90 hp Mariner no spark

[acclark]

I have a 1992 90hp 3cyl. Mariner with the low oil warning module. There is no spark on any of the cylinders. It ran great last time was run - about 1 month ago.<br /><br />Resistance checks on the charge and trigger coils are within specifications. DVA checks on the charge coil and the switchbox stop circuit are also within specs. DVA shows no readings on all ign coil primaries.<br /><br />Disconnecting the blk/yel stop wire from switchbox has no effect (get same readings as above)<br /><br />Would there be any sensors (low oil or temp or...) that might be preventing fire even when the blk/yel stop wire is disconnected?<br /><br />Resistance checks are also good on all the ign. coils. The spark plug wire from the #1 coil was found to be making a bad connection to the coil (corrosion), but the other 2 coils were fine. Would a bad spark plug wire connection to the #1 coil cause the other 2 coils not to fire?

 

[emckelvy]

Re: 90 hp Mariner no spark

Sounds like a bad switchbox.

 

[acclark]

Re: 90 hp Mariner no spark

Would a bad switchbox still show the correct stop circuit DVA voltage? After cleaning all of the old gunk and grease out of the sockets where the spark plug wires plug into the coils, and making sure all of the spark plug wire connectors were making good connections with the wire, the motor started right up and ran great for the rest of the day. The next day, there was no spark again, showing all of the same symptoms from the last post. All of the same resistances and DVA readings from the last post were obtained again. <br /><br />Would there be any reason that a bad ignition coil or spark plug wire (or spark plug, for that matter) might cause the switchbox to not fire any of the coils?

 

[achris]

Re: 90 hp Mariner no spark

It's very unlikely that a bad coil, lead or plug would shutdown the entire switchbox.

 

[Elmer Fudge]

Re: 90 hp Mariner no spark

No spark on all three plugs says it's most likely to be a bad switch box or a bad stator

 

[acclark]

Re: 90 hp Mariner no spark

I have now realized that it seems the motor has good spark (and will even fire up and run briefly) when it is cold. After about 10-30 seconds of spark/running, the motor will shut off and then the no spark conditions stated before occur. It is most likely that messing around with the spark plug wires and cleaning off corrosion had no effect - it just gave the switchbox a chance to cool off. Therefore, a bad switchbox may likely be the cause - I am ordering a new one.<br /><br />The stator was just recently replaced (about 6 months ago with a CDI aftermarket unit) because the low speed charge coil was causing very difficult starts.<br />Could a bad trigger coil or bad ignition coils cause a switchbox to go bad? I would hate for the new switchbox to die from the same thing that caused the old one to die. Or can switchboxes just go bad for no apparent reason? Resistance checks show the ignition coils are all within specifications and resistance checks show that the trigger coils are all within specifications (one was right at the lowest value given for the acceptable range). The DVA readings from the trigger coils were all about 2V.