This is embarrasing

[fireman57]

1984 50hp evinrude. Have had two of these engines before this one and thought I knew them inside and out. Had no spark at at all starting out. Replaced the power pack with a known good one and still no spark. Replaced stator with a known good one and got spark on the bottom cylinder. Swapped coils and still only spark on the bottom cylinder. Swapped power pack again with a known good one and still only spark on the bottom. Swapped coils and still only spark on the bottom. Wires from stator are good. Used CDI troubleshooting and unhooked rectifier and still only have spark on bottom cylinder. Stumped. Need some great ideas. I have a shop full of parts that I know are good and can't figure this one out. Thanks.

 

[Bosunsmate]

Try disconnecting the kill wire.
Also have you tested the timing base wires?

 

[AlTn]

1.grounding surface for upper coil isn't clean enough for good contact 2. pin for upper coil isn't connecting well into the female end within the rubber connector 3. ignition wire from coil to spark plug is faulty 4. have you checked the voltage output coming from the power pack to the coil?

 

[fireman57]

Already disconnected kill wire and no change. Grounding surface should be clean enough but will recheck. The new coils don't have the grounding wire but a "clip" that grounds it where the bolt goes in. Cleaned the pin connector but will try that again. I would think that after plugging three different coils in the pin connector would have been scraped enough to be clean but like I said I will recheck. Have not checked voltage from power pack. Went through CDI troubleshooting but some of it made no sense to me. What voltage should I be getting?

 

[Bosunsmate]

Did you check timing base?
Have you had flywheel off and checked for signs of shorts, that what caused it on mine, i had to re-epoxy mine

 

[fireman57]

Flywheel had to come off when I changed the stator. All wires from timing base looked fine. No cracks etc... I might try to ohm them out to see if I missed something.

 

[AlTn]

with the coil connected to the power pack,cdi gives ~ 180v dva for the pp wire to that coil....something I hadn't considered was given as well, esp. since you've tried multiple components with no change.....try another flywheel. I recall swapping an oem coil out with one that grounds through a clip. In that instance I ended up having to use several small washers to create a "spacer" so the mounting screw would hold that coil snuggly. Don't know if this applies in your case.

 

[TD_Maker]

Just a reminder that the coils must have a good ground. Also, try starting the motor at night (while its dark) with the hood off. Shorting coils and electrical components often leave a visible arc to help pinpoint the problem.

 

[fireman57]

Great suggestions AlTn and Td. I will try to get to that this weekend between rain showers. I should have thought about starting it at night as I have given that advice on several occasions. It's heck to get old. Thanks.

 

[sumocomputers]

I am really looking forward to what you find out. I am still trying to get up to speed on ignition/electrical systems on outboards, but the engineer in me finds it very baffling that only the bottom is getting spark, assuming the power pack and coils are in fact all good. I can't tell you how many times I had 2 of something I thought was "known good", right up until the third one proved me wrong.

The fact that the problem does not follow the coil swap, means it is either the spark plug wire on the top cylinder, or upstream from the coil. Just curious if you ever swamped the spark plug wires? Next thing upstream is the power pack, though it seems unlikely that both coils would have the same output good/bad.

As an amateur, I am curious what the voltages on the outputs of the power packs using your peak meter/DVA when you do that test. Mainly asking this so I can learn too. I just ordered my DVA & power pack plug extenders, to do some similar tests in the next week.

 

[fireman57]

Haven't had a chance to get back at it yet but the spark plug wires stay with the coils when they are swapped so that is out. Will try to get a meter on it this next week. No chance today with good weather and a wife that wants other things fixed.

 

[fireman57]

Finally got back to it. I have great fresh fuel as I went through the carbs again and with the plugs out cranking the engine there is plenty of fuel getting to both cylinders. I have a great bright blue spark now on both cylinders but it still won't hit. Flywheel key is good so don't know if/why the timing would change. Read Joe Reeves (my mentor) post on setting it without it running but the problem is my bulb in my timing light is out and I hate using a cheap one. Is there a way to check it with it not running except for Joe's method?

 

[tomhath]

A long shot, but are you sure the plug wires didn't get crossed?

 

[fireman57]

can't happen. top goes to the top bottom goes to bottom.

 

[AlTn]

any chance the wires coming from the power pack to the coils got reversed?

 

[fireman57]

Nope, double checked that too.

 

[gm280]

I read all the suggestions and there are all very good. But I don't know if you have checked the actual compression of the non-firing cylinder. If that cylinder is low enough, it will not fire regardless what fuel and spark you provide... Just a stupid suggestion... :noidea:

 

[fireman57]

Compression is 110 on both cylinders.

 

[fireman57]

Finally figured it out. Had a wire from the stator that was broken inside the insulation and if it moved ever so slightly it would cut out. On top of that a wire from the power pack to the buss bar had the same problem but it was to the opposite cylinder of the wire from the stator. Two rare problems that showed up at the same time on the same engine. Rewired everything and now all is fine.

 

[AlTn]

dang....no wonder you were scratching your head