Yamaha f20 quits

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Dxdog

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Took my new Yamaha 20 out for the first time on Friday. Break in procedures recommend not running it wide open for the first ten hours. I ran it about 5 hours at varying speeds. At slower speeds (about 1/4 throttle) it would run great. When I ran it between 1/2 and 3/4 throttle for 5 mins or so it would sputter a couple of times and die. It would fire right back up and off I could go, but if I ran it like that again it would sputter and quit.

I was using new 93 octane gas without ethanol. It's a new Atwood 6 gal tank. One thing I wasn't sure on was the ventilation of the tank. Since it doesn't have a designated vent, I opened the fill cap. I frequently checked if the tank was concaving or building pressure and it wasn't. It sure feels like an air/fuel issue, but I'm not sure what to check/do.

It doesn't feel heat related since it started right back up. And the water temp was about 33 and air temp was around 50.

Any suggestions?
 
What fuel line are you using? I ASSume it's the factory Yamaha fuel line. What fittings are on the tank? Does it have a "demand valve"? Have you possibly checked for water in the fuel?

I asked those first because most of the time warranty will not cover fuel issues, unless there is a problem with the carburetor, fuel pump, or any other factory installed part.

Depending on when your motor was manufactured, the newer ones (April 2011 and newer) have a round fuel connector, both at the motor end of the fuel line and at the tank end. Most dealers sell the aftermarket tanks because the Yamaha tank costs a good bit more....BUT the aftermarket has not yet caught up and the "round" connector fitting is not yet available. So what most dealers do is to cut the end off of the fuel line and install a standard Yamaha/Mercury "old style" fitting, as well as a demand valve and the proper fitting into the tank. I've seen the demand valves fail. Often. Joke if you ask me. And Yamaha doesn't cover those....it's something that the dealer is responsible for. That is why I like to sell Yamaha tanks only, although I leave the option open for Attwood because they are cheaper. After all the fittings are installed and the EPA compliant fuel line is tampered with, the price difference is negligible. And in 22 years, I've not had a single issue with Yamaha's tanks; not even the EPA low-perm tanks.

I also tend to sell a 3 gal tank to most people who are buying a 50 HP and under. If you're a "normal" boater (weekends mostly, not having to run wide open for hours on end) a 3 gal tank works fine. Problem I have seen is that with 6 gallons, the fuel gets old before it gets burned. Even happens with mine-and I run 3 gallon tank; but I don't get out on the water as often as I'd like. I'll burn a gallon to a gallon and a half, then dump the rest into the truck when I'm done, and refill the tank next time I'm ready to head to the water.
 
Sorry for the late reply. we've been dealing with power outages up here due to an ice storm and 6+ inches of snow. :(

Running 92 octane fuel without ethenol. I'm as sure as I can be that there is no water in the tank. It was a new tank. Motor was manufactured in 2010 and came with a factory Yamaha fuel line/bulb. I bought and put on a brass Yamaha end on the tank. I'm not sure if it has a "demand valve"...how can I tell? I also wasn't aware that those fuel lines/bulbs have a certain way to hook up - since both connector ends were the same I assumed they could be hooked up either way.

I appreciate all the help. I'm pretty new to all of this and this site has been great! I want to make sure it's not something simple that I can fix/correct before taking it in to the dealer....they are crazy busy this time of year.
 
Found the problem. It was indeed that I had the fuel line/bulb hooked up in the wrong direction. I feel so dumb. Also, relieved that it wasn't something more serious. I took it out for a few hours yesterday afternoon and it worked great. (Although I about froze). 36 degrees and coveralls takes some of the fun out of boating. Thanks for all your help!
 
Hey at least you have open water. There is still 30" of ice in these parts and it's going no where fast! Any boating is better than no boating!
 
Glad you found your issue!

Trust me....I'm a tech and I'm also a customer (I own a couple boats/motors myself). You're not the only one who's done that ;)

Demand valves....https://www.google.com/imgres?imgurl=https://www.attwoodmarine.com/UserFiles/Store/Product/Images/1413/full/9300FDV7-S_fu.jpg&imgrefurl=https://www.attwoodmarine.com/store/product/portable-fuel/fuel-demand-valve&h=519&w=600&sz=25&tbnid=uzFWz2774nZgcM:&tbnh=90&tbnw=104&prev=/search%3Fq%3Dfuel%2Bdemand%2Bvalve%2Boutboard%26tbm%3Disch%26tbo%3Du&zoom=1&q=fuel+demand+valve+outboard&usg=__5PeYI39qg-np6Qh1FPQY8XIMGo0=&docid=RZCFDC0N0sU-VM&hl=en&sa=X&ei=VFZzUeysL6nk2wXu4oFI&ved=0CE0Q9QEwBQ&dur=1593

It's supposed to keep fuel from flowing to the motor when the engine is not running. It's supposed to go in the fuel line, inline between the tank and motor. I've never seen one that actually works like it's supposed to.

The EPA mandated low-permeation fuel lines and fuel tanks in early 2011-which is why Yamaha changed their fuel line fitting style. The new style fitting stops fuel flow before it's disconnected (mandated by the good old EPA) so that no fuel will drip or spray out, which is supposed to help with evaporative emissions. They also changed the line itself to a low-permeation material. I like it-it's more flexible and seems like it doesn't get hard over the years of use like the old style lines did. And I like the connector as it's a simple push/turn operation rather than a squeeze the lever, fight with a stuck pin, pull out (and sometimes pull apart) ordeal with the old style. But, It's like $50 for a fuel line. And about $100 for their fuel tank which has the correct fitting for the "round" fuel line connectors. Most guys cut the round connector off of the Yamaha original fuel line, then clamp a typical "old style" yamaha/mercury/mariner fitting to the new style low-perm line. The problem lies in the fact that the aftermarket has not caught up yet. Noone offers the EPA 2011 round-style connector with a 1/4" fitting to screw into the normal aftermarket tank. So what most guys do is to cut the round connector off and clamp an old style mariner/mercury/yamaha fitting onto the fuel line, then screw in a matching merc/mariner/yamaha 1/4" NPT brass fitting into the tank. The problem lies in that when that fuel line is disconnected, since the low-perm tanks DO SWELL UP (and build pressure) fuel can spray out. The idea behind the demand valve was to prevent it from spraying all over when the line is disconnected at the motor. But it adds another avenue for failure, in my opinion. I've seen a couple have problems. We aren't supposed to change the fittings on the lines per EPA guidelines. We at the dealer sell Yamaha fuel tanks, and give customers the option for the attwood....but they have to buy/install all the fittings. The aftermarket really needs to catch up.....that or yamaha can make a 1/4" NPT screw-in fitting for the "round" style connectors. Thus far, neither has taken place.

BTW-lawn mowers also are mandated to the new EPA low-perm fuel tanks. Price has gone up because the tanks cost more to manufacture. And they can't be vented like they used to. So now we have tanks that swell. And if the belt(s) are anywhere near a fuel tank, and the tank swells, there is contact...and the belt(s) can wear holes into the tank itself. So some manufacturers have added a valve which leads to a carbon canister-identical to what cars have had to use for the last 40 some years. If you ask me, it's ridiculous.
 

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