Just rebuilt most of a 2 stroke jet boat. ( if you need / want any boat details, see: this thread )

First day the boat started fine, no problems, next day I tried again and the CDI fuse had blown ( see this this thread for details )

Yesterday, day two, I replace the fuse with the same rating. She fired up nice.

Today, day three, The new fuse is blown again.. I go thru, very carefully, and check for any visible wire, I found a few, wrapped wrap them in electrical tape and cleaned all the major terminals. I installed a new fuse and now I don't even get any power to the starter.

What should I check next?

*A similar wire diagram can be found here, on page 26 if it will help.



I opened up the CDI box and determined that the starter relay never powers the starter motor.

There is a brown wire that comes from the ignition, when the key is in the "on" position this brown wire gives 12.6v to the starter relay, when I try to start the engine, the brown wire only supplies ~8ish volts to the starter relay, there is also a black wire the goes to the starter relay...

Can some one let me know how / what to test next?


Would be safe to detach the signal wire and connect that terminal to the input terminal?

If no power goes to the starter would this confirm that the relay is bad?


I have confirmed that the starter relay and starter motor are working fine.

I believe I have narrowed down my possibilities to either the ignition itself or the safety laynard. As mentioned turning the key is to "on" is only putting out 8ish volt ( via the brown wire ), maybe the safety laynard is what is causing this drop?

The white wire comes from the safety laynard, connects to the ignition and then goes directly to the CDI Unit.

The black wire comes from the safety laynard, connects to the ignition and then goes to the CDI box ground.

How do I test my safety laynard to determine if it is the problem?

  • I'd keep the circuit intact for now. if you're only getting 8v at the relay than the coil either isn't closing or it is and something is causing draw on the system. If the wiring is the same as the posted diagram what does the output wire (red) to the starter have for voltage when cranking? if it's 8v than the relay is fine. and I'd suggest hooking an inline fuse up to your multimeter and measuring draw on the circuit. also measure voltage on the battery when cranking.
    – Ben
    May 26, 2016 at 21:51
  • actually on the posted diagram there are multiple red wires so you'd have to identify the wire to the starter. and by cranking i mean pushing the start button.
    – Ben
    May 26, 2016 at 21:58
  • @Ben, 4 wires connected to the starter relay: 1) Red Wire from battery, this ALWAYS has 12.6v. 2) Red Wire to Starter Motor, this NEVER gets power regardless of the state of ignition ( hence this threads subject ). 3) Brown Wire, this wire comes from the ignition, the starter relay receives 12.6v when the key is turned to on, it receives between 8-11v when the key is turned to start, otherwise 0v. 4) Black Wire, Ground I believe. Because voltage never leaves the relay, at this point i think that is the problem. Looking forward to any suggestions or ideas you might have for me!
    – Calvin
    May 31, 2016 at 12:40
  • it does sound like the relay is bad the voltage drop on the ignition wire is weird though. especially without that much load on the circuit.
    – Ben
    May 31, 2016 at 12:48
  • To test the safety lanyard ... bypass it. If it works bypassed, you have your answer. Jun 11, 2016 at 23:58

3 Answers 3


After looking at the circuit diagram, I will try and clarify what wires should go where. The ignition/starter circuit (key and Start button) should not be connected in any way to the Stop button and Lanyard.

Testing the Start circuit. With the key turned to the ON position, you should get ~12v on one side only of the start button (can't tell what colour wire from the diagram, but the short one that runs from the key switch, probably brown or red). When you press the Start button, you should then get 12v appearing on the brown wire that runs down to the starter relay. Disconnect the relay when trying this just to make sure all is ok with the wiring up to there.

Having said all that... You mention turning the key to Start position? It sounds like the circuit has been modified or is a different version to the one in the diagram. Do you have the Start button? There should not be any voltage going to the starter relay from the key when in the On position. It should only put 12v to the starter relay when turned to the Start position. Thinking of your wiring description, it is also possible the key switch is double pole, not single pole as in the circuit diagram, hence the black/white wires going to it. Is it possible to get a picture of the back of the panel with all the switch wiring showing?

Ok, next to test the kill circuit. It looks like it uses the standard method of cutting the CDI - a kill wire (white) runs from CDI to the Stop switch and in parallel to the Lanyard. The black wire is connected to ground/0V in the electrics box and when connected via either switch to the white wire, kills the CDI.

The Stop switch will be Normally Open. The Lanyard switch will be Normally Closed. When you attach the lanyard itself, it opens the switch allowing the engine to run. If you pull the lanyard out, it reverts to it's normally closed state and kill the CDI. So to test, put your meter into continuity mode and check that the Stop button is open circuit when not depressed and that the lanyard switch is also open circuit when the lanyard is attached.

If the Thermo switch is still in the circuit, you will want to check this in the same way as the Stop/Lanyard switches. It appears from the diagram to operate in the same way, Normally Open, when connected to ground will kill the CDI.

Of more concern is why the fuse is blowing. It appears the only power going through it is from the battery to the starter circuit and from the reg/rec unit to the battery once the engine is running. However, if as you say the lanyard and Stop are somehow connected to the ignition switch, as soon as you stop the engine, you will create a short and blow the fuse.

  • 1
    The problem was with the ignition, as mentioned it was putting out much less than 12v when turned to start ( ~9v ). I put in the new ignition and it is working perfect.. I used it several times this weekend and didnt blow any fuses either!
    – Calvin
    Jun 13, 2016 at 18:00

Use a voltmeter and trace the circuit for 12v from the battery to the starter, you will find where the voltage drops off.

Also trace it to and from the starter switch/button to the starter relay, check all circuits involved.

  • Hi Moab, Thanks for the assistance. I popped open the CDI box and found that when I turn the key, the starter relay is not sending power to the starter motor. How do I test to see if it a problem with the starter relay?
    – Calvin
    May 25, 2016 at 23:43
  • 1
    measure the voltage at the relay. I forget the pin numbers, the 'input' side should always have 12v. the 'signal' side should get 12v when the key is at the start position. If you get 12v to the 'signal' it should click and there should be 0 ohms between the 'input' and 'output' pins. If it does not click, the relay is bad. If you do not get 12v to the 'signal' side, the ign switch or wiring is bad.
    – rpmerf
    May 26, 2016 at 10:43
  • @rpmerf, please confirm: 'input'=battery connection, 'output'=starter connection, 'signal'=ignition. If so, input=12.6v (always), output=0 (always), signal= 0v when key is in the 'off' position, 12v when the key is in the 'on' position, and 8v when the key is in the start position. I will check the ohms between the input & output pins, do I have to disconnect the relay to test properly?
    – Calvin
    May 26, 2016 at 12:07
  • Connections are correct. output should be 0v when the signal is 0v. When the signal is 12v, the output should match the input. A relay is an electronic switch, when the signal gets voltage, it closes the switch between the input and output. You can test input and signal with the relay off, test the relay is working with the relay on and measure voltage at the starter. The ignition switch (or starter button) should put out 12v when turned to start and 0v otherwise.
    – rpmerf
    May 26, 2016 at 14:00
  • Ok I guess it has to be a problem somewhere before the starter relay then... Because, the 'signal' puts out 12v when the key is turned to 'on' and only 8v when turned to 'start', as you mentioned the signal shouldn't put out any voltage untill turned to 'start.' BUT, based on this, I would think that the relay would be powering the starter when the key was turned to on! This doesnt make any sense :(
    – Calvin
    May 26, 2016 at 14:51

If your problem is the lanyard, you should be able to disconnect the wires from it to test. It looks like it is in parrallel to the stop switch and should function the same electrically as the stop switch. Though you mention it going to the ignition switch or do you just mean the panel? The voltage to the key switch and start button should be 12 and the voltage out should be 12 as long as they are simple switch with 2 connections on either(one in, one out). --if that is the case you could simply jump a wire across the connections on each switch, in turn, to bypass the switch and confirm whether it is the problem.

Edit:. It the schematic linked is correct, it doesn't look like the black wire from the lanyard should connect directly to the ignition switch. Confirm whether your switch has only 2 connections like the one in the schematic. One should be power in and one signal out, which should connect 12v to the relay and to the start button.

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