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Old 14-05-2009, 17:56   #1
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Help! Outboard Diagnosis - Electrical

I have a 2004 8hp nissan outboard for my dinghy. It doesn't start at all. I bought an inline spark tester and that doesn't blink at all when I pull the starter. Using a multimeter, I found that when I pull the starter there is voltage going as far as the input to the CD unit but no further. Nothing into or out of the ignition unit.

My service manual gives the correct resistance levels for the electrical components. The ignition unit is supposed to be 0.3 Ohms +/- 15%. Mine was 0.7 Ohms. For the CD unit, there is an 8 x 8 table showing the appropriate resistance between any pair of the 8 terminals leading into the CD unit. I found almost all of these to be off rather than having the right resistance. I figured the CD unit was broken, so I ordered a new one, plus a new ignition unit just in case for a total of $200. I received the new ones today and performed the same measurements and obtained the same results. Still no connection between most pairs of the terminals on the CD unit according to my multimeter. And the new ignition unit reads about 0.8 ohms. I thought perhaps the multimeter was broken so I went over to Radio Shack and tested it on a couple of resistors. The multimeter seems to be working fine.

What am I doing wrong? I've never tried to repair this kind of stuff before so I'm probably making some mistake but I don't know what. I'd greatly appreciate any suggestions.
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Old 14-05-2009, 18:33   #2
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Is the safty lanyard clip hooked up? It's a safty device that holds the spring loaded kill switch in the up position and attaches to your wrist in the event you fall out of the boat. It kills the engine. I figure if the motor is new to you,then maybe your overlooking that.
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Old 14-05-2009, 18:42   #3
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Yes, the lanyard is hooked on. And I checked with the multimeter that the stop button works properly.
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Old 14-05-2009, 20:41   #4
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Time for a pro-fessional
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Old 15-05-2009, 03:06   #5
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Fuel, compression, spark...

I thought that basic diagnostic for small petrol engines was to check fuel, compression, spark.

I know it's basic but have you checked that there is fuel in the tank and that it is flowing through to the carburetor. There might even be a smell of petrol. Is there a filter and has it been changed recently?

You should be able to feel the compression as you pull the chord. Does it feel "normal"?

And spark. Can you remove the spark plug in some dark place and physically check for spark? Have a look at the condition of the spark plug at the same time. Time for a new one?

I may sound a little fuddy-duddy but my childhood memories are of electronics that didn't work. I suspect your spark tester. It almost certainly wasn't designed for small outboards.
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Old 15-05-2009, 03:21   #6
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This ,ay sound crazy but I replaced a coil on an engine a while back. No help. I then replaced about $1,000 worth of stuff including the main engine computer.

The coil I bought was faulty out of the box.

I suggest the simple stuff - remove the spark plug wire and if possible expose the terminal. Hold it near a ground and pull the string. No spark means that there is either no power to the primary - which you confirm there is or there is an open in the secondary.
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Old 15-05-2009, 06:04   #7
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Chances are you are using a digital meter....The specs are designed to be used with a analog meter.
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Old 15-05-2009, 06:09   #8
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Here's a link that may help.

Nissan Outboard Motor Repair
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Old 15-05-2009, 07:05   #9
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The first thing I would look at is the the "triangle of fire" Heat/air/fuel

If this is the first time you have tried to start it this year, and the engine ran last season, I would suspect the carburetor.....I rebuilt/cleaned about 10 last season due to "varnishing".

Are you using a new plug? It is a colossal waste of time to try to clean an old plug.
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Old 15-05-2009, 16:12   #10
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Well, I went to radio shack and bought an analog tester as Tohatsu Guru suggested. That helped in part. Now more of the pairs of terminals are On but certainly not all that are supposed to be. Maybe I have to use the exact same brand of tester as in the instructions--something about a Hioki 3030. I'm starting to think that these resistance tests are not all the helpful. The engine did run a few times at the start of the season. Then a couple of times it started and then died after a couple of minutes. Now it doesn't start at well. I cleaned and put in new parts into the carburetor this winter. I've also put in new spark plugs and new gasoline. I'm just not sure how to trace the problem anymore. I'm told that the inline spark tester is not a good idea so I'll try the other approach of just holding the wire near the engine. I was worried that I wouldn't be able to see the spark in the daylight.
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Old 15-05-2009, 16:53   #11
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Since they started fooling with gasoline - first MTBE then Ethanol - every outboard problem I've have is fuel related. Your symptoms sound like fuel too.

Are you using fuel from last fall? Or even fuel that the marina bought last fall and left in their tank all winter. If so, get rid of it - including the fuel in the fuel hose, bowl, etc. - Replace the fuel filter and spark plugs.

If this doesn't work, I'd get a mechanic. There's a real risk that you'll get so mad at the thing that you'll throw it over the side.

I now buy dinghy gas in 1 gallon jugs and mix the oil as I pour it into the dinghy tank - only a gallon at a time. I also give the jug a shot of one of the gasoline preservatives that say they work with ethanol fuels. After 60 days any unmixed gas still in a jug goes in the car.

Somedays I actually miss my old Seagull outboard with rope starter.

Carl
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Old 15-05-2009, 21:38   #12
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Joe, trying to make really tiny measurements (less than one ohm) with any kind of meter you get into problems. Problems like meter accuracy, impedance effects, resistance of the leads themselves and from any finger contact you have with them.

For instance, a "good" meter typically has a DC resistance range with an accuracy of 1/2% and the minimum ohms scale may be 200 ohms. (199.9 on the display) That means there is an error of 1 ohm, and you're trying to measure less than half of that. Ain't gonna happen! And that can be a $200 meter.

Even if you move up to a meter with a high precision resistance scale, most meters have a "float" of 2-3 on the least significant (rightmost) digit. So a reading of 0.5 can actually be anything from 0.2 to 0.8 and still be "correct" for the meter.

In order to accurately test for a 0.5 ohm resistance, you'd probably need a meter with a 20 ohm scale (i.e. 19.99 ohms), and it would also have to be a calibrated meter--again more expensive.

So while a consumer grade meter may tell you that the circuit is neither zero ohms nor twenty ohms...you can't really rely on it for telling 0.3 ohms apart from 0.8 ohms. Sometimes they will, often they just can't. It is very much like a GPS: You need to know that they are never, ever, going to be dead on to the final inch.
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Old 17-05-2009, 20:55   #13
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I swapped the CDI unit and the ignition coil for new ones. I still don't see a spark in my spark tester and my digital multimeter shows zero volts coming out of the CDI unit into the ignition coil. I don't have a peak voltage tester but shouldn't I be able to see at least something coming out of the CDI unit? I did see voltage going into the CDI unit when i pull the handle. And the safety lanyward button seems to be working normally. I've already tried disconnecting it. What else could the problem be? Or maybe I'm measuring something wrong?
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Old 17-05-2009, 21:44   #14
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Do you have a schematic? These days, anything including your toaster could be interfaced into the cdi and necessary for it to function. Is there a neutral start safety switch on the transmission? Is that in neutral, and confirmed functioning?

And, are you sure your meter is configured properly and working properly? No fuse blown in it?
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