Yamaha ignition coils

[No more boats]

OX 66
1999
2 stroke
250 Hp
fuel injected
compression all 6 cylinders 120
Dont know model #

ran fine , week later ran like crap ,
symptoms - not able too idle , not able too throttle up stalling before I could get into gear , - backfiring , - running like i was on 3 cylinders

Port side seems OK
Starboard side , no spark cylinders 1- 3 -5 , - then there is spark on random cylinder that had none , ( using a see thru tester that I can see spark )
swapped one of the no spark coil pak from starboard too port side . It had spark ,

Going from IOs too OB new too me ,
testing equipment really nothing , test light and cheap multi tester , credit card , and weekend warrior knowledge .-

Coil paks could be original,-
aftermarket 6 pak around $ 100 bucks , for Yamaha , max HP 225 . I have the 250 , any knowledge if they can be used ,? - see individual coil paks $ 89 , still indicating max HP 225 .

Educate me ,
STATOR - R there 2 pick ups - one each side of engine
Rectifier
I went thru all visible wiring , cleaned all grounds , dielectric grease , checked and cleaned harnesses

thanks in advance

 

[racerone]

Coils do not fail sitting for a week.

 

[No more boats]

Coils do not fail sitting for a week.

never mentioned coils going bad after a week , Coils are 23 years old , was asking if the ones I see aftermarket can be used , Advertised they say perfect replacement for the yamaha OX 66 up too 225 hp , I have the 250 .HP . Majority of the coils I see on line max indicated 225 hp , A parts guy I know says they are the same ?? didnt want too buy used , I am digging in this week . Fairly common problem on these older OX 66 , computer , stator , or something simple behind computer like a loose wire ,

 

[wmgeorge]

Before I went off on a chase, I would remove all the old fuel and then replace the fuel filter, then all new gas no Ethanol and I use premium with stabil added but do whatever. Can gas go bad in a week? Yeah if you have water, rust or bad gas to start with in the tank.

 

[No more boats]

FOLLOW UP - FOUND IT - engine running on 3 cylinders . My first thoughts was water , but entire bank starboard had no spark, Checked every harness connection , opened every ground , wire brushed, dielectic grease, stator ? magnetic pick up ? thought I had computer but find out its called CDI - controls spark , started too remove CDI check wiring , noticed yellow wire in harness. bullet connector , Pulled it apart , loaded with salt crud contacts were falling apart , , cleaned , new connectors , THAT WAS IT , NOW HAVE SPARK ALL 3 .,
still not sure about ignition coils , plug wires ( not all ) separating from boot , Twist back , working in that area i find plug wire dangling out of boot , don't know if they are producing proper volts too plug . I test with lighted plug tester , evenings , looks like spark is not as bright as they should . My only tester is a cheap O - harbor freight multi meter , Put it on 200 oms , reads moments then drops too 0 . I am learning about this engine , still need more knowledge and better testing equipment

 

[racerone]

Inspecting stuff is cheaper than throwing parts at a motor.

 

[wmgeorge]

My only tester is a cheap O - harbor freight multi meter , Put it on 200 oms , reads moments then drops too 0 . I am learning about this engine , still need more knowledge and better testing equipment.

FYI Ohm meters are not used for voltage just Resistance in a circuit or device. Volt meters are for Voltage and set on either AC or DC a $250 Fluke meter will not help if you do not know the basics.

 

[No more boats]

Boaters helping boaters . That's the beauty of this forum ,
Unless you ask questions one will never learn ,

OB new for me ( downsizing ) Having twin IOs learning as I go
Correcting no spark on 3 cylinders starboard side ,
I wanted too check coils . not eager too replace if not needed ,

what is correct bench testing too see if coils and wires are putting out proper volts
engine running

thank U

thanks

 

[wmgeorge]

They make a special meter attachment for doing that checking on the engine and I do not know that answer. Maybe someone who is more experienced than me can clue you in.

 

[99yam40]

they make and sell Peak reading voltage meters made for taking reading on these CDI ignition systems.
take reading on the inputs and outputs of the CDI.

Or a DVA adapter with a regular voltmeter.

If you want to take reading on the outputs of the coils heading to the spark plugs you would need a KV tester to read the high voltage

 

[No more boats]

Proper testing equipment , TOOLS OF THE TRADE ,
do this for a living buy the best , Weekenders use once pay hundreds never using again , or can't find it if you need it ,
hire the guy , if you can find one , ( sometimes educated guess on part needed ) cheaper then hiring the guy ,

I am finding with this Yamaha repair shops will not work on older engines , which forces one too do their own repairs , So much easier working on these engines then the IOs i had previous boat
thanks for the info

 

[wmgeorge]

I would just buy the needed attachment and do the testing and then you have it for next time. With the Internet today you can always sell it when your done. In fact I would look on FB Marketplace or Craigslist.... whatever for a good used one. Even Dennis Kirk has them... https://www.denniskirk.com/rmstator...erm=4585100934281230&utm_content=All+Products