Rectifier wires

[Besegen]

Does it matter which yellow wire connects to which terminal? 1975 85 HP evinrude. There appeared to be no difference between the 2 yellow wires on the new rectifier. I went by where they came out of the back on the old and new. I've been starting and running the boat for four straight days now no problem. After putting the new rectifier on a bit ago it cranks but won't try to fire at all. Not sure why it would affect that when it started fine with the bad one. But its the only thing I did.

 

[Besegen]

Re: Rectifier wires

I just did both inductive and inline spark tests and I am getting no spark to any of the plugs since changing the rectifier. It does seem to try to fire for one quick round the first crank after sitting a bit then nothing until it sits for a few minutes again.

 

[Crosbyman]

Re: Rectifier wires

wait for more comments but the 2 yellows should carry AC to be rectified (possibly regulated) via a 4 way bridge diode circuit
of the rectifier function, the output being DC + voltage to charge the battery and other chores

Being an alternating signal , it does not matter which yellow goes where as long as we are taking about the INPUTS to the rectifier/regulator .

Each yellow will alternate (swing) between their + and- peaks and be individually routed out to the "rectified" RED power out (DC)

As to not starting....can't say have to tried the BAD rectifier since you say the engine fired up with it ?? How did you arrive at he conclusion the rectifier was bad ??

 

[Will Bark]

Re: Rectifier wires

Make sure the battery connections to the starter are very clean and that the starter can spin the engine a minimum of 250/300 RPMs below that and you can get no spark. Rectifier should have nothing to do with starting the engine; may want to get the battery load tested at an auto parts store. Good luck

 

[Besegen]

Re: Rectifier wires

Thanks for responding guys. I didn't think it should matter. If I understood you correctly Crosbyman, no I have not tried putting the old one back on and trying. I did think about it but it was getting late and I decided to just wait and see what was said here and trying it in the morning if still need be. The one other thing I did do, which I'd forgotten about, was open the inline fuse that was running across near the rectifier just to get it out of the way while I changed it. Would that affect it? The fuse looks good but you never know with fuses. I rechecked it and it when I put it back together it seems like one end of the fuse is kind of loose in there. I may have to look at that more tomorrow.

It was cranking and running fine just earlier before I changed the rectifier and messed with that fuse. It still cranks strong exactly like always, just won't fire spark.

I determined the rectifier to bad per the resistance test mentioned on this forum and my manual. I suspected it initially because my tach was not working. It always sat around 1100-1200 rpm. I don't know if it was due to it being bad or not but I also noticed the other day that it got hot to the touch pretty quick when the motor is running.

I will switch back to the old rectifier tomorrow and see what happens, check that fuse and inline holder over and go from there I guess. Thanks for the help.

 

[F_R]

Re: Rectifier wires

Fuse has nothing to do with spark / no spark. But the starter wouldn't run if the fuse was bad. The ignition system does not operate off the battery, it generates it's own electricity.

 

[Besegen]

Re: Rectifier wires

Good point, thank you. And I know that. Don't know what I was thinking. just brainstorming everything I touched between spark and no spark I guess. I don't see what it would have to do with it either but going to put the old rectifier back on this afternoon and see what happens. I'm stuck on thinking it has to be something I touched because it worked before then not after. If the old doesn't work either now though I may have to change my thoughts. Could well be just pure coincidence with something unrelated.

 

[Besegen]

Re: Rectifier wires

I put the old rectifier back on and still got no spark. I found my way to the CDI troubleshooting and read through that process. Decided to head uptown to get parts to build a DVA adapter so I could follow the process but first stopped to try removing the yellow rectifier wires to see if there was spark per one of the steps. It worked. I then hooked the yellows back up one at a time cranking it up between. It worked every time even with it all hooked up again.

Took the old rectifier off and went through the same process with the new one. Fired it up with just the red first, then one yellow then both. It worked. Put everything back together and headed out to the lake. We spent about five hours out there motoring around and fishing. Everything worked fine. I have no idea why it wouldn't give spark with either rectifier at first until I had disconnected the two yellows and tried with just the red on the old one. But it did. Thanks for the help guys. Hopefully there isn't something else sporadically going wrong that's going to hit me in the middle of the lake later, but it seems fine now.

Oh, the tach still isn't working though. I've been through all the connections for it and they are correct and good. Does this leave me with a bad tach? or is there anything else I should test for it. What I've seen to this point is to test the rectifier, if its good and the wires and connects are good then its the tach. Thanks again.

 

[Crosbyman]

Re: Rectifier wires

my power pack on my merc classic would do silly things like that .... go no go go no go .... stay close to home for a few fishsing days and... bring a kikker just in case

 

[Besegen]

Re: Rectifier wires

Yeah, that's what I was preparing to start testing per the CDI guide. Power pack and timer base...kind of had my eye on the power pack. When its doing that...go no go no go no...stuff will it the testing show it bad when its in a running fine phase or does it need to be in the middle of acting up? I know its not a car but once with my old charger we fought a coil problem for nearly two years because it would never act up when we could test it. Coil was the first suspect and I'd replaced it already but had gotten a bad new one too. Took forever to catch it though.

 

[Chris's CVX16]

Re: Rectifier wires

FWIW I've smoked 2 rectifiers in the 2012 season. They don't like it when rough water causes loose battery cable connections to open up. The last one I melted all the resin from the inside of it all over the side of my block. Luckily I have a real good multimeter and while the first one was failing I did some looking at what those wires really do.

It seems that the yellow wires each carry about 6 volts AC when the engine is running at idle. They go into the rectifier to hit the diodes there and come out as 12V DC on the red wire. Its a real simple device they just don't like it when there is no battery on the other side to balance the load.

As far as the tach goes. When my rectifiers went bad my tach started acting odd then eventually stopped working all together. The tach works on the frequency of the AC coming off the grey tachometer lead, which comes off of one of those yellow leads at the rectifier. For your motor I think that is the #6 & 7 connections at the terminal block on your motor. Those 2 terminals should be jumped together since 3 wires are needed for that circuit.

 

[Besegen]

Re: Rectifier wires

Hi, Chris. Thanks for that info. The boat is still going fine. I assume I must not have had a good connection for whatever reason when I replaced it the first time. Today I went ahead and disconnected and cleaned all the connections and tightened everything up just in case.

The tach still doesn't work though. It always seemed to sit around 1100-1200 RPM before I replaced the rectifier. Now it sits at about 800. My buddy who backs the boat off the trailer says when he fires it up the first time it pops straight up to high noon then falls back to 800 where it sits after that. I haven't seen that yet, I never see it move...even when I tap it around or something. Even disconnected from any power. I checked the #6 and #7 terminals and they are jumped already. I took them off and cleaned them to be sure. I followed and checked all the wires and connections. Everything seems good, tight, and clean. Turned the setting button around a few times and put it back to the 6 pulse position and still nothing. I assume its just bad unless someone has other advice.

 

[F_R]

Re: Rectifier wires

Is your battery charging now? If it is charging, the tach should work, assuming it is properly connected. But if charging and no tach reading, I would suspect a bad tach. ---OR---the tach is not getting 12V input from the ignition switch in "run" position (purple wire). ----OR--- the tach is not grounded (black wire). ----OR---- it is not getting a signal from the alternator (grey wire).

Last ditch effort before buying a new one, connect it directly to motor and see if it works. That bypasses all the forward wiring, etc.

 

[Besegen]

Re: Rectifier wires

I had meant to check the charging last time we went out but we ended up rushing to load up due to lightning storm moving in and I forgot. Tried to take it out again today and it was first on my to do list but once again the boat wouldn't fire up. Brought it back home and tried on muffs and no spark. Checked battery, tight connections (just cleaned all connects yesterday), tested rectifier (tested good), tried removing the two yellow wires just in case (is what ended up working last time) and nothing. My gut says its the power pack acting up like Crosbyman says his did.

We gave it up and went shore fishing. Came back home about six hours later and I just had to try again on muffs. It fired right up. Annoying.

Thanks F_R, I've been over the wires and the red and ground are fine. I'm not sure how to go about testing the grey. I like the "hooking it up to the motor" plan. Will try that this week. All for naught though if I don't get this "works one day not the next" spark problem figured out.