1976 85hp Johnson and 1975 85hp Johnson Rectifier Wired Different 5

jiju1943

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photo229058.jpg While hooking up a tachometer on our 1975 85 hp Johnson, I noticed the rectifier hot wire was just about shot. I took the rectifier off the 1976 85 hp Johnson that I have for parts. The two engines were wired just a little different. The same color wires, just in a different place.
The 1975 the first three wires from the left, red- yellow - yellow with stripe
The 1976 the same wires from left red- yellow with stripe- yellow

My question is, if the wires are connected to the same color to color , no matter where they are on the block, would tht mess the rectifier up if I cranked it?

First picture is 1975
Second picture 1976
 

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Vic.S

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So long as the colours are matched up you'll be OK

If the +ve ( red) wire shows signs of overheating then a likely cause is that the battery has been connected with reversed polarity. in which case the rectifier will be fried. Check the positive wiring in the engine wiring loom for signs of heat damage.

Take care not to connect the battery incorrectly. Its instant death to rectifiers!
 
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Faztbullet

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The 1976 rectifier never worked as someone hooked it up incorrectly, test it before you change it. They have the red tied into stator output.
 

jiju1943

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The 1976 rectifier never worked as someone hooked it up incorrectly, test it before you change it. They have the red tied into stator output.


In which picture? The red wire is hooked different in each. The first picture the red is hooked to the red, in the second picture it is hooked to the second wire. The red wire that was shot was badly corroded and almost into. Will it mess the rectifier up if the two yellow wires are crossed?

Both engines ran, so the rectifier had to be good, right?

I will let y'all know today how the wires are connected on each. I had planned to go to the lake today to check the engine out but will wait until someone tells me it is hooked up right. I appreciate y'all's patience and information.
 

jiju1943

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The 1976 rectifier never worked as someone hooked it up incorrectly, test it before you change it. They have the red tied into stator output.


I see the one you are talking about now. That was on the other engine that I now use for parts.

I went out there today and put the muffs on to see how the engine ran and was hoping we could go to the river. The motor never fired up, I checked and there was no spark to the plugs what so ever. I took loose all the wires I had hooked the tachometer and fuel gauge to, thinking maybe I had wired into the wrong thing. Well I must have done something wrong, I tried to fire it up again and all it would do is backfire and kick back like it had jumped time. Now I really don't know what to do, I am about at the point of giving up on this boat.

Just to let you know what I have done so far trying to get this boat on the water. We bought it in June, the motor hadn't been completely hooked up because the fellow just never got around to it. We had to buy two tires just to get it home. The motor on the boat was a 1976 85 hp Johnson Javelin, the man said the motor was good. I checked the compression and it was 100 psi on all cylinders. The motor ran really rough and would backfire through the exhaust, we took it to the river hoping it would blow all the junk out of it.

We went about 4 miles and went through 5 gallons of gas, I did everything I could think of and asked every question under the sun. I took the flywheel off checked the trigger and all under there was OK, put it back on and my grandson tightened the nut for me. Cranked it back up, still backfiring and running rough. Went back to the river to let it run in the water, wouldn't fire up at all. Woodruff key sheared in the flywheel. Replaced key. Never did get it to quit backfiring through exhaust, I took that engine off and put my other engine on which is a 1975 85 hp Johnson. After I got the engine on the boat I had to drop the foot and put a new impeller in. Put the foot back on and the motor and got the motor to running good, until I changed the rectifier and that is where I am right now.

There is way more to the story but this post has already gotten too long. I did find out why the Javelin was backfiring through the exhaust, the #1 and #3 coil wires were hooked up backwards, the fellow before me must have been in a rush or something.

My question now is, will the rectifier cause the engine to kick back, backfire and not crank?
 

jiju1943

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I found my answer, the rectifier will not keep an engine from firing up, as the rectifier is for charging the battery only. I did take my rectifier off and hooking the black lead of the ohm meter to the red wire then touching the yellow wires, I get a pretty high reading touching either yellow wire. When I reverse the ohm meter leads to the red wire and touch each yellow wire, I should not get a reading at all but I do get a smaller reading so the rectifier is faulty, I will replace it.

I took all the wires loose that I used to hook up the tachometer and fuel gauge, the engine did hit but not fire up, it acted like it was kicking back like it had jumped time. I will pull the flywheel tomorrow and see if this engine sheared the woodruff key. A side note, while trying to fire the engine up, the tach did work, if the rectifier was bad I thought the tach would not work. I will let you know what I find.

Side note, the rectifier was wired correctly on the 1975 but not on the 1976 engine.

Jim
 
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jiju1943

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interalian, thanks for the link. I did that as instructed yesterday, the instructions were, if there was any reading when reversing the leads of the multi-meter to the wires the unit was bad.

This is really weird, I just did the test again and the rectifier is reading that it is good. I place the black lead of the multi-meter on the red wire, the the red lead on a yellow wire, it reads 4.21 ohms, the other yellow wire reads .756. I reverse the leads on the multi-meter by placing the red lead of the multi-meter on the red wire and the black lead on either yellow and get no reading at all. This indicates that the rectifier is good.

I tried again, black lead to red wire, red lead to body of rectifier (ground) I get a reading, reverse and no reading. Same with yellow wires. Why did I get a reading that the rectifier was bad last night and today it reads good. The meter is new, well two months old. I have done this test 4 times this morning and it checks out perfect. Oh well, I will put it back on the motor and check to see if the battery is charging when I ever get the blame motor to run again.
 

interalian

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If your DMM has a diode test function it's an easier test than with plain resistance. Each diode junction should have a 700mV drop in one direction and read OL (overload) in the other.
 

jiju1943

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interalian, I appreciate that, I will check that out.

I gave the engine a try today and I have no fire to the plugs at all. I may have really goofed, I forgot the battery was still hooked up and after putting the rectifier back on, I was about to put the cover back on and my screwdriver hit the first red wire screw and ground. I just hope I didn't really foul anything up.
I have been all day reading about testing from the plugs all the way back to see why I have no fire. The way the motor was kicking back yesterday I almost feel it has sheared the key again, I guess that will be the first thing I check in the morning.

I appreciate your help, I will let you know what I find, if I do find anything.

Jim
 

jiju1943

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One more thing, is there a way to check the trigger coil input without one of the neon testers # S-80 or M-80 test lights? I can't even find one of the test lights online anywhere.
 

jdaghir

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CDI Electronics has a very good ignition troubleshooting guide, including how to test without the neon testers. You may however need a DVA adapter and possibly a load resistor. The guide is here: http://www.cdielectronics.com/support/

Also my understanding is that you need to be using a genuine factory Woodruff key. Keys from the hardware store are too weak and are prone to shearing.
 

jiju1943

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CDI Electronics has a very good ignition troubleshooting guide, including how to test without the neon testers. You may however need a DVA adapter and possibly a load resistor. The guide is here: http://www.cdielectronics.com/support/

Also my understanding is that you need to be using a genuine factory Woodruff key. Keys from the hardware store are too weak and are prone to shearing.


Jdaghir I appreciate the link, I will check it out. I do need to pick up the DVA adapter for my multi-meter.

I will also pick up a key from the parts shop when I pick up my rebuild kits for the carbs. I noticed that the bottom carb is gushing gas when I pump up the bulb now. I am about to give up on this boat, I have been working on it since the 2nd of June, except for building a wooden pamphlet rack. The summer is gone no fishing at all this year. I love fooling with things and working on the boat has been fun but now it has become tiring. I will say I have learned a lot though. Back in the 60s, I was a mechanic but boat motors and car motors are two different animals.

I did pull the flywheel off again and the key is still OK. The motor was running great until I hooked the tack and fuel gauge up, and installed another rectifier, now there is no spark at all. I plan to totally reverse all I did today, except for the rectifier. I can't put the old one back on because the red wire on it is gone. This rectifier I put on there now came off another 85 hp Johnson but was wired wrong. I did check the rectifier and the first time it checked out to be bad, I later decided to check it again and it checked out to be good. I will recheck the rectifier today. If I can't get the motor running this week, I will leave it alone and see if I can find another motor.

I know the motor is a good one because it was on our ole bass boat and ran like a champ.

Thanks again for all your help.

Jim
 

jdaghir

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Leave the rectifier disconnected while troubleshooting the lack of spark. It is for charging the battery only and is not necessary for ignition. In fact a failed rectifier can interfere with the cdi ignition (see the troubleshooting guide - disconnecting the rectifier is one of the first steps).
 

jdaghir

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Another note - if you do get a DVA adapter, the EMI noise emitted by the CDI ignition can cause some cheap, poorly shielded DMMs to have flaky readings or to lock up (my cheap Radio Shack DMM did). But a cheap, analog volt meter won't care about EMI noise. I picked one up from Lowe's for $15 dollars.
 

jiju1943

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Leave the rectifier disconnected while troubleshooting the lack of spark. It is for charging the battery only and is not necessary for ignition. In fact a failed rectifier can interfere with the cdi ignition (see the troubleshooting guide - disconnecting the rectifier is one of the first steps).

jdaghir, I did just that today, I took the two yellow wires of the rectifier lose, then I took the black with yellow stripe wire lose from the power pack and it fired up, so I know the ignition switch is shot. I will change out the switches tomorrow I hope.

In the meanwhile, I squeezed the gas bulb and the bottom carb flooded big time with gas. I am in the process of rebuilding the carbs right now. I made a post in the Johnson forum about the float adjustment. I hope someone answers quickly so I can get that part done. I hate to ask the question again here, the mods may not care too much for that so I will just wait.
 

jdaghir

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Glad you found the problem. Keep in mind that it is also possible that the switch is fine and that there is a short to ground somewhere in the wiring harness.
 

jiju1943

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Glad you found the problem. Keep in mind that it is also possible that the switch is fine and that there is a short to ground somewhere in the wiring harness.


I did find a wire that could have been grounded but I already have the switch off now so I am going to go ahead and replace it. I really appreciate your help.
 
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