# Yamaha 90 2-Stroke Bogs Down



## camarox00 (Oct 5, 2017)

Hey Guys,

I have a 2006 Baycraft 175 w/ a 2005 (I think I am remembering correctly) Yamaha 90 2-stoke. I bought this boat last winter with a ETEC 90 on it and replaced it with the Yamaha. The entire boat was a rats nest and had to be rewired and basically everything besides the motor and trolling motor is new.

Anyways, the issue I am having is that as I am running or just idling the motor will sound like its bogging down and will shut off. My guess is it was getting air in the fuel or loosing fuel pressure, if that is the right terminology. If I reach back is squeeze the primer bulb the motor goes from bogging down to working strong again. If it cuts out then I have to squeeze the primer bulb and then turn the motor on and I'm good. 

So what I have done so far is:

Replace the entire fuel line
Replace the fuel water seperator
Replace the quick connect - thing that attaches the fuel line to the motor
Replaced the fuel filter O-ring
Replaced the primer bulb
Replaced the fuel pump
Tightened down all claps on the fuel line and everywhere else
Drained old ethanol fuel and added non ethanol

After doing all that it went from constantly bogging down to maybe 2-4 times in a 7 hour trip. I can't really thing of anything else unless you think it may be the quick connect from the fuel line to the motor.

Any suggestions? Or anyone else have this problem where they were able to ID the issue and fix it? Maybe the carb needs cleaning? Could it be crap in the fuel tank?

I've only been boating for under a year and I have learned alot but if I could solve this problem that would be great!

Any help is much appreciated! Thank you and sorry for the long post!


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## MariettaMike (Jun 14, 2012)

Drain your carb float bowls onto a white paper towel and check for debris.

Run your carb needle valves in and back out counting the turns. I think it’s 3-1/2.
Clean carbs if it comes back.


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## SomaliPirate (Feb 5, 2016)

I had a similar problem with mine once and it turned out to be the little check valve deal at the fuel tank where the line goes into it. I forgot what it's called. Also, as previously stated, check those carbs. Yamaha carbs are notorious for having lots of tiny passages and clogging with debris easily.


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## Guest (Jun 22, 2018)

SomaliPirate said:


> I had a similar problem with mine once and it turned out to be the little check valve deal at the fuel tank where the line goes into it. I forgot what it's called. Also, as previously stated, check those carbs. Yamaha carbs are notorious for having lots of tiny passages and clogging with debris easily.


The little check valve thing is called an anti siphon valve. Good advice so far! Also, check the draw straw in the tank. You can check for air entering the system by simply placing a piece of clear hose in line and watch for bubbles as you run the boat. I am betting MariettaMike is right and you have some trash floating around in the carbs.


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## JMZ400 (Aug 30, 2015)

My only advice is to solve this issue before you run a cylinder lean and ruin the motor. Don't mean to sound dramatic but been there done that.


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## ek02 (May 8, 2012)

The adjustment on the 2005 Yamaha 90 2 stroke needle valves is 1 1/4 to 1 1/2 turns out from fully seated. When mine starts sneezing at idle I take the needles out one at a time a squirt some carb cleaner in the passages and blow them out. Another problem with the Yamaha carbs is if they sit for a long time, the floats drop and the needle valves stick in the closed position. They are a tight fit and any stale fuel will make them stick. Cleaning the carbs with carb cleaner and blowing them out with compressed air will fix that problem. Mine stuck after sitting for 6 months after Hurricane Wilma. I use Stabil now and have not had a stale fuel issue since.


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## camarox00 (Oct 5, 2017)

Thanks for all the great advice! Will be checking all of these things to include the carbs. Motor did sit for a couple years after it was burned dry so no fuel sat in her. I will definitely follow back up here as soon as I have either gone through these things with no success or have the issue is resolved to let everyone know what it was.

Thanks again!


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## lemaymiami (Feb 9, 2007)

Something to remember.... Pros working on outboards when there's the slightest suspicion of a fuel problem (before the fuel hits the motor) will take a portable tank of known quality and run the motor with it by-passing tank, fuel lines, and filters. If the problem persists -then it's not your fuel system - and something with the motor...

Above advice about your carbs is probably right on - but... I'd only want a Yammie pro working on my carbs - too many opportunities for a DIY fix to overlook the real problem or not re- set things properly.

I'll be hanging out and listening to whatever you come up with - good luck!


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## camarox00 (Oct 5, 2017)

lemaymiami said:


> Something to remember.... Pros working on outboards when there's the slightest suspicion of a fuel problem (before the fuel hits the motor) will take a portable tank of known quality and run the motor with it by-passing tank, fuel lines, and filters. If the problem persists -then it's not your fuel system - and something with the motor...
> 
> Above advice about your carbs is probably right on - but... I'd only want a Yammie pro working on my carbs - too many opportunities for a DIY fix to overlook the real problem or not re- set things properly.
> 
> I'll be hanging out and listening to whatever you come up with - good luck!


Thanks for the response! I have a friend who is a mechanic and he actually just told me to do this exact thing. To isolate the problem before replacing and cleaning and putting hours into something that may not be the problem. If it aint broke don't fix it kinda deal.

He is going to hook me up with a portable tank and see if the issue persists before doing anything else. That way at least I know where to start at this point. And yeah, he told me to not clean the carbs by myself as I am not the most mechanically inclined guy and very new to working on boats....will probably make more problems then fix. 

As soon as I get some time I will do this and then update the thread until the issue has been resolved.

Thanks!


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## Vertigo (Jun 3, 2012)

It's the anti-siphon valve at the tank. Been there, had the exact same problem. If you're in a hurry for a fix, you can remove the valve put it in a vise and use a hammer and screw driver to knock out the spring and ball. Put the valve back and go fishing.


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## camarox00 (Oct 5, 2017)

Thanks for the replies y'all! I replaced the anti-siphon valve and hoping to test her out this weekend. Will keep you posted!


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## jimsmicro (Oct 29, 2013)

Clean the carbs, you're throwing parts at this thing left and right when that's the obvious issue to me and costs virtually nothing to do.


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