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New Yamaha F115 LB Not Peeing With Muffs Attached...

DiamondDave952

DiamondDave952

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I am perplexed as to why my new Yamaha F115 LB was not peeing when I attached the muffs to the water intake with the water turned on full blast (Full blast being what my well pump is able to deliver) so that I am able to winterize the motor. I was able to submerge the motor in a plastic garbage can to simulate the motor being in the lake since that was the last know condition that the motor worked properly. Doing so, I was able to get the motor to pee. See picture below. Feeling relieved that I my motor was working properly; I am now wondering why the motor did not pee with the muffs attached. For reference, water was spraying out between the muffs and motor housing as well as the other orfice on the motor. Is there a minimum water pressure that is needed? Anyone else experienced this before? Thanks for any insights you may have.
 

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Are the cups on your muffs round or rectangular? I had to buy a rectangular set of muffs when I first got my Yamaha about 4 years ago. They cover the intake ports completely.
 
sunedog said:
Are the cups on your muffs round or rectangular? I had to buy a rectangular set of muffs when I first got my Yamaha about 4 years ago. They cover the intake ports completely.
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They are round. That's a good point.
 
I used muffs for the first time today. Took about 5x longer for the boat to pee. Not as strong of a stream as when in the lake, but sufficient. Zoom into the pic and you will see my muffs are rectangular to match my intakes... plus, double sided water feed. Buy these and it will work.
7B5BC825-CDA4-4F6F-BD39-998163B08766.jpeg
 
AuthorizedUser said:
I used muffs for the first time today. Took about 5x longer for the boat to pee. Not as strong of a stream as when in the lake, but sufficient. Zoom into the pic and you will see my muffs are rectangular to match my intakes... plus, double sided water feed. Buy these and it will work.
Click to expand...

Weak pee stream, did you check it's prostate??

OP the pump/impeller probably isn't primed and can't get that lift - you may have to hold both muffs on tight and make sure water is forced up into the impeller to prime then pee.
 
Not uncommon at all on 150 & larger Yamahas to not pee, or barely pee when on muffs.
Does NOT always mean impeller is bad. Back it in the lake and often times it will pee just fine.
 
Bill N said:
Not uncommon at all on 150 & larger Yamahas to not pee, or barely pee when on muffs.
Does NOT always mean impeller is bad. Back it in the lake and often times it will pee just fine.
Click to expand...
That good to know it's not uncommon. I did the redneck thing and placed the lower unit in a garbage can full of water and she pissed like a race horse.
 
Had the same exact problem last fall and got an overheat alarm from insufficient cooling. I ended up taking tail unit off and rebuilt water pump totally in spring and saw melted components. I no longer trust the muffs as the pump sits just high enough that the muffs tend to leak just enough for pump to not be able to pick up prime. I tried both round and rectangle muffs on my Yamaha 150 at full water. It shouldn't have needed a pump rebuild at 79 hours. Make sure the trash can is plenty deep so level reaches pump. Also, mason bees and other insects tend to plug the pee hole with mud so now I put bright red tape (with a long doubled over obvious tail so I don't overlook it) over the pee hole when in storage. Plastic weedeater line is easy way to chase through the hole and inside hose to clear mud. Just takes a few minutes of dry start (no water) to damage pump as it is rubber impeller rubbing on stainless cup and needs the water lubrication.
 
In our marina we’ve had a few people with this problem. Our fix was prime first thru the upper flush hose connect and then immediately put on the muffs with full water pressure. It’s worked every time. If you don’t see water within 10 to 15 seconds, STOP the engine or risk water pump replacement.
 
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