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No Spark, Low Cranking Voltage


RTB

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I have done a Matchbox swap by the books and still no luck getting a spark. My cranking voltage is only 8.5 volts from the C point on the dizzy to ground. No idea why I am losing volts, especially since I have a brand new coil. I tried with another brand new coil and still no luck. I am out of ideas.

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EIwiringtocoil.jpg

 

That could be correct as there will be a voltage drop through the coil. The C terminal should intermittently drop to zero voltage or close while cranking as the matchbox 'turns' the ground on and off to fire the coil. The B terminal should have 12 volts with ignition ON and in START. Check this... you must have 12 volts during START on terminal B and + side of coil. 

 

Don't you worry, we'll get this going.

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I have a black and green wire in that area too. Should that be going to anything?

 

 

Mike, I don't get anything during cranking from the b pin to the + terminal.

 

Yes, you must have power during cranking. Test that Black/Green wire for power during START.

 

My wiring diagram shows the START signal wire being Black/Blue.

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So to explain in more detail - right now I have the black/blue and black/white wire connected to the + side of coil. I have a wire going from the + side of the coil to the b pin of the matchbox. I have a wire going from the - side of the coil to the c pin of the matchbox. I get no spark

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EIwiringtocoil.jpg

 

...The B terminal should have 12 volts with ignition ON and in START. Check this... you must have 12 volts during START on terminal B and + side of coil. 

 

Don't you worry, we'll get this going.

 

 

Yes, you must have power during cranking. Test that Black/Green wire for power during START.

 

My wiring diagram shows the START signal wire being Black/Blue.

 

Test for 12 volts.

 

 

 

Is the plug in the back of the ignition plugged into the harness?

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OK update with figures. In the ON position, bother the + and - sides of the coil have 12 volts. Both the b and c pins have 12 volts as well. These are all to ground figures.

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OK during cranking my figures are: from the + side of the coil I go to about 9.5-10 volts. On the negative side same thing. On the b pin of the matchbox I go down to 9.5-10 volts and on the c side it jumps up and down.

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I think that was the problem. Cleaned the back of the module and got spark. Thank you Mike for helping me out. Fired her up and she sounded incredible.

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