c115 Yamaha fuel issue

[mainefinn05]

Ive got something that has my boats lungs blocked. I have an aluminum tank and the bowl on the motor is getting something that looks like tan sand in it. Drained it into a container and once it dried it was powdery like. Now my problems set in today, rough idle, almost four stroke sound but ran fine at higher rpm. Eventually all she would do is idle rough, no transition from low speed idle ports to high speed guzzler ports. I assume i have plugged at least one if not more of my low speed ports/jets/what have you. How complicated are these Yami carbs? I rebuilt my old '71 Rude carbs without much trouble but these have more adjustments. Any ideas where this crap is coming from? My thought is to add an inline filter and always keep a freshy on hand. Just bought the boat a week ago and bummin now. Is my onboard tank cooked or is this just a varnish coming off that will clear with some filter cycles?  Stressed and bummed, don't want to pull up the decks the previous owner replaced last year.

[Capt. Bob]

I think I have a varnish coming off in the tank.  Dries to a powdery substance looks like tan sand in the bowl.  Plugged my carbs.

Ah,
Ethanol.

[mainefinn05]

Wondering if its because I treat fuel and maybe he didn't.  Hoping this will clear with filtering, otherwise I'm hoping it fits in my buddies heated garage this winter...

[Capt. Bob]

Is my onboard tank cooked or is this just a varnish coming off that will clear with some filter cycles?  Stressed and bummed, don't want to pull up the decks the previous owner replaced last year.

Sounds like ethanol has dissolved the "varnish" that is caused by non-ethanol fuel. Common occurrence when adding ethanol to an older tank that was filled with non-E. Filters will help but changing them more often is the norm. Theoretically, if you continue to use ethanol, it should dissolve all the varnish and eventually the problem would end. I had to work through this very problem several years ago on the CCP. I always carried (still do) a spare 10 micron screw-on and change when I see the first sign of debris in the bowl or once a season.  

Haven't rebuilt my Yamaha carbs yet but I can't imagine they would be any harder than other types. Getting them (or any carb) off and on is usually the tough part.

Good luck.

[wingtime]

I agree with CB sounds like and ethanol related problem.  Ethanol is a very strong solvent and like CB said it will remove the built up varnish in your fuel system.  The old varnish usually is a light tan color and is in flakes or like you said a sand like material.  You need a 10 micron water separating fuel filter if your using ethanol fuel in your boat.  Be careful you may have some blockages in your carbs now causing a lean cylinder..... which we all know is VERY bad for two strokes.

[mainefinn05]

Ya she just wasn't into going eventually.  Think it clogged my low speed jets first.  Was running like a top before, had the issue come up, cleaned it, ran great again then yesterday happened.  Pulling off the carbs tonight and they'll soak overnight in whatever I can find like gumout or something.  Encouraging to hear that this should eventually clear.  He had a water separator on it before but said it was sucking air and removed it.  I'm thinking inline since this boat dwells on its trailer and i'll be putting some fuel through her from now until winter provided I'm on target with needing a good carb cleaning. And this all started once I got the boat and was putting pump gas through it.  Maybe he was paying docks prices for non-E?

[Skoot]

In other news I was towed in yesterday.  Tank issue.  I think I have a varnish coming off in the tank.  Dries to a powdery substance looks like tan sand in the bowl.  Plugged my carbs.  How tricky are these yami carbs?  I have done an old '71 johnson before.

 Has the fuel tank ever been replaced?  If not its defiantly time for a new one.  My tank had the same issues when I bought the boat.  I debated having the tank cleaned, keeping additional filters on-board, etc etc to try and clear up the problem.  After further inspection of the tank, I noticed there was alot more wrong with it than just varnish coming off.  I would strongly suggest installing a new tank if it hasn't been done withing the last 35+ years.

Here's a link to my tank replacement thread.  viewtopic.php?f=1&t=5174

[mainefinn05]

Skoot, unfortunately when the previous owner redid the decks he eliminated the fuel cell hatch.  He claimed the tank looked fine, it's a 40gal tank, was this standard on a 19-6? My tank also has a float gauge on it that I look at through a clear hatch just under the console.  I have a dry bilge and no odors.

[Skoot]

You wont really know without inspecting it yourself.  What I can tell you is that if its the original tank, it needs to be replaced.  Anyway to find out how old the tank is??

I think the standard tank size for our boats was 50 gals.  Not to say someone requested or replaced the tank @ 40 gals.  My new tank is appox 45 gallons.

I dont blame you not wanting to rip up the existing floor.  Your only other option would be to install a new tank under the center console as there is a lot of room under there.  This was the standard tank placement for the AS 19-1's.  You would lose most of the storage space but you could probably fit a 30-40 gal tank under there.

[mainefinn05]

Skoot, I'll check it out.  There is a visible label on the top of the tank.  Have a dreading feeling this may become a winter project provided this thing fits in my buddies heated garage.  I've done decks before, but this one was done right and could be a real PITA to get up unless I try and figure out my tank dimensions then cut out a new hatch.

[wingtime]

If your running pump gas with ethanol you NEED a 10 micron water separating spin on type filter.  They don't cost much and they can save you a ton of headaches.  The only way the old on was sucking air is if it had a hole in it or something.

[mainefinn05]

Makes sense, just hoping to get through this without taking out the old tank.  Previous owner removed the fuel cell hatch when he rebuilt the floors.

[flounderpounder225]

If, and only if you discover your tank is in good shape, and does not need replacing.  I would highly recommend taking the boat to a fuel cleaning/polishing service, with a small tank like that, it would be relatively cheap, and end your particulate contamination issues completely.  Then get the good 10 Micron spin on filter, and your set.

[mainefinn05]

Carbs were nasty. No idea if they're set right yet. Friday I will add some filtration. Pumped off the tank, got some gunk. Will dragged it around the block and try for some more.  I have a pretty good idea I will be budgeting for a new tank/floor for sometime this winter. Guess i should have expected this for the price.  

[mainefinn05]

BTW top carb was set at 1 1/8 turns out on the screws and the bottom was 3/4 and 5/8.  Is this right? I set the bottoms to the top but i guess ill find out, looking for some explanation or guidance.