Rectifier Question

[krawczmwk]

I have an 84 50hp merc. I did a continuity check on the rectifier. When I checked the continuity from ground to terminal A, no continuity, when I check ground to termina C, there was continuity. My question, the manual says that the test indicates that there should not be continuity to either. Given my results, does this indicate a bad rectifier. I have had a problem with the engine running fine in neutral but when I go WOT, it has very little power. Could the bad rectifier create this problem? Any help would be greatly appreciated.

 

[Laddies]

Re: Rectifier Question

Yes a bad rectifier can cause running problems, To test for that problem remove the 2 yellow wires, tape them off and test run the engine on the water, free reving a engine proves nothing and can damage the reed valves. I can't under stand your test so here's the test from mercury it either passes it or not.

 

[krawczmwk]

Re: Rectifier Question

Thanks Laddies,

I will give it a shot and let you know.
mark

 

[krawczmwk]

Re: Rectifier Question

Hello Laddies, I hope you check this post again. I used a fluke 111 and then used my old analog multimeter. Here are the results of my tests with a fluke 111 and the analog meter. Not sure why the different results other than the fluke may have more stringent resistance settings.

step 1. Fluke
Ground to terminal A - no continuity resistance 2.96
Ground to C - Continuity resistance .6

Analog
Ground to A no continuity
Ground to C contnuity


Step 2. Fluke
Ground to A - no continuity resistance OL
Ground to C - Continuity Resistance .6
Analog
Ground to A continuity
Ground to C continuity
step 3. Fluke
Terminal B - A no continuity resistance 1.97
Terminal B - C no continuity Resistance 1.7
Analog
B to A no continuity
B to C no cont

step 4. Fluke
B to A - no continity OL
B to C - no continuity OL
Analog
B - A continuity
B to C continuity


I also checked the DVA with my analog meter and adapter

Stator
Blue - Blue white within range
Red - Red/white within range

Trigger -
Purple - white within range
Brown - Black no voltage

swithbox
green - ground within range
Green/white - ground within range
White - ground no voltage
Black - ground no voltage

It looks like the trigger may be bad based on these results.

Coil - same results as switchbox.

Do you think the rectifier and trigger can be bad. I really appreciate your help.
mark

 

[krawczmwk]

Re: Rectifier Question

Well the saga continues

I got the flywheel off. I removed the stator and as I was removing the trigger, I noticed that the black wire from the trigger to the switchbox had previously been spliced. I bought the boat about 12 years ago. The trigger wires are in a plastic casing from the trigger to the switchbox. I carefully opened the casing with a knife to check the condition of the wire and found that the black wire plastic coating was almost powder at some points and that the strands had almost detrioated to nothing at some points. the other wires are in good shape as far as I can tell. I followed the black wire to the trigger and found that at 4 -5 inches from the trigger the wire was in pretty good shape. There was very little corison at that point. 2 questions, what would cause this , second question, should I replace the trigger or splice new wire. The black to brown cable had a OL for resistance and no voltage during a DVA test. I will check the resistance tomorrow to see what it reads. i'm worried the wire maybe corroded to the trigger and shorting in the trigger but I hate to spend money if the trigger is still good.
any thoughts?
thanks
mark

 

[Laddies]

Re: Rectifier Question

One AC side of the rectifier is shorted, If it is possibly to spice the trigger wires in a workman like matter ad they then ck OK go for it, The older mercury wiring just deteriorates over time.

 

[krawczmwk]

Re: Rectifier Question

Hello Laddies,

Not sure you will check this but my efforts to fix are not working. I replaced the rectifier, repaired the wire, but when I used the fluke and DVA to test voltages on the stator and trigger again. This is what I found
Stator blue to blue/white with wires disconnected - 5 volts
red to red/white with wires disconnected - 50+ volts

Trigger Purple to white over 5 volts
Black - Brown - no volts.

I guess I somehow fried the electrical system. I guess my next option is a new stator and trigger. I am not sure about the switchbox.

Any ideas?

mark

 

[Laddies]

Re: Rectifier Question

Mark, that's not the right test procedure for testing the stator and trigger here's the test from CDI try it and see if that helps

 

[krawczmwk]

Re: Rectifier Question

Laddie, Thanks for keeping up with the thread. I realy appreciate your help. my engine is a 85 50 hp 4cyl. I'm using the CDI toubleshooting guide for the 4 cylinder. I'm really stuck. I'm not sure what would cause the rectifer, low speed stator coil and the brn-black coil on the trigger to go bad at the same time. I thought the trigger wire problem would fix my problems, but no luck. my original problem was that I had full power in neutral, but would only go 10 mph at wot. I rebuilt the carbs and pump, but same problem. it was hard to start, but it started. The very last time I started the boat, it had been sitting for a couple months and I hooked my battery charger to it. I may have screwed up, I set it to the starting setting on the charger, high amps and hooked to my battery. it started, ran rough, stalled out and has not started since. I'm guessing I fried something. I bought a new battery before I started this round of troubleshooting. The strange thing is, it was an old battery charger and when I tried use it last week, it was bad to and had to replace. My latest question (thanks for your expertise and PATIENCE) would the 20 amp fuse in the starter wiring have blown if battery charging setting on the battery charger was set to high? Also, is there a wiring harness on a 50 hp merc? Is it in the control box that has the key? Thanks again for your help.
mark

 

[G3Joe]

Re: Rectifier Question

Just as an FYI,
I have almost the same motor(83), it had the same problem. When I pulled the flywheel off, all of the wires just coming off the base of the trigger AND stator were showing missing bits of insulation and powdery residue with corroded wires. I bit the bullet and replaced the trigger, and stator, then the switchbox because it too was bad, then said, oh well, may as well purchase two wiring harnesses' and a rectifier. Let me tell you, that motor fired up and purred (and charged) after that massive cash infusion. Just hate the external trim motor. Wish it had the newer style of integral tilt trim unit. Oh well, time to pick up some overtime as now I am broke.

 

[Laddies]

Re: Rectifier Question

Mark, sorry about the 3 cyl post. It's seldom there is that kind of damage but if I had it I would check the black/yellow wire (ground off) for voltage, a short in the ign. switch could let 12 volts come back to the engine on the ground off wire and that would definitely do that kind of damage in a hurry. The ign. system is completely separate from the battery and anytime 12 volts to it you stand a chance of damage, many systems are damaged by someone arcing with a screwdriver. The reason a shorted rectifier will cause a engine to miss is the short causes the stator to overheat and that will effect both systems. I see no reason the charger would blow the fuse if it were hooked to the battery or solenoid and ground, however a short in the switch or it's wiring would blow the fuse.

 

[krawczmwk]

Re: Rectifier Question

thanks for the info. Question, what wiring harnesses did you replace? Where did you buy them?

 

[krawczmwk]

Re: Rectifier Question

Thanks Laddies,

I'm not sure I understand the test to run on the black/yellow. Should I disconnect it from the switchbox and have the red lead on the b/y wire and the black lead to ground and do a voltage check? I'll try run the test tomorrow. I have had some strange resistance readings based on the CDI guide. I will use the fluke and post them tomorrow.

mark

PS. I have family up in Port Austin Mi. Is that anywhere near you?

 

[G3Joe]

Re: Rectifier Question

I used the crowler marine website to get the part number. Of course it was NLA (no longer available) but when i googled the part number I was able to pick up what I needed from E-basic power.

http://bpi.ebasicpower.com

(I have ZERO connection to that site BTW)

There is some discussion about if their stuff is inferior or superior to OEM, I will post on here when/if it fails. Personally, my wallet still hurts from that switchbox but OEM is much higher. I went the cheaper way.

You're probably going to want the wiring diagram I posted on another thread.

http://forums.iboats.com/showthread.php?t=462463

Whoa look at the time...

nite all

 

[krawczmwk]

Re: Rectifier Question

I was checking the CDI electronics site for the switchbox. I'm worried that since the stator and trigger got fried, the box may be bad as well. The test sounds like the test that you suggested in your post. My question, is the kill wire referred to in the cdi procedure, the black/yell wire the kill wire? Thanks again for any suggestions.

Disconnect the kill wire(s): Connect a DC volt meter between the kill wires and engine ground. Turn the ignition switch on and off several times. If, at any time, you see DC voltage on the kill wires, there is a problem with the harness or ignition switch. Battery voltage on the kill circuit will destroy most ADI type switch boxes.

 

[krawczmwk]

Re: Rectifier Question

Just to close out the thread. After using the DVA, I found the trigger, stator, rectifier and switchbox to be bad. I replaced all and the engine cranked on the first turn. Just an fyi, be very very careful not to short out the ignition system or you may end up doing the same thing I have had to do. Learn alot about boat motors and spend some time doing it yourself and save a ton of money.

 

[krawczmwk]

Re: Rectifier Question

One last note, thanks to all that contributed to the tread. I could never have done any of it without this site.