranks over, you have some insulation problems or a bad high voltage coil wire.
 

DuderMcMerican

Active Member
Mar 7, 2016
148
9
28
Woodbridge, VA
The observation should be that a fat blue spark jumps from the coil wire to ground. The engine should continue to crank as long as you continue to jumper the screw to the big bolt on the starter solenoid. As the engine cranks, the spark from the coil wire should continue to jump to ground.

If you have spark jumping places other that the coil wire to ground as the engine cranks over, you have some insulation problems or a bad high voltage coil wire.
Okay, thanks for clarifying. Looks like I'm in the "no spark" club then. I already plugged a noid light into injector 5, and it blinked steadily with engine running. I'll move on to checking the TFI module.
 
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