Multiple sparks or mistimed sparks on 68 Evinrude 100hp

autoarcheologist

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Apr 23, 2014
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I'm trying to get our 68 100hp Evinrude running again. We used it last summer, then one day it died at the dock and wouldn't start. I diagnosed the problem as a bad ignition module (which was relatively new) so I sent it back to CDI and they replaced it. The wiring harness, plugs, coil and rectifier are also all new, as is the battery. The carbs were tuned last year and winterized last fall.

This summer I also replaced the sensor rotor with the "Phase 2" rotor with smaller lobes per the CDI instructions.

It seems like the engine will fire once, but too early, then shut down. I assume it's kicking the engine the wrong direction and the anti-reverse spring is shutting it off.

If I test the ignition alone I get a nice spark. But the odd part is that the ignition fires both when I tough the two sensor wires together, and again when I pull them apart. I thought it should only fire when grounded together.

I tested the ignition system by rotating the crankshaft to each cylinders position, and I only get a spark from the correct cylinder. All 4 cylinders spark.

If I crank the engine with the plugs out but connected and grounded, I see multiple sparks and it's hard to tell if they are firing in the correct order.

Is it possible to get a bad module that fires too many times?

Should I go back to the rotor with larger lobes, so even if it is firing too many times it won't matter as much?

I also tried disconnecting the anti-reverse circuit, and got one loud backfire when I tried to start it, so that also sounds like a spark at the wrong time.

Any thoughts? I'd love to get this running again and use it a few times before winter hits.

Thanks!
Ian
 

autoarcheologist

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I forgot, I also tested the magnetic sensor and it reads 5.2 ohms, within specs. I'm not sure how to test it while the engine is spinning, but I did close up the gap to 0.011" from the 0.020" it was at. I can move it back, but it didn't seem to make a difference either way.
 

autoarcheologist

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Just a quick update, I went back to the original rotor and it seemed to work better, but I still never got it running. I think I have a carb issue now, and will post a new thread about that.
 

racerone

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Where did you find those values for the sensor gap?--------That seems way too close going by memory on those ignition systems.
 

racerone

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Does spark on the plug leads jump a gap of 3/8" or more, yes or no ?-----I did recall the 0.028"' from memory , but never a gap of 0.011"
 

autoarcheologist

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I'm still fighting this issue, here's an update:

Thank you to everybody who's helped to try and get this stupid motor running. It was a blast when it ran, albeit briefly, so I'm hoping to have it running again.

A little background, we bought the boat in 2014 and after running very briefly I noticed the insulation on the wiring was all flaking off and read about the problems they had with the wiring supplier in 1968. The CD module stopped working so I bought a new module, wiring harness and rectifier from CDI and installed them. The boat ran well for a few trips, then near the end of the summer it started then died on the dock and wouldn't restart.

Testing revealed the CD module wouldn't spark, so I sent it back under warranty.

After getting it back the most I can get out of it now is a spark when I tap the sensor wires together.

Since I started this thread I swapped in the new "Phase 2" timing rotor with smaller lobes, and a new magnetic sensor and wiring. So at this point the CD module, wiring harness, rectifier, rotor, neutral safety switch and magnetic sensor are all new. Plugs are new as well.

Here are the tests I have run this week:

I have gone through all the troubleshooting steps outlined in the CDI troubleshooting guide but I am not getting a spark through the sparkplug while cranking.

I have checked for battery voltage at the red/purple wire going to the CD module and read 12.6V. While cranking it stays just above 10V.

Joe I even built one of the diode wires like you recommend, but I measured the voltage at both sides of the starter solenoid and the voltage drops to about 10V in both cases. Should I still install the diode jumper?

If I disconnect one of the black/white wires coming from the sensor to the CD module I will get a spark. Not when tapping them together, but when I pull them apart to break the ground.

I can get this spark both with an ignition wire straight from the coil, as well as when I set the rotor and distributor to point to cylinder #2 and use cylinder #2 plugs and wire.

I have tried cranking with the original phase 1 rotor with wide lobes with also currently with the smaller phase 2 rotor.

If I crank the engine with the sensor connected but the coil wire going straight to a spark tester, it will only spark when I let go of the key. The sensor doesn't seem to be triggering anything.

I have tried setting the sensor gap to 0.028, 0.020, even as small as 0.018 with no spark. If I insert a feeler gauge between the sensor and rotor it will spark, but if I pass a feeler gauge in front of the sensor by itself it doesn't.

All signs are pointing to the sensor not working, or the CD module not accepting the signal from the sensor. Again the sensor is brand new and just installed this past week. I was having the same issue with the previous original sensor which is why I replaced it. Both sensors measure 5.0-5.1 ohms, within specs.

I removed the clipper circuit and the vacuum switch, the only safety switch is the safety switch for the starter. The anti-reverse spring is still installed, but there is no wire on the new harness for it so it's not connected to the green/black wire on the module.

My next step is to build a DVA adaptor and measure the voltage coming off the CD module, but since it will spark when I disconnect the sensor wires I believe it's working.

I'm also thinking of trying a 0.010" gap and see what happens. I will also try hooking up our old sensor again and pass something large and metal in front of it like a screwdriver to see if it sends a signal.

I can also try removing the anti-reverse spring completely to rule it out.

Any thoughts? I'm at my wits end trying to get this engine to spark properly so we can use it this summer!

Thank you again everybody!
Ian Lomax
Portland, Oregon
 

racerone

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Post a few pictures of the black rotor.----Is there a 6 digit number on the distributor cap ?
 

autoarcheologist

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I haven't changed the rotor or distributor, and I have tested them and they seem to be passing a spark. Why do you suspect them?
 

autoarcheologist

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Another update. I picked up a DVA meter and measure the voltage at the blue wire coming from the powerpack to the coil. I get up to 300V so I believe the powerpack is good.

However when I measure the DVA voltage across the trigger / sensor I get nothing. So it appears that the sensor is not sending any signal to the powerpack.

I found a DVA chart on the CDI website, but it doesn't list the 68 engine. http://www.cdielectronics.com/wp-content/uploads/2013/03/CDI-Electronics-DVA-Charts.pdf

I'm assuming based on the chart I should see at least 0.5V from the sensor. I'm going to try removing the anti-reverse spring and playing with the sensor gap to see if I can get it to work.
 

autoarcheologist

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Another update, still no luck.

I removed the anti-reverse spring completely.

I double checked the resistance of the sensors, still 4.8-4.9 OHM. I checked each wire to ground and found no issues.

I added in the extra wire with diode running from the starter terminal to the 12V going to the powerpack.

If I line up the distributor to cylinder #1 and tap the wires together I get a nice hot spark that jumps a 1/2" gap.

But when I crank I still get nothing. I tried it with a 0.028" gap, 0.0.20" gap and 0.015" gap. I don't get any kind kind of voltage reading with a DVA adaptor connected between to the two sensor wires. And I don't get any sparks when cranking.

I measure about 10V at the 12V powerpack wire when cranking.

I've done every test in the manual and it still doesn't work. I even tried a spare flywheel thinking the flywheel magnets might be going bad, still no luck.

I'm not even sure I can convert it to points, as I don't see the bumps on the crankshaft like the 85hp engine has to open the points.

Any other suggestions or longshots? I've run out of ideas, and I'm afraid the next step is selling this off as a project and getting out of boats for a while.
 

JRegier

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Aug 17, 2013
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Did you ever have the flywheel come loose? I've got a '69 115 where my flywheel nut wasn't torqued down enough and the flywheel key sheared; I swapped the key and put it all back together but only had problems. Turns out there's a small plastic nub on the distributor rotor that turns it with the flywheel and mine had worn off and caused my problem. Just throwing any idea out there.
 
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autoarcheologist

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Apr 23, 2014
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No, the flywheel key is still good and that distributor rotor nub is still there. But that's a great suggestion, and I can double check that the rotor is seated correctly next time I'm out at the boat.
 

billybaru13

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Aug 27, 2014
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Very curious where you left off on this project. I am about to convert my 68 100hp to a MSD ignition. the only thing confusing me is the rotor. I dont understand the difference in timing between the phase 1 and phase 2 rotors. IT seems that they are mirror images of each other. Phase 1 has a long section of metal, and a small air gap, and phast two has a short section of metal and a long air gap. Im not sure what the MSD ignition wants to see. My gut says phase 2 .. but not sure...
 

autoarcheologist

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Hey Billy, I sent the module back to CDI and they said it was bad. Two bad modules so far, not a good track record.

I'm now having an issue where I crank it and it doesn't fire until I let off the key. Then is sometimes get one big bang. I assume that is from the module being grounded out.

I tested and saw some Sparks when I just cranked it with the coil wire close to a ground. And also when I pulled a plug and grounded it.

I'm currently using a phase 1 rotor because I couldn't get it to work with the phase 2 rotor. It ran briefly a few years ago with a new module and the phase 1 rotor. But ever since that module died I haven't been able to get it to run.

I would love to convert to MSD but I don't think the MSD box will work with our magnetic sensor. You should try hooking it up and testing it to see if it will.

I wanted to convert to points and go with an MSD but the 100 hp engine doesn't have the bump on the crankshaft to open points. Maybe you could rig up points to open with the lobes of the sensor? I'm not sure but I'm happy to help. I would start a new thread to get other input.
 
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