Make a guess

[jeff acton]

I bought a 1987 Yamaha V4 115 that had been stored for several years. Clean motor with great compression. Had carb kits installed by professional. Now l have another issue. The motor runs great and starts everytime all day long. Next day will not spark. I been to the 3 authorized shops in town ( on is a certified Yamaha dealer) and they don't know. It will run fine for them and when I get it home it has no fire. Several times the shops agree that it has no spark and in an hour it will fire right up for them. All the wireing has been tested. All the obvious has been done. All connections are good. We are all ready to start swapping parts. I really have no choice. Which part do I buy first? CDI unit, stator, ?????? how many parts can control the spark? Any thoughts please. The machanics are all scratching their heads. And my summer is passing. Please know that I have pretty good machical sense and I have gone over the motor numerous times. Nothing is loose or broken. An internal part is failing. Thanks Jeff

 

[robert graham]

Re: Make a guess

Maybe a bad wire or connection in the ignition switch or neutral switch, inside the 703 remote control unit?....or a bad connection in that main harness connection on front of motor?...but just guesses. Good Luck!

 

[jeff acton]

Re: Make a guess

Thanks Robert, as I have already stated, all wires and connections have been tested. Kill switch has been disconnected for trial.

 

[robert graham]

Re: Make a guess

Sounds like an electrical ghost...difficult to troubleshoot, and throwing parts at it can get expensive...Hopefully some of the electronics guru's on here will be able to offer up some ideas for you! Good Luck!

 

[coastalrichard]

Re: Make a guess

Jeff, I know you stated all connections were good but, are you sure the battery connections are really shiny and tight?

 

[Jlawsen]

Re: Make a guess

Three shops and no one can find the problem? Typically this problem is either in the neutral safety switch in the control or the saftey lanyard switch. If it's heat related any shop worth their salt would have used a hair dryer to induce the problem while it was running.

 

[99yam40]

Re: Make a guess

Things will have to be tested while problem is there.
Simple enough to disconnect kill wire from CDI to see if that helps, if not then test charge and pulsar coils to see if they have in spec reading on voltage and then ohms to CDI and out puts from CDI.

How did you test for spark when it would not fire up?

 

[jeff acton]

Re: Make a guess

Will check the battery terminals for the fifth time but starter and all else works fine just no spark to plugs at times. Thanks, Jeff

 

[jeff acton]

Re: Make a guess

The neutral safety switch will not allow the starter to turn, and does not control spark to the plugs. As stated in my original post the lanyard kill switch has been bypassed while testing. Heating is not the problem since the conditions in the garage are always the same. All shops cannot make the motor quit while it is running. Thanks, Jeff

 

[99yam40]

Re: Make a guess

If you will not answer the questions we post then we will stop asking them.

You said they saw the problem but did not say what they checked,
so do what I said and test when the problem shows up

 

[jeff acton]

Re: Make a guess

I have a spark testing tool which goes on any spark plug and will really light up if any spark occurs. Thanks, Jeff

 

[jeff acton]

Re: Make a guess

Sorry i was not as quick to respond as you wanted. Was away from my computer for one day. The problem will not continue at the shop long enough for any good series of test to be completed. I really don't have the needed equipment or knowledge to perform test at home.. Is it the white wire that should be diaconnected to perform test? Thanks, Jeff

 

[99yam40]

Re: Make a guess

My advice is to Pick up a Yamaha service manual for your motor and read up.
get the proper equipment for testing so that you can test when it will not spark and be ready for testing.
DVA adapter is less that $100 and can be used with a regular meter for testing peak voltage

Yes I think the white wire is the correct one for even an old motor like yours

 

[jeff acton]

Re: Make a guess

Thanks Captain, I will continue my saga and keep you posted. Jeff

 

[jeff acton]

Re: Make a guess

Just wanted to check in and report that I have found and corrected the problem I had with my motor. One of the post suggested a heat test and although I think this was if it quit after heating up. I got to thinking about a reverse situation and the only variable for me was the motor would run for the repair shop and not for me. I was thinking that it would sit out on a lot for a few days before it got in to be diagnosed and the temperatures here have been very hot. When it would sit in my garage it would cool off and not fire. I took a hair dryer and heated the CDI unit and the problem went away. I found a scrap motor and swapped the unit and I have no more problem. Strange I know but it is fixed. Thanks for all the post and interest. Jeff

 

[Triton II]

Re: Make a guess

I found a scrap motor and swapped the unit and I have no more problem. Strange I know but it is fixed. Thanks for all the post and interest. Jeff

Thanks for letting us know the problem is fixed Jeff. All too often people get help from other iboats members and we never find out the result. I think you owe Jlawsen a cold adult beverage!

TII