CV30ELD fuses blowing....rectifier suspect

[JD]

Out on the water w/ My 1990 Yamaha CV30ELD the other day and the starter and choke switch failed. the 20amp in-line fuse was blown and concurrently blew the replacements I put in....

Disassembled the ignition coil components and followed the red (+) fused lead to the rectifier. Ohmmeter on the rectifier showing continuity between the red lead and gnd. Seems suspect to me as rectifier is failing the test protocol in my Clymer manual.

Anyone have experience/advice on this one?? Motor cranks and runs fine w/ pull rope. Does rectifier replacement sound like the right choice. I'll also go through the CDI magneto coil tests and the ignition coil test. I am assuming the CDI unit is OK as the motor runs good.

thanks in advance

JD

Gearing up for spring fishin in NC

[boats.net]

You have short in the wiring, could be in the key switch, main harness or the engine.But not in the ignition, the rectifier could be but probably not. Read the manual for testing rectifier, you have check continuity both ways to check diodes by reversing test leads, you should have continuity one way none when leads are reversed.

[JD]

Rectifier continuity test is failing:

Black (GND) + (red on ohmmeter) =
Green-X
Green-Continuity
Red-Continuity

Black (GND) - (black on ohmmeter) =
Green-X
Green-Continuity
Red-Continuity

I see from the wiring diagram that the 2 green leads go to the lighting coil in the CDI magneto, I also noticed that one of the green leads at the rectifier was corroded (green and foul) I had to replace the barrel connector on the lighting coil lead side.

Another situation, the fuses were still blowing w/ the main harness connector disconnected (prior to disassembly) thus indicating that the key switch is not at fault. I will test the switch as well.

Also, will start testing lighting, pulser and charge coils. Wondering if any are damaged now. I believe the rectifier got fried by open circuit on the one corroded green lead, as indicated in the manual.

Thanks for the advice, I'll post more results of my progress. I have a new rectifier waiting at the parts shop, but I want to go thru all I can before installing...

I also pulled every bullet connector and put in some dielectric grease on the male/female parts. (I generally do a light spray down of the engine interior during flush as I'm in the saltmarsh constantly)

JD

[JD]

Note: my CDI unit is a 7 lead, not a 9 lead as specified in the wiring diagram. Looks like I have a charge and pulser coil in the CDI magneto and no lighting coil is present.....the pulser coil is showing approx 130 ohms and the charge coil is showing approx 14 ohms (cold) they both swing when you rotate the flywheel....I am assuming the cold temp and/or my meter is giving false readings.

Also, I can't get any accurate readings on the CDI unit w/ my elec. (no needle) ohmmeter.....assuming she's ok.

[JD]

disregard above about no lighting coil, yes there is lighting, pulse and charge coils somewhere buried underneath that flywheel....

OK, didn't get much response on this one, but Eureka!! Problem solved. It was the pinche rectifier that failed. So, $58.35 later w/ new rectifier in hand, I compared continuities on the old and the new and sho nuff that 1990 rectifier was skint back...

In w/ the new and now I got, spark, compression, and fuel/air mix and the scalded dog that she is runs like a top. Oh and the fuses don't blow and the starter and choke function as well.

Swear I'll never take my boat to a mechanic, but now I need a bigger hole in the water w/ more HP. Then again I run in 6" of salt marsh at 30 mph so maybe I'll stick to the inside......