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1972 125 HP Model 125283 no start/ clipper module question

B

Brian J

Member
Just bought boat and had it out on water. Ran good for 10 minutes then had only half throttle before in would just bogg down. Fix this problem with a carb clean and fuel pump. Also had to put on a new starter. Replaced the water impeller as well.

Had it back out on water WOT and it ran good for ten minutes then just shut off. (just like someone turned the key off). Started trouble shooting--- no spark.

Compression is 110 on three and 95 on the other. Using manual to trouble shoot but can't get it to spark. I have the CDI pulse pack 113-8362. Everything checks out except the coil. The pulse pack checked out OK. I could not get the coil to spark. The coil had a high resistance 125 OHMS so I think it is bad.

Removed the coil for inspection and it had a crack on the bottom. Ordered a new coil.

I also noticed during my inspection that the clipper circuit is still installed. I have a copy of the CDI installation and troubleshooting guide off the internet. It states to remove any clipper modules. On my parts list item #88 states Clipper circuit assy. It is still installed and hooked up to the terminal board. Should this be removed?

Any help on the clipper or electrical trouble shooting would be helpful.

Thanks
 
Yes, remove the clipper circuit. It was originally designed to prevent possible power surges from from the charging system, but it created more problems than it solved.

(Voltage Drop To Battery Capacitance Discharge)
( Pulsepack When Electric Starter Is Engaged)
(J. Reeves)

On the older Battery Capacitance Discharge ignition systems (1968-1972), the electric starter reaches a point, even with a top notch battery, whereas the starter will draw excess voltage/current/whatever which results in a voltage drop to the pulsepack. The cure is to purchase a diode which is capable of handling 12 volts and installing it between the starter terminal of the starter solenoid (NOT the battery cable terminal) and the wiring terminal that supplies voltage to the pulsepack.

The diode must be installed so that the current flows from the starter terminal of the solenoid to the pulsepack... NOT vice versa. When that diode is installed in this manner, when the key is turned to the start position, the voltage that is applied to the starter is also applied directly to the pulsepack via the diode effectively eliminating the voltage drop and energizing the pulsepack with the required voltage needed for its proper operation.

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

********************
(Battery Capacitance Dischage Powerpack Test)
Various OMC Engines - 1968 to 1972)
(J. Reeves)

Purchase a small 12v bulb at your local automotive parts store (the 12v bulb is to look like a flashlight bulb, not a headlight bulb). Solder two wires to that bulb, one to the side of the bulb (ground), and the other to the positive point. You might use a bulb of a somewhat lower voltage to obtain a brighter glow... just a suggestion.

Remove the spark plugs. With the key in the on position, make sure that you have 12v going to the pack at the terminal block (purple wire). Now, connect the ground wire from the bulb to any powerhead ground. Connect the wire from the positive point of that bulb to the powerpack wire that is connected to the coil wire on the terminal board (blue wire).

Crank the engine and observe that bulb closely (CLOSELY!). If that bulb glows even the slightest bit, the powerpack is okay. It may be a very dim glow... just so it glows! If it doesn't glow, the pack has failed.

Keep in mind, that type powerpack (Battery Capacitance Discharge) demands a top notch battery of at least 70 amp hours. Any less will, in time, cause powerpack failure.

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 for the information, but I have some more questions. I did do that test with the light bulb and it did shine. Like I said in my post I believe the pack is good. The coil had no output and it also had a crack on the bottom. When the coil comes in I hope it solves my problem.

Looking at my manual and the engine I found the clipper circuit installed. I also found #73 Diode and lead assy and # 33 rectifier installed near the terminal board. I thought the diode and the rectifier was identified to the charging circuit. In my repair manual chapter 7 it details rectifier diodes for the charging circuit. It is confusing because I have both a rectifier and a diode installed that I can see. Chapter 4 details the ignition system and says nothing about diodes or rectifiers. Anyway I have no problem with the charging system.

I did take the flywheel off and everything looked fine. Nothing was loose or burned.

Ok. You say remove the clipper and so does the instructions for the pulse pack. I will do this. Now the diode you are talking about installing. Do you have one? If I understand you correctly I would install one end on the solenoid terminal that has the red large wire going to the starter and the other end to the wiring terminal that supplies power to the pack (is this the purple wire that goes to the terminal board for ignition power??). There are two other wires attached to terminal #9. Does this matter?

Hope I explained this correctly as I am new to this boat motor but I can usually tackle mechanical issues.
 
I don't have the diode, try radio shack. Yes, from red wire on solenoid terminal that leads to electric starter, NOT the terminal that has the battery cable attached to it. Other end of diode attached to purple wire that leads to pulsepack.

The rectifier is strictly for the battery charging system.... metal, 3 wires, 1 red, 2 yellow, triangular base.

The other diodes you're speaking of.... I suspect they might be shift diodes. They would be in a dark colored epoxy non encased clump.

I don't have the manual or wiring diagram in front of me so I'm in the dark pertaining to numbers 73, 33, 9, whatever.
 
Thanks for the info. Do you know how I can tell on the diode which way is the flow? I understand that a diode is one way. I need to make sure the flow goes to the solenoid then to the pulse pack. Will the diode have some kind of flow arrows in it? Do not want to hook it up backwards. Thanks for helping me out. I am on my way to radio shack to buy the diode. I except my coil to be tomorrow. I'll let you know how it goes.
 
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Some things are easy to overlook. My post included the statement "The diode must be installed so that the current flows from the starter terminal of the solenoid to the pulsepack... NOT vice versa." (No Biggie)

Use an ohm meter to find out which way the current flows in a diode. You'll get a reading in one direction and none in the other direction.

When you get a reading.... the diode lead that the RED meter wire is touching is the end that connects to the starter cable.
 
Make sure that your pack is well grounded. Clean all ground contact points that the pack connects to and make sure they are tight. Also the pack mounting plate where the terminal board is also mounted, check the ground from that to the engine block for a clean, tight connection. This was also a concern that a loose or dirty ground could cause surges in the operation of the pack that would quickly shorten its life. Good luck.
 
It is my understanding that CDI engineered their pulse packs to not need the external clipper circuit. But what do I know about what went on in their labs?
 
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