30hp 3cyl, cyl 2 dead

[TownsendsFJR1300]

Quote:
"Also noticed some arcing between the intake and crankcase but I don't think that has anything to do with my problem since I'm seeing good spark."


Where specifically?

You shouldn't be seeing ANY ARCING, PERIOD.

Can you take / post a pic pointing at where the arc is occurring?

If possible, run the engine in a DARK AREA(on muffs). Any arcing will be easier to see.
.

Your getting close...


Agreed, that isn't much leakage, but it is an air leak, leaning out that cylinder(bad).

[rodbolt17]

why not simply make a 3 spark tester?
much better than trying to ground a plug.
it is easy to make I posted one some years back.
can be found on google.

if your not seeing gasoline comeing out the throat,coming out the airvent or bubbling up the emulsion tube the only other way it can flood is a bad fuel pump.\

I have done this type work for just over 40 yrs for a living.
in that time I have worked with many EFI,DFI and carbed setups on mazda,audi,volkswagon,ford,cheverolet force,volvo penta marine,mercury/mariner/Suzuki/Honda/Tohatsu/omc/jonny/rudes and yamahas plus a few others.
NEVER in 40 +yrs have I had the need to pressure/vacuum test a needle valve.
to easy to use my eyes and the gray matter twit the ears.

Yamaha's standard is the spark has to jump a 7/1th gap at cranking speed? will yours do it?

break it down.
the ign system is actually two subsystems.
ign producing and ign con*****ing.
the fuel system has a pump,a tank,some lines, a few needle valves andsome internal passages.

fuel is moved from the bowl via a 14.7 mile high colum of air.
the a/f is moved into the crankcase via a set of one way valves on a two stroke carbed Yamaha.
from there the engine is actually 3 engines on a common crank.

this stuff aint hard and the tech is very old and well proven and sim[ple to test.
having the correct test equipment coupled with understanding of each engines subsystems makes your engine a 20 min diagnoses and a couple hour repair.

[walleyehunter13]

Quote:
"Also noticed some arcing between the intake and crankcase but I don't think that has anything to do with my problem since I'm seeing good spark."


Where specifically?

You shouldn't be seeing ANY ARCING, PERIOD.

Can you take / post a pic pointing at where the arc is occurring?

If possible, run the engine in a DARK AREA(on muffs). Any arcing will be easier to see.
.

Your getting close...


Agreed, that isn't much leakage, but it is an air leak, leaning out that cylinder(bad).

The arc is at the tip of the round part I'm trying to circle
It's jumping between the crankcase and intake








As for rodbolt spark tester, I've been go ogling over an hour now trying to find do it, anyone wanna throw me a bone on that.

[TownsendsFJR1300]

What wiring is right there???

The arcing should be leaving some evidence of small brownish/black reside as it jumps... Follow where the wire goes to / from, besides repairing it. Pull gently as well looking for ANY pinched wires.

Start poking closer and see what bare wires, worn insulation, etc is going on in that area.. Somethings getting energized /shorting out.

A good, strong flashlight should help.

No blown fuses???

[rodbolt17]

that arcing when spark testing is due to improper testing and it can arc more than once as the current tries to get back home.

to make a tester.
take a 2x4 block or even a 1x1 about 6" long.
take a strip of metal pipe hanging tape about 9" long.
nail the strip along the edge of one side.
take as many nails as you wish to test spark on and place them 1/2-7/16ths of an inch from the tape strip.
now is where you can play.
standard wire can be used but MUST be kept away from metal.
\\
best is to use 1ft long strips of metal cored,NOT CARBON CORE, plug wire.
run a nail 1/2-7/16hs from the tape strip. nail through the center of the wire.


\
now you can add spark plug tips OR simply peel back about 1/4 inch of insulation,fold the wire back and insert into the plug cap.
screw on a radio shack clamp to the tag end of the plumbers tape and there you have it.

[walleyehunter13]

that arcing when spark testing is due to improper testing and it can arc more than once as the current tries to get back home.

This is when running the motor like noemal, not testing.

The nearest (+) wire is the cdi box.
There's nothing electrical that I can think of that's attached to the intake area.
It's getting dark out so I'll have to wait till next week again
My HOA must be ran by 90 yr Olds because once it's dark it's pretty much curfew.

Rodbolt, thanks for the explanation. I'll build it friday.


Here's a pic of the only wiring on the motor (Except the oil level sensor that runs over the top of the intake)

[rodbolt17]

my my my
if you are seeing an arc like that what would ya think thank thunk?
my first guess would be for some reason that lazy ole arse lectricity is trying to get away.
actually that is EXCATLY what it is doing.\

your system typically fires the plugs at about 7 KV.
1 KV is 1000 volts
7 Kv is 7000 volts.

7 Kv is a bunch.
the system can make about 22 Kv.
eventually spark is going someplace while on the way home.

bad plug caps can fire through the coil case.
bad grounds do stupid things.
that is why proper test equipment actually helps.

under normal running conditions you see an arc there that you think may be an ign spark.


dude
thank
that is to simple.
simply unplug the ign coil to CDI bullet connectors and see which one is creating it.
the CDI output is less than 250V.
not enough to arc.

means the arc is on one of the ign coil secondary sides.

it is simply.
suck.
squeeze.
bang.
blow.

a rich A/F mix lowers firing Kv.
a lean mix raises firing Kv.
loose plug caps or open circuit plug cap resistors, raises Kv.

eventually this KILO VOLT charge is gonna zap something.
not much current.\
very far from harmless.
but it will eventually go someplace.

[walleyehunter13]

Tested all the coils with a 1/2" gap and got a skinny bluish spark on all 3 that looked the same. Checked all the wires and I don't see any pinched or cracked or rubbing wires. I cleaned all the grounds a few months ago, went over them again and they all are clean still.

Also hooked my multimeter up to ground and put it in continuity tester mode and ran a pin hooked to the + lead over every wire and around the coils and didn't get any feed.

Also not seeing that arc I saw last week at all. Maybe it wasn't an arc but bubbling or something from the intake? It's the exact same area I was seeing wetness when I powdered everything. It looked like arc but it was such a small gap it was hard to tell.

I'll try running the motor when it gets dark, don't think the HOA will mind the noise considering it's New years eve weekend and fireworks and going off all around here.

[pstephens46]

Give 'em hell!

[walleyehunter13]

So ran it in the complete darkness, didn't see any arc at all. Did a misting with a spray bottle and tap water and nothing also.

[walleyehunter13]

Did a few more test today.
Took the air box off and held a lit cigar up to the throats and 8ncreased rpms to 1500, all carbs are suckling only, not blowing back.
Sprayed down the crank halves gasket area and intake area with soapy water to see if there's any leaks. Only area to bubble was that spot on the lower intake where I thought I saw an arc. Must have been seeing combustion blowback leaking out the gasket? Going to replace the gasket and put some fiber reeds in while I have the intake off. That leak is on cyl 3 though so I doubt it will make a difference in my cyl2 problem.

[walleyehunter13]

Thought just hit me...
If I take the carbs off but leave the gaslines hooked up and keep the floats in a closed position, then pump the priming bulb, that should be able to test if my pump diaphragms leaking into the crank right?

[TownsendsFJR1300]

Once the bowls are filled, needle closed, no more fuel should flow even priming the bulb.
I would think your "test" should work.


There's only 4 bolts holding the entire pump assembly together and it appears to be out in the open.

I'd probably just pull the cover and inspect... (check for any crap too).

[walleyehunter13]

I've pulled to cover 2 times recently. Replaced both diaphragms about a month or 2 ago, and checked again last week and they still look like new and intact.
I did notice that the 5th screw that just screws from the cover to the plastic part only, not the carb is stripped from over tightening.
Part 32 is the screw I'm talking about
2001 30MSHZ Yamaha Outboard CARBURETOR Diagram and Parts
Figured if I test it like this, if it is leaking into the vaccuum port I'll definately notice. I'll try with a vaccuum pump too to try and replicate running conditions

[walleyehunter13]

So had the intake off to get a better look at things. Reeds were all fine, dropped in ccm reeds while it was open, replaced gasket and torqued to spec. Didn't change anything.
So since I got compression, gas and spark and reeds are functioning...must be something mechanical(see: expensive) right?
Was looking up possible things that go wrong on 2 strokes and almost sounds like a crank seal
Don't understand why the middle seal would go before others.
Anyone think this sounds likely?
Also was wondering how do you pressure tedt a crankcase on a 2 stroke outboard. Don't know how to plug the tuner to prevent pressure escaping, or am I supposed to have the piston at bdc?