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1972 125 Evinrude electrical issue?

B

Brian J

Member
Had this boat for 3 weeks now and I have the same problem.

The boat will go WOT at first about 5 to 10 minutes then slowly lose power until your trolling.

Did all the checks, compression is good. Pulse pack checks out. Wiring seems right.

At first I thought it was a fuel issue and I rebuilt carbs and replaced the fuel pump (was leaking). Changed plugs from the NGK surface gap to the Champion JC4. Ran better but the problem is still there.

Replaced a starter (went bad) previous owner did not know how to use the automatic chock and wore the starter out.

On the 5th test drive motor died like someone turned off the key. Trouble shot that to*a bad coil. Previous owner tightened*the coil down to hard and*cracked it.


Motor fired right up after I put in a new coil. Removed the clipper circuit and motor backfired and would not start.*Put clipper in and started right up but motor would not shut off. Trouble shot that to a open blocking diode on the remote throttle. Related maybe??


Next test drive ran alot better. Had it*up to 5500 RPM's and 32 MPH. Held it there for quite awhile. (10 minutes)*Did several hole shots. Seemed fine then it started to miss again at high speed and slowly gave it up until I was at trolling speed.


I am thinking pulse pack now. I hate to do it because it checks out but*everyone is saying they usually solves the problem. Not always though. The previous owner said he had replaced it but I don't know how*long ago. I have the CDI 113-8362 pulse pack.


I was thinking maybe it could be the temp*sensor. I was thinking on pulling the two wires off the terminal board and trying that since it happens when it gets warm. It is not overheating. I can touch the flywheel with my hand for 6 or 7 seconds. In addition I replaced the impeller and lower unit oil with type C.

Also had the flywheel off and eveything looks good. I did find the ignition coil wire was stripped of its screw in and I replaced the wire with a new one I received with my new coil. It did run better but same problem.


Does anyone have any ideas.* This motor runs great for 10 minutes then slowly gives it up. It doesn't die but runs real rough. Tomorrow if I take it out it will probably run great for 10 minutes and do the same.


Temp issue, pulse pack issue?* Why couldn't I keep the clipper off.


*
 
Champion JC4?? S/Plugs should be either Champion L77JC4 or QL77JC4 plugs, gapped at .030 .

Overheating?? Does the warning horn work? Test by (engine not running) key in RUN position, ground out TAN wire you see protruding from the cylinder head. THe horn should sound off. Does it? If the engine starts to overheat, that horn will sound off before the engine gets hot enough to do any damage, hence the terminology "warning".

Clipper circuit... Removing the clipper circuit should not interfere with the ignition UNLESS you have something at the terminal strip wired wrong, a metal jumper missing, something of that sort. Remove the clipper circuit, now find the purple wire that has 12 volts applied to it when the key is in the RUN position and no voltage when the key is OFF. Connect that purple wire to the purple wire leading to the pulsepack.

When that engine loses power.... does the fuel primer bulb have a tendency to be drawn flat?
 
The horn never sounded, but I am thinking that since I lose power after it has been running ir could be the engine thinks it is overheating. I will short out the horn to see if it works. I am using the QL77JC4 plugs gapped at .020. That is what I have read in numerous forums. I don't think that is the problem because the motor runs good for 10 minutes. If the gap was wrong it would runs rough from the first second, right?

All the wiring looks right. I chased them all through a wiring diagram. The purple wire from the pulse pack is attached to terminal 9 where the ignition is. Again I don't think this is the problem because it runs so good for 10 minuites.

The fuel bulb is nice and hard and I have tried to pump it and even opened the gas cap (built in). DOesn't seem to matter!


The clipper makes me real nervous. When I removed it the engine wouldnot even run and back fired bad. That is what I think shorted out the blocking diode in the throttle remote so the motor won't shut off. It has never backfired except when I removed the clipper. I have the CDI instructions for the pulse pack and the wiring seems to be fine.

I think something is going south when the motor heat up after running awhile. Could it be the circuit in the pulse pack? or some other electrical issue? I don't think it is fuel because it runs well for 10 minutes and the carbs and fuel pump are good.
 
Did some research. There are two wires coming out of the head. The manual tells me it is the thermostat housing containing pressure relief valve, vernatherm control element and thermostat valve and spring. It has two wires coming out. One is purple/yellow and the other purple.

There is also a wire coming from cylinder #3 which is brown. This is the temp switch. According to the book this is attached to the warning horn.The book tells me to ground out the knife switch with the key on to short the horn out. I do not see a knife switch. Could it be under a long piece of rubber? I will check. Can I use a 12V test light to ground out this switch or is there some other way. I have not done this before so any help would be appreciated. Thanks...
 
You are confused! The ignition points on various models set at .020..... there is not one Evinrude/Johnson model that has the spark plugs set to .020. The spark plugs must be set to .030 .

The two wires you speak of... purple and purple/yellow are leading out of the top portion of the crankcase, not a head. They create more problems and are to be eliminated as per a OMC service bulletin as follows.

(Temperature Actuated Choke Solenoid Conversion)
(J. Reeves)

Various OMC engines that were manufactured in the later 1960s thru the early 1970s, for example the 1969 55hp Evinrude/Johnson incorporated a dual stage choke solenoid...... easy to identify as they have two wires leading to the solenoid, one purple/white, one purple/yellow.

The purple/yellow is attached at the engine wiring terminal strip to another purple/yellow wire that led to a heat sensor. The initial stage, with the key ON, (purple/yellow), when cold, would keep the choke pulled in half way until the engine warmed up, at which time it would release and open the choke butterfly.

The second stage (purple/white) is attached to another purple/white wire at the engine terminal strip which leads to the choke switch. When the switch was engaged, the choke closed etc.

The problem with this setup is that as the engine got older, the thermostat acted up, water pump became weak, whatever, the heat sensor failed to operate properly and the choke would not release from that half closed position.

This would cause the engine to run in a rich fuel mixture condition (flooding, loading up).

The cure to this problem, via a service bulletin from OMC was to remove the solenoid purple/yellow wire from its original location and connect both of the solenoid wires (purple/yellow & purple/white) to the engine wiring harness purple/white wire at the engine terminal strip.

The above change would allow both solenoid wires to be energized when the choke switch is engaged, pulling the choke butterfly in firmly..... and only when the choke switch is engaged.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
 
Thanks Joe Reeves. I checked the gap on the plugs and they were at .030. Don't know why I said .020.

Checked the wiring on the choke solenoid and it hasn't been changed. It is still as detailed on the wiring diagram. I did change per your instructions. This change makes total sense because the way the motor is behaving it is possible the choke could be stuck partially closed. Didn't even think of that problem. I will also remove the front plum so I can see the carbs if this doesn't work.
I hope this fixes the problem. I am going down to dunk the boat either this afternoon or tomorrow. I will let you know what happens.

Thanks again Joe
 
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