Yamaha ox66 150 no spark

[larsuzi1]

This is my first post on the forum. I look forward to learning about my Yamaha.

This is a 2003 150 2-stroke ox66 outboard. All of a sudden, no spark. The engine ran perfectly for the 10 years it was owned by my neighbor, and ran fine since I bought it in May. Literally, this popped up all of a sudden.

I checked the ignition switch, the neutral safety switch, and the emergency switch- all okay. The primer bulb gets firm and I checked for fuel at the rail. The batteries are fully charged- the starter turns the motor as it should. No spark at the plugs when I check with a spark plug tester.

I can't help but think, and certainly HOPE that's it's a simple problem that I am just over looking. Obviously it's a problem that's common to all 6 cylinders. Where does the voltage enter the motor from the ignition switch? Can anyone direct me to a chart of some kind detailing the sequence of operation of getting power to the ignition?

Thanks a lot.

-lars

[rodbolt17]

dont splatter gun it.
that ign system does NOT require battery voltage to operate.
it uses whats generically known as an ADI system.
Altenator Driven Ignition.

it has 6 pulser coils for triggers.
lose a pulser and you get increased idle and top speed cannot be reached.
you will lose spark on that cyl and fuel will be group injected.
some pulser coil asssy's use a common ground.
lose that ground and lose spark on all 6 cyl.
this unit type can be identified by a single black wire in the pulser coil harness.

the two charge coils supply operating voltage to the capacitors inside the ECU.

the six ign coils step up this voltage for secondary ign.

so it can be broken down to ignition PRODUCING components and ignition CONTROLING components.
lose a charge coil and you lose 1 bank.

however before we get to crazy there are some simple tests.
one is to pull the saftey lanyard and crank the engine.
you should get an audible alarm.
if not fix the alarm and retest.

the charge coils and pulser coils can be tested for resistance, I don't like that.
they can also be tested for proper output voltage with a PEAK reading multi meter or a digital meter with a DVA adapter.
much better test.

if after pulling the lanyard you DO get an audible alarm at craning you know know its NOT the stop circuit.
if you do NOT get an alarm fix the horn/alarm circuits and retest.

I have only seen 1 actual failed ECU in the 15-16 years the Ox 66 has been out and it was an issue of spark loss on 1 bank below 1800 RPM.

[Bob00729]

My 2002 was only firing on 3 of 6 cylinders. After a long diagnosis by yamaha, they determined it was the stator. Once replaces, it ran great.

[rodbolt17]

that diagnosis should have taken 15 min, 20 minutes TOPS.
a quick check with my Kv tester would have revealed 0 Kv on 3 cylinders on the same bank.
the next test would be charge coil output unloaded then loaded.
in your case the unloaded test would have failed requiring no further trouble shooting.
the key is to NOT be intimidated by a few wires and KNOWLEDGE of the system.
its funny though.
I go to school at kennasaw at least once a year and have since about 2001.
I talk to a lot of inland techs that consider a big motor an F115.
some have never seen an HPDI or an Ox66 outside the classroom.
most of what I work on here on the coast start and 150 and about 1/2 are twins.
but if you really want a frustrating setup, do a 200 hour service on a boat with triple F350s.
that suxs.
I actually did a PDI on an F2.5.
the only one I ever saw personally.
did a delivery yesterday on a new f6.
that's maybe the third I ever saw.
I see a handful of motors below the 90 HP range but not many.

[larsuzi1]

@rodbolt17- Thanks for your reply.

some pulser coil asssy's use a common ground.
lose that ground and lose spark on all 6 cyl.
this unit type can be identified by a single black wire in the pulser coil harness.

Where would the common ground be located? When you say "some use a common ground...", how can I determine if this applies to my motor?


however before we get to crazy there are some simple tests.
one is to pull the saftey lanyard and crank the engine.
you should get an audible alarm.
if not fix the alarm and retest.

I tested this and it tested okay. I also did a continuity test on the ign switch and that tested okay.

the charge coils and pulser coils can be tested for resistance, I don't like that.
they can also be tested for proper output voltage with a PEAK reading multi meter or a digital meter with a DVA adapter.
much better test.

What is the procedure for testing for output? I have a SELOC manual covering '97 - '13 motors but it is quite confusing. Where can I check continuity or voltage from the switch to the motor? I saw a diagram showing a white wire from the switch going to the engine, but where in the engine? Is that the beginning of the ign circuit?

I think I said this happened all of a sudden. Ran great one outing, wouldn't start a few days later. I can't help but think it's a simple problem, but not so simple where I can figure it out myself. I appreciate the help. Thank you.

-lars

[rodbolt17]

I will say this ONCE more.
other than shutting off the spark the IGN switch has NOTHING<NADA< JACKSQUAT to do with SPARK on that motor.
if you get an alarm cranking with the lanyard out and NO alarm cranking with the lanyard in, guess what.
we just done done ALL the testing nessasary on the harness between the switch and the ECU.

what part of a SINGLE black wire in the pulser coil harness are you having trouble understanding?????

there is a 6 OR 7 wire harness just above,behind and slightly aft of the VST.
that's going to be the pulser coil connection point.
if there are six white/colored wires in a black connector and 1 black wire that is alone you have a common ground pulser.

test between each white/colored wire to a KNOWN good ground, should see roughly 300 Ohms or so.

locate the 4 pin connector for the CHARGE COIL, its has 4
wires,brown,blue,red and black/red.
test r-br and b/r-blue.
should see about 250-300 ohms.

yes seloc can be confusing but the information is there.

at key on do you hear the high pressure pump turn on momentarily?

[larsuzi1]

Thanks for the detailed tests.

"test between each white/colored wire to a KNOWN good ground, should see roughly 300 Ohms or so."

Correct- those are the readings I got. I used a KNOWN ground for this test, but that doesn't test that the existing common ground is good? I could still have a bad common ground, right?

"locate the 4 pin connector for the CHARGE COIL, its has 4
wires,brown,blue,red and black/red.
test r-br and b/r-blue.
should see about 250-300 ohms."

I cannot locate a connector with that combination of wires

"at key on do you hear the high pressure pump turn on momentarily?"

Yeah, bulb gets firm and the pump can be heard.


Thanks again.