No Spark Where did high voltage go

[mckinneyra]

"1989 Mariner 150hp problem wi

"1989 Mariner 150hp problem with losing spark. I recently bought the boat, and the prior owner told me of this problem. The boat had 2 batteries and 2 150 Mariner outboards. Port engine started and ran well. Starboard engine turned over weak. Thinking he had a weak battery he put battery switch from the "A" position to the "AB" position and tried to start engine. It fired a moment then died, loss spark. He said the technician found a bad cell in the battery and that he also had lost his stator winding. Stator winding was replaced and ran ok. I come into picture and buy boat and on the sea trial (while still at the pier) the same engine turns over slowly and will not start as had happened before. He again thinks that engines battery is weak so he puts switch in "AB" position...it starts and runs rough for about 30 seconds then dies. Upon checking with spark tester, NO SPARK. Lost high voltage again. Have not checked to see if Stator is blown yet, So now it sits waiting for me to troubleshoot. There is no high voltage to any cyl of this engine. Any ideas on how to proceed???"

 

[galamb]

"That indicates a problem in t

"That indicates a problem in the ignition system that most likely has nothing to do with the battery.

The two issues are almost certainly unrelated. There could be a short somewhere in the charging/starting system that is giving the battery a hard time, but that has nothing to do necessarily with the ignition problems.

These motors are totally self contained as far as power for the ignition. If you had eaten enough "wheaties" to pull these over with a rope start, the motor would run perfectly without a battery.

In this case it is possible that the stator is toast. The stator itself, which comes as a "unit" is actually made up of three separate components - high speed coils, low speed coils and charge coils.

If it's gone "flooey" it could have taken out some of the coils required for the ignition and the charge coils which are giving the battery a hard time, possibly grounding it out and draining the power.

That comment from "some guy" who said they replaced a winding sounds very "fishy", you don't replace individual components of the stator - the whole thing is replaced as a unit.

You can start with the quick and easy stator test - disconnect all the wires from the stator to the switchboxs (should be 4 of them) and the two yellow wires that feed the regulator (or rectifier).

You are simply looking for continuity between similar wire - so depending on the exact stator you have, between yellow and yellow (charge bobbins), and then the two solid colours (normally blue and red) and then the two with tracers (blue/white and red/white).

Both the red and red white should also have very minimal resistance to the black wire coming from the stator.

The blue is the low speed and red the high speed bobbins (with the solids feeding one switchbox and the (tracers) feeding the second switchbox)- the ohm test checks both simultanously - you are looking for continuity.

If any of the tests comes up as a flat line, it's most likely dead - if it appears to have connectivity (with some resistance) then the stator must be tested on a DVA meter to determine if it's putting out the correct voltage or not."

 

[mckinneyra]

Thank you Graham. That reply

Thank you Graham. That reply makes so much sense. I will make the 100 mile trip to the boat in the morning with my test meters and follow your diagnostics. Will let you know how it came out. Very Grateful!!