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Old 02 November 2014, 08:47   #1
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No spark....help!!

I have a yamaha v4 115hp that has no spark on any of the plugs!

Tried switching coils around, cleaned the plugs.

There's fuel getting to the cylinders, it turns over but won't fire!

Any got any ideas??

Thinking it might be the coils but not 100% sure

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Old 02 November 2014, 09:06   #2
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Kill cord circuit ok?
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Old 02 November 2014, 09:40   #3
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Yep, checked all the fuses too.

Had one plug sparking briefly then stopped
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Old 02 November 2014, 10:52   #4
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Very rare problem on a Yamaha.

1) Find out if it is the control box or engine. Disconnect the control box and Hotwire the engine by touching the bullet on the brown wire on the start solenoid to the incoming positive cable from the battery. This will spin the engine while you check for spark. If it sparks it is likely the kill switch, start in gear prevention switch, ignition switch or the loom itself.

2) if it does not spark on all 4 after doing the above, it would be unusual but likely to be the CDI.

3) if it fails to spark on a single lead, I would change out the coil.

Let me know how you get on.
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Old 02 November 2014, 11:02   #5
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Thinking again. Don't worry about the start in gear prevention switch. It cuts the brown wire so your engine would not turn if there was something up with it. My money would be on a broken loom wire or the other control box switches.
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Old 02 November 2014, 11:41   #6
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Didn't think of the loom, will check it over all see what happens
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Old 02 November 2014, 12:36   #7
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I would recommend the repair manual for specs, and tests, along with a volt ohm meter. There should be a barrage of tests to run.
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Old 02 November 2014, 17:04   #8
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Check the continuity of all the wiring loom with a multimeter. Saves a lot of time down the line. Outboard manufacturers should use tinned wire. If it's oxidised an turned black that could be the source of your problem. Had similar issue with my Tohatsu, but it was the trim not the ignition.
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Old 03 November 2014, 10:36   #9
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Update-

Been fiddling with the wires and by some miracle got the plugs sparking!!

However, I try turn it over and it tries to start but doesn't quiet have the power. It will fire but only off the starter motor. (300-400rpm) it then backfires!?

Also noticed an arrow for my oil on my gauges. May have always been there just not noticed. The engine has oil and have tested the pump which works fine.

Don't think it's linked but still wonder what it means?

Ordered a fresh set of spark plugs and will carry on tommorow.


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Old 03 November 2014, 14:50   #10
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Did you by any chance when checking the coils, remove the black and white wire from the coil itself or the CDI box. The slow turn over and backfire is classic out of sequence firing. If you replaced the black and white wires incorrectly, this word give exactly that.

Also those engines require a battery (from memory) of over 100AH or funny things happen with the tacho like the oil warnings going funny.

If you fiddled and suddenly everything worked, you must have a loose or bad connection and it will have to be found and fixed or you are RNLI fodder.
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