Update : Spark problem, 1988 90 hp

[achris]

Hi Guys,<br /><br />Have a bit of a curly one.<br /><br />1988 90 hp Johnson. Intermittent spark. But if I disconnect one of the power packs the sparks from the other are strong and consistent. Only if I have both packs connected do I get weak and/or no spark. When I have no spark it's both coils on that pack.<br /><br />How do I determine which pack is causing the problem? Is it a pack problem? Could it be the stator? (Hope not).<br /><br />Yes, I have tested it with the control box disconnected to rule out the ignition switch and kill button, and with the kill wires disconnected for the pack connectors.<br /><br />Thanks in advance.<br /><br />Chris.............

 

[fireman57]

Re: Update : Spark problem, 1988 90 hp

Just guessing it sounds like you might have a bad ground. I don't have a manual for your engine, but you should, but if you can try swapping the packs and see if the trouble follows.

 

[achris]

Re: Update : Spark problem, 1988 90 hp

Fireman,<br /><br />Thanks for the reply. Checked all the grounds, tightened a couple but the problems is still there.<br /><br />The problem is with one of the packs, but disconnecting either will cause spark in the other to be good.<br /><br />Chris.............

 

[Dhadley]

Re: Update : Spark problem, 1988 90 hp

The isolation diode is bad in the pack. Most times its just one pack that kills the other side. Real confusing if youve not seen it before. <br /><br />Just for kicks, unplug the big red cannon plug (main harness connector) and check spark again. Just check spark -- dont try to start it. You wont be able to shut it off or flood it with the key. Just jump the solenoid and check spark. I'm guessing you'll have the same result but lets check it anyway.

 

[achris]

Re: Update : Spark problem, 1988 90 hp

Thanks Dhadley,<br /><br />Yep, did that and yep, same result.<br /><br />I understand what you're saying about the isolation diode. How do I determine which pack is bad? Just swap one with a good pack and if the problem's gone I got the right pack?<br /><br />Chris.......

 

[Dhadley]

Re: Update : Spark problem, 1988 90 hp

Usually what happens is that you lose spark on 2 cylinders (one side). The isolation diode on the "good" pack is bad killing the other pack. <br /><br />Are you getting consistant good spark on one side but inconsistant or no spark on the other? Or does both sides lose spark?

 

[achris]

Re: Update : Spark problem, 1988 90 hp

I have both. Sometimes lose spark on both sides, sometimes only on one side. But when I have spark on all cylinders, it's weaker than if I disconnect one or other pack.<br /><br />Chris.........

 

[Dhadley]

Re: Update : Spark problem, 1988 90 hp

Well, it looks like we might have to try 2 packs. Or either put one of these on a known good running motor. <br /><br />Is there a chance that the wire between the 2 packs is prtialy shorting to ground?

 

[achris]

Re: Update : Spark problem, 1988 90 hp

Is there a chance that the wire between the 2 packs is prtialy shorting to ground?

Checked that too. Don't have another 'good running engine' as a test-bed. Nice thought though. Usually only work on black (or grey) engines or sternies.<br /><br />I'll get another pack tomorrow and try it out. Could I damage a good pack with a bad one?<br /><br />Chris..........

 

[Dhadley]

Re: Update : Spark problem, 1988 90 hp

I dont know for sure but I dont think so. Thats what usually happens when one side goes out. The new pack is put on that side -- still no spark then the old pack removed is put on the "good" side and all works well. So I'd guess that it'd be OK.

 

[achris]

Re: Update : Spark problem, 1988 90 hp

Thanks for your help Dhadley. I'll let you know the outcome.<br /><br />Chris..........

 

[achris]

Re: Update : Spark problem, 1988 90 hp

Hi all,<br /><br />Thanks for the help. I put a new pack on the starboard side and she runs like new. I owe you all one. <br /><br />Chris..........

 

[Dhadley]

Re: Update : Spark problem, 1988 90 hp

Great! Thanks for the update!