115HP Tower of power spark only on 2,3,6

[ROADDOG]

115 TOP Serial number OA729167. Motor came with the boat, I don't know the history. I do know even compression at 125 on all cylinders, I replaced floats and needles and cleaned carbs. Motor stalls at idol and will stall going into gear. I could feather the RPM and keep it running, seemed ok at WOT and didn't sound like its missing or surging. I had a mechanic look at it at the dock and he says spark only on 2,3,6. He swapped plugs and wires, no change. He couldn't get it to start at all. I didn't have any problems starting it last weekend. I have read of no spark on all even or odd cylinders or spark missing on one cylinder but not a mix of both. Any ideas on where to start?

 

[jimmbo]

Get a spark tester and check. Should jump a 3/8” gap. From there you can start your troubleshooting

 

[ROADDOG]

jimmbo, I assume he used spark tester and determined spark only on 2,3,6.

 

[Chris1956]

I think I would double-check spark, and verify the cylinders that don't have it. Maybe it is some combination of coil and trigger issue?

 

[jimmbo]

jimmbo, I assume he used spark tester and determined spark only on 2,3,6.

Fine, do what ever you want

 

[ROADDOG]

I just picked up a spark gap tester. I will confirm if there is spark/no spark and can jump 3/8 gap on all cylinders this weekend. Assuming its as he said spark on 2,3,6 and nothing on others, what's the next step? see if switching boxes around produces same or opposite results?

 

[ROADDOG]

Confirmed no spark on 1,4,5. Checked with DVA meter and zero volts at coils and at switch box on 1, 4, 5. disconnected black/white joining the 2 boxes and same results. Tested the trigger and stator and the readings are inspect. Ordered 2 new CDI boxes.