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| 86' Mercury 115 cyl. 6 has no fire |
| Author |
Message |
    
Graham Lamb
Senior Member
Username: galamb
Post Number: 5701
Registered: 05-2007
| | Posted on Saturday, July 18, 2009 - 04:57 pm: | 
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Could be a bad stator taking out the switchbox.
You say they check out fine - did you have them DVA tested or just relying on a standard ohm test? |
Wild Bill
New member
Username: footprint47
Post Number: 3
Registered: 07-2009
| | Posted on Saturday, July 18, 2009 - 05:38 pm: |
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i used a DVA |
Graham Lamb
Senior Member
Username: galamb
Post Number: 5706
Registered: 05-2007
| | Posted on Saturday, July 18, 2009 - 07:12 pm: |
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That is a weird one.
Since you have already toasted that box why not put it to some practical use and swap around the leads and test the trigger in a practical way.
Your number 6 is toast, so move the number 6 trigger lead to the number 4 spot on the box and feed the number 6 coil from the number 4 spot as well. (this is how I test Prestolite ignitions with "phantom" problems)
Rewiring like that should leave your number 4 cylinder "dead", if you smoke number 6 again, the trigger is throwing a wild pulse to number 6 and toasting some part of it's circuit (scr, blocking diode, whatever) - (understand what I'm getting at here? - the switchbox is stupid, it doesn't know or care what is feeding in or out of it, you could wire it upside down and when it gets the trigger at whichever connection, it will release power from that capacitor to whichever plug coil is connected to it)
If it doesn't fry it in a short test (ya, it will idle like crap for a couple minutes) you may simply have a ground problem from that box. But if it does, then the trigger is the problem.
Although if it is the ground I would have expected it to take out more than a single capacitor... |
Wild Bill
Member
Username: footprint47
Post Number: 4
Registered: 07-2009
| | Posted on Sunday, July 19, 2009 - 11:43 am: |
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i moved #6 to #4 now #4 out
#6 is working |
Graham Lamb
Senior Member
Username: galamb
Post Number: 5726
Registered: 05-2007
| | Posted on Sunday, July 19, 2009 - 12:50 pm: |
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Ok then, so #6 trigger, and cylinder 6 fire when moved - so definately the box again.
Either you got a bad box after replacing the last one (kinda high odds that exactly the same capacitor would toast), or you have a ground fault or a cross feed somewhere in that circuit.
I would pull the flywheel and closely inspect the all the wires for rubs/pinches etc. Remove, clean and retighten all the ground contacts and even go so far as to replace the number 6 coil, wire and spark plug (plug may not be grounding properly sending a 55,000 volt surge back at the switchbox from number 6) incase the problem is somewhere there.
Something is frying that single circuit and in this one case, simply swapping out parts is probably the fastest way to fix it... |
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