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2005 BF90A Ignition issues.... Need expert advice....

D

dtoole

Regular Contributor
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Can any experts tell me what these wire do. Input values/output values? I have weak spark across all cylinders and no spark on cyl 4. All that I can come up with is that I have an issue with the boat side harness. I have disconnected the harness and want to start the engine eliminating the boat harness before spending money on a CDI box. I have swapped coils,wires,plugs everything that I can think of to pinpoint this problem. I have a weak spark on all cylinders (don't know the source). 1,2 and 3 will light up but #4 will not. #4 will light up a timing light but not the plug. I have been troubleshooting for several weeks now (bout to lose my mind). All comments welcome... Need to know what wires are needed to run the engine independant of the boat side harness. 2005 BF90A. 12 volts to bl/y to power the CDI and ground to bl/r to stop? Bl to ground? Is anything else needed?
 
Hi,
Not the expeet you request but just wondering if you swapped plug 4 with any of the others for a "re-check"?
 
You just need the two wires you mentioned the black/ white to pos for crank. Your issue is strange because 1 an 4 should fire together from the same coil. It looks more likely to be a bad ground, or low voltage into the cdi. The fact that you have weak spark means your cdi is fine as are the pulsar coils which leaves low voltage in.
 
iang6766 said:
You just need the two wires you mentioned the black/ white to pos for crank. Your issue is strange because 1 an 4 should fire together from the same coil. It looks more likely to be a bad ground, or low voltage into the cdi. The fact that you have weak spark means your cdi is fine as are the pulsar coils which leaves low voltage in.
Click to expand...
I agree with the strange part 100%. I did a little more testing yesterday. I bought a new set of plugs just to rule out the stupid. No change. I then disconnected the black/red kill switch wire. No change. I then spliced into red wire and the yellow/green, checked voltage while running. 13.4 volts. I still need to check the black/yellow when running. My first thoughts were low input voltage, but I'm not seeing this. Now I'm thinking about the internal components of the CDI. 12 volts is delivered to a step-up transformer then stored in a capacitor to be released by a signal from the pulse coil ?? If the capacitor or the transformer is malfunctioning, it could possibly show the proper voltage to the coil input with the DVA meter but fall out under load. Voltage present but current not sufficient ???
 
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