Coughing, Sputtering and Eventually Dying…Not me, my Yamaha

Post by **rseas** » Mon May 24, 2010 10:11 am

I run a 2009 Yamaha 20 4-stroke. It is tiller steering and manual start. Overall it is a great motor, usually starts on the first pull, is quite and is incredibly fuel efficient. Lately though…it will not idle in gear for any length of time. It will idle all day long out of gear and runs smoothly at cruise speed but after a few minutes in gear and at idle it starts coughing, sputtering and eventually dies. It re-starts on the first pull but the idle problem continues. After I run it at speed for a few minutes it will idle smoothly again but shortly there after…

I have two questions:

1) Has anybody experienced this or does anybody have any thoughts on resolving the problem? Being a 4 stroke this motor should idle forever. Would installing a different temperature range spark plug help? Any help with this will be appreciated.

2) Is there a 12 volt charging kit available for the manual start version of the Yamaha 20 4-stroke?

Post by **G-Man** » Mon May 24, 2010 10:26 am

A 2009 motor is doing this? My first thought is bad fuel/water in the fuel. Purge all the fuel out of the tank, lines and engine. Put some fresh gas, treated with stablizer, in the tank and run it hard for a bit. If that doesn't cure the problem, take it to a dealer, it should still be under warranty.

FishingFool · Post by **FishingFool** » Mon May 24, 2010 11:36 am

sounds like bad gas or something along that line.

jbball50 · Post by **jbball50** » Mon May 24, 2010 12:19 pm

We've had this problem before but it's an older engine on the little boat. Like others said try looking at the gas line and such. We had trouble earlier this year with it idling and it even going into gear and it kept shutting down but cleaned the carburetor and it's been working good ever since.

Matt · Post by **Matt** » Mon May 24, 2010 12:28 pm

I have had this problem a number of times. Water in the fuel system. As stated drain all lines and restart.

Eddie L · Post by **Eddie L** » Mon May 24, 2010 7:32 pm

Matt wrote:I have had this problem a number of times. Water in the fuel system. As stated drain all lines and restart.

Same problem on my outboard motor, found water in my fuel filter that is mounted on the side of the motor.

produce2troutcat · Post by **produce2troutcat** » Mon May 24, 2010 8:08 pm

Just went through this with my 30hp
4 stroke mercury.I had to clean the carbs , drain the float bowls which had some goo in them, cause- bad gas,common reason nowadays-ethanol,I let it go too long.I now take care to make sure I do not buy more gas than I will use in 6-8 weeks(even though I do use Stabil ethanol treatment & Quikleen) and more important, run your motor out of gas after EVERY USE.I am trying out a disposable water absorber/filter that you hang in your portable fuel tank,looks like it has those dehumidifier crystals in it.It is made by Quicksilver/Mercury .The positive side of all this was an upgrade to a 40hp for $15,a new fuel tank which is now placed near the bow for better weight displacement so I could add a small kicker.For #2 , I went to boats.net after being refered to them from a boating forum.They have parts overview diagrams so you can actually see the exploded view of the motor.You just need your VIN # ,model & year.That is how I was able to add 10 more ponies to my motor.Wish you luck,Mike.

hewesfisher · Post by **hewesfisher** » Tue May 25, 2010 7:22 am

rseas, I'll have to agree with the consensus, it's probably fuel related especially if the tank has been sitting for awhile. One thing a seasoned Merc mechanic told me when we bought our first new Hewescraft back in '05 was to always run fuel stabilizer - year round. I did that with both motors on that boat (90hp carbed 2-stroke and 6hp 4-stroke) and never had problems. When we upgraded last year, the same mechanic told me the same thing even though we now have a fuel injected motor vs carbed, and he said it's more important with the DFI 2-stroke. Motors and shop rates are expensive, additives are cheap.

With the current poor fuel quality due to ethanol, it has become essential to use some kind of fuel stabilizer to keep fuel fresh and help prevent phase separation. I use Mercury brand Fuel System Treatment and Stabilizer as well as Mercury Quickleen every time I refill my tank. I know the marine StaBil is good, and have heard the same about Star*Tron. Since my motors are under warranty, I use Mercury products. I know Yamaha has a similar proprietary product but I don't know what it's called. I found a great price for the Merc products here. The 12oz bottle of stabilizer concentrate was $7.07/ea. Local prices are $15.99 plus tax. Even with shipping, I still saved almost $5 per bottle.

If you're running stabilized fuel, you don't need to run it out of gas because you want the stabilizer in the carb. If you don't stabilize your fuel, then running the carb dry is probably the right thing to do, but follow your particular motor manufacturer's recommendation. :thumright

Couple questions, how many hours on that Yammie? What is the ratio of trolling time to higher rpm running time? I typically run my 8hp kicker WOT for at least 5 - 10 minutes after a couple hour trolling session just to keep it well exercised and the plugs clear.

Post by **Bodofish** » Tue May 25, 2010 7:57 am

Clean all the filters, fuel pump and then make sure you aren't sucking any air at the various connecting places for the fuel line. I end up replacing my fuel line to the kicker about every two years for that very reason. Stabil, Stabil Stabil.

You can see if you 're running out of fuel by keeping a gentil squeeze on the fuel bulb. If that's the case check all the connections and the pump.

Trent Hale · Post by **Trent Hale** » Tue May 25, 2010 10:42 am

Try some seafoam this will clean the carbs and any water in the gas. It will also clean off the pistons and valves.

Coastfishin · Post by **Coastfishin** » Tue May 25, 2010 2:53 pm

My 15 hp Merc did the same thing, Ethanol in the gas turns to water! Dumped all the gas and refilled, runs great again

Post by **rseas** » Mon May 31, 2010 10:26 am

First, thank you to everybody that provided advice. My first step in resolving was to remove and clean the filter, there did not appear to be any sediment or water in the filter reservoir. Next I drained the various fuel lines and carburetor. After everything was cleaned out I drained all but 1 gallon of fuel from the tank and heavily dosed the remaining fuel with SeaFoam. I then started the motor and ran it in gear (in a garbage can of water) at about 2,000 rpm for 20 minutes and then shut it down for a while and let it set. After an hour or so I restarted the motor and ran it at about 1,800 rpm until it ran out of gas and you don’t want to know how long it took. I refilled the gas tank and added the appropriate amount of Stabil (Spelling? Or something like that.). So far so good, because of ongoing battery problems (well maybe not battery problems but a lack of funds for the purchase of a new one), I used the big motor for most of my trolling this weekend and the motor ran, idling for extended periods with out a hitch.

hewesfisher · Post by **hewesfisher** » Mon May 31, 2010 11:34 am

sgpwayne · Post by **sgpwayne** » Mon May 31, 2010 5:05 pm

I was reading the new issue of Bassmaster Magazine the other day and came across an advertisement about a product called Star Tron fuel additive. Went on the web site at www.startron.com and was impressed with the product. Has anybody at WALakes used this product or know some one who did. Thanks WAYNE

Post by **Amx** » Mon May 31, 2010 5:15 pm

local stores that carry it;

http://mystarbrite.com/startron/content/view/119

edit: well the link didn't come thru with the list, but there are a few - 25 or so - in the Lynnwood to Tacoma areas that carry it.

So put in your zip code and see what comes up.