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What does a failed power pack test look like?

G

GLE3

Member
Hi all, I have a 72 100 HP Johnson that has an intermittent spark issue. I'm trying to test the power pack with my multimeter (cheapy from Menards) and a DVA adapter (ESI-640 Dva Peak Voltage Adapter). From what I read I am supposed to be at about 200V cranking at the coil wire. So far the measurements seem sporatic, flashing up and down as I crank. Should I get a consistent voltage even if the pack is bad or would I expect it to fluctuate?
 
Step # 1 on those is to remove the flywheel.--------Clean distributer cap and rotor.-----------Check anti-reversing spring.--------Perhaps replace the wee rubber boots on plug wires at the cap.-------------------Note the wires are screwed into the cap.
 
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(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
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(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
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