30hp 3cyl, cyl 2 dead

[walleyehunter13]

Got a 2001 30hp 3 cyl 2 stroke mshz oil injected

If I pull the plug wire on cylinder 2 there is no change. It runs a bit rough at idle, gets really rough and shakes up until I'm out of the lower rpm range and I presume off the idle circuit and on the main circuit.

Compression is 135, 135, 130 on my snap off comp tester (haven't been calibrated in 10 years but the difference between is a that really matters anyways)

Spark gap tester set at 1mm produces blue spark on all cylinders, and timing light shows all cylinders firing properly.tried switching coils around to see if any difference and problem stayed on cyl 2. Tried a fresh plug and same problem

I've just got done thorough cleaning the carb once again. Soaked it for an hour, then went through all the passages with copper wire, then blew out with my compressor. Repeated this 3 times to make sure I got anything g that could have been a problem. Still made no difference. Floats are a set in spec per manual. Floats not sticking at all, closes completely when. Blowing into it upside down.

Not sure if I'm just not getting gas to cyl 2, or if to much gas and it's over killing the a/f ratio? I see u burnt gas in the exhaust. If I close the choke on cyl 2 only the motor starts to stumble and eventual dies

Running out of ideas on what to test.

this cylinders carb is also where the fuel pump is. I replaced the diaphragms a few weeks ago thinking that was the problem but that changed nothing also. I did notice rust behind the diaphragms and I cleaned that all out but didn't notice any rust in the carb bowl. The bowl is full of fuel so I take if the pump is doing its job.

Any more suggestions?

[cpostis]

You might want to check your pilot screws (especially # 2) and adjustment thereof. If a pilot screw was over-tightened , it could be damaged.

If you have a manual for your motor it should show the # of turns the screws should be turned out for each carb. Idle speed adjustment should be done after this.

Here is a chart from a 1998 model year service manual, yours may be different. Do you have one?

[IMG]Pilot Screw by Charles Postis, on Flickr[/IMG]

I'm not the carb guy on this forum. Maybe our friend Townsends will ring in?

[ausnoelm]

Hang on, you say you have spark on all cylinders, but then you changed coils to see if it made a difference! How was it going to change anything? You have spark.....you said.

[ausnoelm]

OH, and kind of doubt it is your pilot screws! but you never know I guess, they only affect idle, you say it is still rough even above idle!

[boscoe99]

Using an atomizer, spritz a bit of gasoline into the intake of the number two carburetor while the motor is running to see if it picks up and runs better, or stays the same/gets worse. If it picks up it is telling you that the carburetor is not doing what it is supposed to be doing.

[walleyehunter13]

My manual says the same for the pilot screws. Seems like the problem is either idle circuit related or vaccuum leak. It disappears once I put some rpms into it. Doesn't matter how many turns I do, #2 is just not combusting.

I switched coils around just to assure myself that's not the problem. Only 2 bolts and 1 plug.

When I get more time I'm going to take a mini propane torch and slowly trickle gas around the carb to see if maybe I got a leak somewhere.

Also...the spark I was seeing, it was blue at the contact points and white between the blue sparks. That's alright, right? Not sure how proper spark is supposed to look, just knew I was supposed to see blue and not orange

[walleyehunter13]

Using an atomizer, spritz a bit of gasoline into the intake of the number two carburetor while the motor is running to see if it picks up and runs better, or stays the same/gets worse. If it picks up it is telling you that the carburetor is not doing what it is supposed to be doing.

And if it doesnt, or gets worse then I'm getting to much fuel, right?

[ausnoelm]

Don't know exactly what you mean, but mini propane torch, and trickling gas doesn't sound like something I would be too thrilled about doing to my motor!

[boscoe99]

Don't know exactly what you mean, but mini propane torch, and trickling gas doesn't sound like something I would be too thrilled about doing to my motor!

Not thrilling but not harmful if one pays attention.

If an intake leak is causing a motor to run ruff then gently providing a bit of propane in the area of the suspected leak will cause the motor to run better if and when the motor sucks in some fuel and not air via the leak. A bit of propane into the inlet of the carburetor can be substituted for the spritzing of gasoline. Done by mechanics all around the world quite commonly.

[boscoe99]

And if it doesnt, or gets worse then I'm getting to much fuel, right?

If the carburetor running overly lean then adding some extra gasoline will cause it to run better. If the carburetor is running overly rich, to the point that combustion is not taking place, then adding a bit of extra gasoline won't make it worse, it just won't make it better.

Have you tried pumping the primer ball while inspecting the inlet of the carburetor to see if fuel is being dumped into the carburetor? Perhaps the inlet valve is not closing and is dumping extra gasoline into the carburetor.

It is a bit of shame that all three carburetors are different so that the positions could not be swapped around a bit as a trouble shooting measure. Like what you did with the coil. I trust that when you swapped the coil that you also swapped out the lead, the cap and the spark plug.

[walleyehunter13]

The wires and cap are all part of the coil on these. I made sure to change out the connection so it was getting voltage at the right time from the cdi. Had brand new plugs in too to make sure they weren't fouled up.
I was hoping it was just the coil to be honest, because I've cleaned this carb 5 times now because everyone keeps suggesting it's the idle circuit.
I'll hit it with a mini propane pen torch tomorrow and report back. I'm sure it's something stupid (I'm hoping) and not a major repair needed problem.

[99yam40]

can you feel any spit back from carb #2 like the reed is not seating properly or cracked?

Like was posted before try enriching with propane or a spray bottle of fuel misted into #2 carb to see it that helps.

I have read about but not tried it before, to pinch off the fuel line to #2 carb to stave it for fuel to see if that will get #2 to hit again.

Does no make sense to me that closing the choke on only #2 carb will cause motor to stumble and die if #2 is not firing properly at idle anyway

[TownsendsFJR1300]

Just for S&G's, plug that new spark plug (please test that plug to verify it IS good) into #2 wire and ground the plug to block.

With the plug properly gapped, crank up the engine and see if that plug is indeed firing when running. (I know your getting spark thru the wire, but the cap may be bad.)

And on the carb cleaning, did you PULL ALL THE JETS to see light thru them?

To rule out #2 carb flooding / bad float. Pull off #2 carb, remove the bowl, hold upside down then attach a short fuel line to it to make sure the needle and seat are sealing FULLY. If you have a small vacuum tool(brake bleeder will work), it should also hold a vacuum when pulling from the intake fuel nipple. If it doesn't, fuel is getting past the needle seat, flooding that cylinder, fouling the plug, excess un-burnt fuel coming out the exhaust..

Did you check the float to make it didn't have any leaks?-ie hold under water, look for bubbles or shake and listen for fluid inside). That would cause the same issues ^^^^

[walleyehunter13]

Propane in #2 throat did nothing. Also checked all the gasket areas with it and no rpm change.
When I checked the spark I was using an adjustable gap tester that was grounded to the block and I was seeing blue/white spark, and the spark looked the same on every cylinder.
I pulled all the Jets except for the ones not listed in the parts diagram that are on the topside of the carb under a rubber flap. I did run a wire and blow them out real good though. Didn't pull those because when I tried getting my screw driver in there they didn't want to budge and if I damaged them I don't see any kind of replacement part listed for them. They are under #16 plug in the carb parts listing
2001 30MSHZ Yamaha Outboard CARBURETOR Diagram and Parts

As for the reeds, don't notice any spitting, put my hand over the carbs and they are all sucking and not blowing.
I did notice gas is all over the bottom of carb 2 now. I used all fresh gaskets and carb kit when I cleaned the carbs a month ago. Maybe my bowl isn't seating the gasket properly, or maybe the float is bad like you said or isn't seating the needle and it's coming back up the throat. I'll go check try priming the bulb and seeing if it's letting gas through
I'll try grounding a fresh plug just to confirm your suspicions. I won't be able to pull the carbs off again until next Friday though.

[TownsendsFJR1300]

Jets 12 and 35 are the main ones that cause issues. If you got those out and all the tiny holes are clear, their good...

It sounds like #2 carb is flooding out fouling the plug / cylinder.

It doesn't happen often (as read here), but on occasion the seat (and needle wear out). I have personally seen several floats leak as well...

The easiest way to check #2 is to flip it upside down so the float is closed, then put a vacuum gauge on the fuel inlet. IT SHOULD hold a vacuum..

Of course the float, hold under water, or shake it.

Also, double check the needle to float relationship, that all is correct.


That leaking now on #2, is telling you where the problem is...