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hoggs222

Yamaha 115 cuts out at low to idle.

22 posts in this topic

I have a 2001 Yamaha 115 2 stroke. 1st time out this year it worked fine, then started dying at almost idle. Next time out, it took around 10 minutes to start then ran fine at high speeds, but then started dying at low speed again.

I replaced the plugs around 2 years ago. Not sure if we've ever done the fuel filter. I picked up new plugs and a new fuel filter today.

Do you think these could be the issues?

Thanks,

Hoggs

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Dirty or plugged fuel filter will cause more of a problem at higher rpms than lower. Plugs are a good place to start. You may also have a little crud in one of the carbs that may have been there before, but now found its way into the idle circuit. Sea foam may help.

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I don't have any suggestions for you, but do tell us if you find the solution. My old Evinrude 90 Hp has exactly the same symptoms. It was runnine well all season so far until the last time I was out. I'm bringing fresh plugs (2 years old currently), will clean the fuel filter, and have seafom and some spray carb cleaner I will try. If that doesn't work I guess I will be towing her home.

I usually add some Seafom to most tanks of gas and only use non-oxy premo. I guess it would somewhat suprise me if it's the carbs, but it certainly could be. What concentration of Seafoam should I add to a 1 gallon tank? Any benefit to going a little stronger than what is recommended on the can? Any other suggestions out there?

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You may also have a little crud in one of the carbs that may have been there before, but now found its way into the idle circuit.

I agree with Bruce on this one... sure sounds like something floating around in the bowl of your carbs that gets into the low speed jet from time to time.

I'd try draining the bowls to see if that helps. It can't hurt.

One other thing to check - when it dies at idle, is the primer bulb sucked flat? It could be a weak fuel pump as well, not as likely in my opinion, but certainly a posibility.

Did you run fuel stabilizer through the motor this winter prior to putting it away?

marine_man

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What concentration of Seafoam should I add to a 1 gallon tank? Any benefit to going a little stronger than what is recommended on the can? Any other suggestions out there?

I'd go with the reccomended rate of seafoam.

marine_man

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I did run seafoam last winter. I'll check the plugs and fuel filter first.

I can usually get it to run fine in the driveway with the hose hooked up.

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I have that same motor. Two years ago the same type of symptoms in the early part of the season. I did not however have trouble starting it. Replaced plugs and the primer bulb. It was the primer bulb. Took two bulbs to get a good one from FF. Good Luck.

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Is the primer bulb (that's the ball to get the gas flowing right?) easy to replace? I'm not in front of it right now to look at it.

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Pretty easy. My engine has zip ties to remove and pull hoses off the barbs of the primer bulb, A utility knife may be needed if the hoses don't want to slide off. You probably will not miss the 1" of hose that will be removed. Note the size of the barbs for the correct size of a new bulb.

My situation was similar to yours, at open throttle it would run fine, but at slow speed it would be starved for fuel. The bulb had a small crack in it. When the engine was pulling hard the fuel would go. At slower RPM the fuel line lost its "prime" and would starve out.

I'm hoping this easy fix is the solution for you.

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Well, I tried new plugs and a fuel filter and it still did the same thing. I already bought em so I figured I'd try it anyway. I fired it up and the primer bulb was hard, but would lose pressure. If you kept pumping it, it would keep running.

I am on my way to FF or Sportsmans in the morning to get a new one. I'll let you know if that works.

Mine has a zip tie on one end and a metal clamp on the other end. Any idea if I could just use a zip tie on the end where the metal one was?

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So it dies if you don't keep pumping it?

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Yep, It dies if I don't pump the bulb OR kick it to a little higher rpm than idle.

Another note, there were around 15+ specs of sand sitting in the bottom casing of the fuel filter (not sure what it's called). I couldn't see any openings or clogging on the actual fuel filter.

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As for using zip tie to replace metal one I'd stick with the metal one. The side with the medal one gets more preasure delivered to it so it needs a stronger binding point.

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I've had 2 yamahas in 19 years . The best their is. Did you try putting fresh gas in the tank sometimes you can get water in the tank. I would get some heet red bottle you can put mulitple bottles in it won't hurt anything. I use seafoam alot I use way more than reconmmended. I don't change plugs very often. Clean them. Use after market hose clamps. The blub was a good idea But you should change the fuel line also.

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Charley, I was also thinking of changing the fuel line, since I had it out. Sorry forgot to mention that. Thanks for the reminder!

Hopefully I'll be able to hit the big pond in the morning.

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Ok, so does it die right away or after a couple moments?

If it dies right away, you more than likely do not have a fuel delivery problem. If the pump, line, connectors, etc, are the cause, it would still run on the gas in the float bowl until it runs out.

If it takes a a little while to die, then it could be fuel delivery.

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hoggs, What about the gas? Can you go fast at all?

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It runs just fine at higher rpms. I changed the bulb and it doesn't die anymore, but does seem to run a little rough now. A little sputter every once in awhile. Possibly carbs gummed up?

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Good news is this points more to a fuel delivery problem. I'd check the clamps/zip ties on the new bulb and make sure they are tight.

Are your RPMs varying at idle or steady? Idle should be around 600-700 RPMs, as a ballpark.

"Drive it like you stole it" as they say and let it have full throttle and gas a few times then check the fuel bowl again and see if any more gunk/sand came thru.

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Sounds to me like there might be junk in the carbs floating around, with a partially plugged low speed jet to me...

marine_man

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Again, not to detract from the original posters problem. Maybe mine is different or maybe it's the same, I dunno.

But my symptoms seem like the same ones (good performance at high RPM's, a definate miss at low RPM and dies at idle). I replaced the primer bulb, and added the recommended strong dose of Seafoam to the gas. I also used some Gum-out spray carb cleaner that I sprayed into the carbs while running. 3 out of the 4 carbs (on an 84 'Rude 90HP) would bog down while spraying in them. One of them did not. It seemed a little better after spraying the gum-out so I then replaced the spark plugs. If it is this jet, is that something that I could service separately, or is the whole carb recommended for changing?

It got progressively better throughout the weekend with the Seafoam in there. It was idling at the end of the weekend (still not quite right though). Do you all recommend continuing the Seafoam to see if I can get the gunk out or do I still need to rebuild the carbs? Sound like it's this low speed jet on one cylinder. Can I replace just the one jet, or is that only done by replacing the whole carb?

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Older V-4 OMCs only have 2 carburators. You must have been spraying into one side or the other of the top and bottom carburator.

Before going much further, check spark and compression. What did the plugs look like?

Spraying through them while running will not clean anything in the carburator except maybe the throat. Basically, what you were doing was adding fuel to the engine. when you spray and it bogs, typically it means there was already an adequate fuel flow and you just made it richer. If it picks up rpm, it means there isn't, you were acting as the carb. If it does nothing, no change in rpm, I start looking at other things such as the ignition-look for spark on all the cylinders.

The jets inside can be cleaned. If it turns out to be gunk in the carbs, I would suggest that you completely rebuild both carburators with kits. You run the risk of leaning out the engine with dirty carbs. Remember, the only lubrication the engine is getting is from the gas oil mix, and if you starve it of fuel for too long-SQUEEEK!!, time for engine rebuild.

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