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1979 Evinrude PwrPack Verification

S

stromzilla

Contributing Member
"I'm trying to verify the

"I'm trying to verify the diode in both Pwr-Pks. Manual says it should read some ohms in 1 direction and Infinity ohms in the other. I get the Infinity on both packs in 1 direction, but when I check the other direction I get about 1500 ohms when I first touch the terminal then it goes to Infinity too. It sounds like the diode is bad because that's not very much current coming from the ohm-meter. It's doing this on both Pwr-Pks. Does anyone have any thoughts on this scenario?"
 
1 st question did you loose sp

1 st question did you loose spark on either side
2 nd are you getting power to the packs from magneto
 
"The issue I'm having is a

"The issue I'm having is a rough-running engine. It stumbles from idle up through about 3500 rpm while under a load. To answer your question...I may be losing spark momentarily. The Evinrude manual talks about the Pwr-Pks causing confusion if the diode is not functioning properly (fully open or shorted) which in turn could cause a rough-running (so the manual says) engine. Carbs are good. Plugs are clean. And also, at full throttle it runs real well (so well in fact the engine is over-reving) so I suspect the magneto is getting pwr to the Pwr-Pk. I'm just trying to eliminate some possibilities before I start replacing things. Before I get too far off-track I'd really like to understand the diode in the Pwr-Pk and what the proper procedure is for verifying whether it's good or bad."
 
Could someone with a good or n

Could someone with a good or new Pwr-Pack for a 1979 thru 1984 Evinrude V4 check the 4-way connector terminals at the white and Bk/Y circuits? An ohm-meter set at 20k is needed. Touch the 2 terminals and take a reading then reverse the leads and take another reading. It should read Infinity in 1 direction and some amount of ohms in the other direction. I'm beginning to think the diode in both P-paks are bad. I get Infinity in 1 direction then about 1800 ohms in the other direction momentarily then going to Infinity. This would indicate the diode is open in both directions which is not good.
 
"i have looked at my clymer ma

"i have looked at my clymer manual i see no referance to a diode in the packs,and reading your post about poor idle leads me to belive
that something else is wrong,usually when a pack goes bad it stops working on one or two cyls. have you done a compression test lately,a good carb cleaning.new plugs etc fuel filter.
possable leak down test,you say it stumbles up to 3500 rpm /thats about when the high speed jets come in to play.
have you done a power pack output test"
 
Compression is 120/120/125/130

Compression is 120/120/125/130. Plugs are exceptionally clean. Carbs are exceptionally clean...first thing I went through. And I installed an inline fuel filter. On page 4-9 of my OMC Evinrude manual it talks about "Rough Running Engine" and specifically references a faulty isolation diode in the power packs and how to check for that diode as being good or bad which I've already described. On page 4-3 there is a diagram that shows 4 diodes in a Pwr Pk so I'm fairly confident the Pwr Pk contains a diode. The paragraph is written as follows: A rough running engine may be due to interaction of the power packs because of faulty isolation diode in power packs. And then it goes on to describe the trouble-shooting process for this issue.
 
ohm meter on high connected to

ohm meter on high connected to the d terminals on each connector note the reading.
reverse the test leads one reading will be high
other will be low /. if both are high diode is open.if both are low its shorted.
if they are both high /low its junk
based on your first post it looks good.
 
"I disagree. Please read my f

"I disagree. Please read my first post again. I get a high reading in one direction and a low reading in the other direction initially (as in less than a second), then it goes high. Diodes don't normally operate that way. To me both directions are high. That's why I'm looking for someone to check a power pack that's known to be good to see if it exhibits what I'm seeing on mine or what I think it should be which is a steady high and a steady low in the other direction."
 
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