F200txra ignition coil for 2&5 burned up, including main relay, and fuse

[mokaction]

Hi guys,
Have not been on here for a while, my f200trxa has been working great for the last couple of years then 2 weeks ago I was going back from a trip and my engines started to miss firer and once I got it to the dock it shut down.

The next day I was able to take the cowling off and noticed a burned smell coming from under the spark-plug/coil cover. Also when I turned the key the fuel pump and tachometer lights were not on.
What I found was:

1. 2&5 coil was burned to a toast and coil plate, the bottom coil. Pic attached
2. Main relay was also fried
3. 20 amp fuse was also burned out (red/red and yellow wire).

I have an extra Main relay and fuse, but didn't have the coil, so I ordered a new coil from boats.net. Then I installed:

1. Main relay
2. 20 amp fuse
3. I removed all the wires to the other coils and spark plug wires to test the main relay


I turned the key on the ignition switch and now I could hear the fuel pump and the lights turned on the tachometer.

I waited for the parts to come in from boats.net. Then I installed the new bottom coil and put all the covers on.

The motor started right up, but was miss firing. Then I turned it off and the new coil was burned up again. Also the fuse burned out again.
I am so frustrated, any help would be appreciated

[boscoe99]

First thing that I would check is the ground wire for the coil. The black wire with the white tracer. Verify that it is not grounded to the block.

It should only be grounded when the ECU commands it to be grounded. If the wire is shorted to ground then excess current will flow through the coil and damage it.

[rodbolt17]

this s gonna sound funny but I have seen it more than once.
a stuck ISC valve overcurrents the ECU and fries coils,ECU's and various other item.

I have also seen ECU failures that pop the 20 amp ign fuse at key on.

remember any wire that is yellow/red is 12V+ at key on.
this includes injectors,ISC,coils and fuel pumps.

[boscoe99]

You are absolutely correct that a failed ISC can result in damage to an ECU. A damaged ECU in turn might cause damage to other components.

I would have to say that an ISC that can draw excessive current, and in so doing damages other parts, is a design deficiency. Would you agree or disagree?

Seems there should have been some circuit protection of some sort built into the system. Either a fuse, a CB, a fusible link, or some device that can limit X current from flowing longer than Y time should have been incorporated into the system. In aerospace this would have been addressed in a failure modes and effects analysis. Apparently Yamaha does not do this.

For the sake of the OP, I am hoping that he just has a wire that is shorted to ground. Otherwise, the repair is going to get expensive in a hurry.

It is hell when the core problem being in one component manifests itself in the failure of a different component. ISC takes out the ECU. ECU is confirmed as having failed. ECU gets replaced. Old existing ISC takes out the new ECU. $$$$$$$$$$$

[mokaction]

I will check for a short first and also check the ISC. I am praying that it is not the ECU, there goes my credit card again.. LOL..

Robolt and Boscoe, Thank you so much for the reply, the little boy inside me was coming out and I was so frustrated yesterday. It is so nice to know that I have someone watching my back.

[mokaction]

Where is the ISC valve located???

[boscoe99]

[mokaction]

Thank you Boscoe.. Will remove it and check it out..

[mokaction]

i checked the coil wire and it was good. took off the ISC and there was carbine coated. also the center part was frozen. cleaned it will some carb cleaner, also order another coil. will test it once i get the coil and post results.

[greasyshaft]

When you disconnect the kill lanyard or turn the key off you should hear the ISC rattle (resetting in anticipation for next start-up)

[99yam40]

i checked the coil wire and it was good. took off the ISC and there was carbine coated. also the center part was frozen. cleaned it will some carb cleaner, also order another coil. will test it once i get the coil and post results.

may want to get a new ISC , not just clean it if it has been smoking other parts

[mokaction]

I think you are right. I am getting the new YDS Software and should be here sometime this weekend.

Not sure if I should add this on this thread, but attached is a picture that I had a question on.

1. I circled in red in the diagram the junction box, does this mean that all the wires are in series?? So my question is, I should be getting connectivity on all red and yellow wires??

2. Or do I just get a 12v on all the read and yellow wires when I have the power turn on??

3. I check the connectivity on the wires going to the coils, and when the ecm is not hooked up, I found that when I put the ohm meter terminals on the connector to the ecm and to the end of the neg coil wire that I get connectivity, but when I hook up the ecm and then put the ohm meter terminals on the neg and the motor ground that I am getting some resistanta. Could this be a issue??

Thanks in advance.

[rodbolt17]

STOP
put the meter down.
back away slowly.
do some BASIC reading on series and parallel DC circuits.
there are some laws that apply to both VOLTAGE and RESISTANCE tests in parallel and series circuits.
that junction box is simply that.
there is another that gangs a bunch of grounds.
I will say it ONE more time.
if that wire is yellow/red, its 12V + anytime the key is on.
almost ALL Yamaha functions are GROUND path con*****ed by the ECU.

the ISC has 12V applied anytime the key is on.
the ECU controls the ground path to make the stepper motor turn CW or CCW.
the ECU does not and cannot monitor the ISC.
it simply applies the ground to make the idle RPM change.
if the ISC sticks the ECU sees it as an idle RPM issue and keeps toggling the ground path.
this leads to excessive current and excessive heat in the ECU.
this is about the time the ECU has a heat stroke and goes brain stupid.

this is when the ECU turns on the transistors that control the ign coil ground path allowing the coil to overheat and die.

remember the fuel pumps,ign coils,injectors and a few other things have 12V+ applied anytime the key is on.
the ECU controls the ground path.

remember, voltage is simply a measurement of electrical pressure.
voltage DOES NOT FLOW.
CURRENT flows and is measured in amps.
the ground path MUST be complete or NO current flows.
no flow no device works.
when checking resistance you MUST isolate the circuit to avoid erroneous readings.
but shorts are easy to find, that's where the smoke got let out.
odds are high you have no shorts but a stuck ISC can kill ECU's,coils and harness's.

[boscoe99]

I think you are right. I am getting the new YDS Software and should be here sometime this weekend.

Not sure if I should add this on this thread, but attached is a picture that I had a question on.

1. I circled in red in the diagram the junction box, does this mean that all the wires are in series?? So my question is, I should be getting connectivity on all red and yellow wires??

Just the opposite. They are connected in parallel. The diagram is just showing you a common connection point where all of the R/Y wires come together. Think of an extension cord with a male connector at one end and 10 female connectors at the other end. The male connector gets plugged into a house outlet. The female connectors all have ten male connectors plugged in that go to electrical devices. All of the devices are sharing the same power supply. The same as the connection point (a junction box) on your motor.

2. Or do I just get a 12v on all the read and yellow wires when I have the power turn on??

Yellow is normally the wire colour in a Yamaha that is considered key on power. This wire is powered when the key is on and not powered when the key is off. However, within the engine harness Yamaha will use a red wire with a yellow tracer to also indicate key on power.

3. I check the connectivity on the wires going to the coils, and when the ecm is not hooked up, I found that when I put the ohm meter terminals on the connector to the ecm and to the end of the neg coil wire that I get connectivity, but when I hook up the ecm and then put the ohm meter terminals on the neg and the motor ground that I am getting some resistanta. Could this be a issue??

Having connectivity is fine. But you can also have a wire shorted to ground (bad) and have connectivity of the wire at the same time. Why are you using the Ohms setting on your multimeter? Are you testing for resistance or are you testing for connectivity?

Thanks in advance.

See my comments above.

Do you not have a trained marine mechanic that you can work with to help show you how to do various tests? This can be a very useful training session for you. We have all needed some help from others as we go through life. Getting it over the inner web is not the ideal situation.

[rodbolt17]

sometimes internet info is suspect at best.
kinda like neighbors and beer buds assisting.

I am rebuilding a 95 50 evinrude gearcase now due to a neighbor assist.

work order said check shifting and adjust.
that was my FIRST giggle session as once adjusted, unless something breaks,cables like ign timing NEVER need adjustments.

so I pops the ole shifty cable loose and start manually shifting the motor.
whoa way to much lost motion in the shift rod.
a careful visual shows the issue.
someone has removed the shift lever screw on the side of the gearcase.
I can see the screwdriver marks.

so I remove and disassemble the case.
sure enough the lever and cradle have parted ways.

the kicker you ask?
in the process of changing the water pump and driveshaft seals the beer bud installed the driveshaft thrust bearing shim between the bearing and the thrust washer.
that explained the liquid metal oil drain.
lucky for this guy it only munched the fwd,rev and pinion thrust bearings. it also munched one of the pinion thrust washers and the shift cradle.
I figure that neighborly help just set the guy back about 600 bucks give or take.

so its your motor just be careful.