1984 90hp Merc No Spark

Thrillbilly

Recruit
Joined
Oct 13, 2014
Messages
4
I pulled the cover off the boat this year and the ignition switch was corroded and needed replacement. I bought a [FONT=Arial, sans-serif]Sierra International MP41000 Push To Choke Marine Ignition Switch. Upon installation everything worked, but I have a no spark condition. The choke and starting circuit work but I zero ignition. I have replaced both the stater and the trigger. I replaced the trigger because I thought it was causing the condition, and the stater because the wiring was corroded.

I'm at a complete loss. I can't believe both power packs went bad at the same time, and everything else is either new or testing good. The battery is strong and is cranking the engine more than 300RPM.

I'm open to any suggestions or further tests as to why this thing has no spark. Thanks in advance.
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Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Unhook the black/yell wire on switchbox and retest(plug wires on spark tester in case it starts)
 

Thrillbilly

Recruit
Joined
Oct 13, 2014
Messages
4
So it ran last week, and now I'm back to a no spark condition....What could cause a short to a rectifier? Could that be the new cause of the current no spark? The currently installed rectifier is passing the test. Kill switch circuit is good, could the "M" wires at the switch be crossed and allow it to run last week? Very frustrated. About to throw in the towel on boating this year.
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,657
swapping the "m" wires will not change anything.


my guess is the new ignition switch may be bad,internal short.

put the old one back in and see what happens.
 
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