Motor Still Surging @ Revolutions Above 3000 RPM's

[CaptainSteve75]

Re: Motor Still Surging @ Revolutions Above 3000 RPM's

Ok, wait to hear this one...I was able to finish testing the ignition system with my DVA meter (Thanks to Rodbolt). @ 1500 to 2000 lost spark at cyl 1 and 2. @ 2500 to 3000 cyl 3 and 4. I notice the cable from the CDI to reomte control was interupted (cut and spliced) with a similar color coded wire which led to the yamaha 703 control box. What a mess!!! Test wires and found the yellow wire had a return voltage (Remote to CDI) of 12V. But the voltage for the yellow wire from CDI to remote had no voltage,

I went ahead and started the engine with the yellow wire disconnected the surging stopped...WTF???

Can anybody tell me why?

 

[rodbolt]

Re: Motor Still Surging @ Revolutions Above 3000 RPM's

because the ECU is now in bypass mode and only uses the pulser coil signal.
must have 12V on the yellow wire and a CPS input signal to spark all 6 correctly.

 

[99yam40]

Re: Motor Still Surging @ Revolutions Above 3000 RPM's

How did you determine the loss of spark? With the DVA? Where did you measure and what voltage did you get?

Did you measure the inputs to the CDI/ ECU also or just the outputs?

Troubleshooting with the correct tools and following the step by step procedures in the manual makes things go smoother and faster, as you have found out swapping parts does not really tell you much and takes a lot of unnecessary time playing with things that are not broke.

 

[CaptainSteve75]

Re: Motor Still Surging @ Revolutions Above 3000 RPM's

Yam: 21v on a 400 scale: B and BW wires from CDI Output to Coil Pack with DVA

Rod: Just to confirm 12 V coming from Remote Control Box to CDI and not in opposite direction. Now remember I am learning here. What is the purpose of the yellow giving a return voltage to the CDI...you metioned CPS, is there anything else?

What should I continue to troubleshoot?

 

[99yam40]

Re: Motor Still Surging @ Revolutions Above 3000 RPM's

Did you check the input voltages? You need to know there is voltage going in before you can tell what is causing no voltage out.
like #2 post said this needs to be tested in gear not neutral. Maybe a problem with neutral switch

 

[rodbolt]

Re: Motor Still Surging @ Revolutions Above 3000 RPM's

no return voltage on any yellow wire under the hood.
if the key is on any yellow wire will have 12V to ground or something broke.

 

[CaptainSteve75]

Re: Motor Still Surging @ Revolutions Above 3000 RPM's

Did not performed with DVA refering to post #2 at the time...But I did perform with DVA at fast idle with water tank for pressure and still dropped spark on 1,2,3,4. Over Rev was ruled out recently

When I disconnected yellow wire as previously mentioned and went for a test run, all six cylinders fired confired with DVA at WOT engine ran fine.

Now I do need to measure the inputs to the CDI with the DVA, I tried doing the paper clip technique and did not work out the first time I tried it. I need to try this again...

Prior to DVA, the fact that I swapped out those parts previously mention (CPS, Pulser Coil, Stator Coil)...can I eliminate these components from being defective.