question about yamaha motor stalling

tsport

Seaman Apprentice
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Apr 7, 2012
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i have a 2001 ox66 225 it was running perfect lets say yesterday. today started it and it seemed to smoke on first start up and run/idle a little ruff but didn't stall so i headed out figured it would clear up once it got to run I have to go about 1/4 mile of no wake before opening it up and it did it with no issues. then i went to 1/2 - 3/4 throttle she junped right up on plane all was good. then it was like someone pulled the throttle back to stop and the motor died i hit the key she sputtered then stalled I checked the priming bulb (never had to before) it was soft but pumped up. motor started i turned around tried to go again as soon as i was up on plane same thing. so i changed out priming bulb both fuel filters one after the tank and the one on the motor. but it still acts the same. so after doing some research the problems seems to be the low pressure fuel pumps. now i didn't do a pressure test on them but i can't think it could be anything else but i'm open for suggestions and i don't know of any better place to ask than here so what do you all think?
 

yamatech43

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Feb 9, 2011
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Re: question about yamaha motor stalling

There's a good reason nobody will address this thread....do you see it?
 

99yam40

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Re: question about yamaha motor stalling

Testing is always better that throwing parts at it and hoping
 

surrender

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Jan 25, 2009
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Re: question about yamaha motor stalling

With boat out of the water pump primer bulb and see if gas comes out prop hub area. If so one or more of your low pressure pumps is bad. Or you can unbolt LP pump one at a time and pump primer bulb. If fuel leaks out the back of the pump its bad. Dont bother with rebuild, new ones are about $40.
 

Capt Ken

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Jul 30, 2002
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2,270
Re: question about yamaha motor stalling

Being the low pressure pumps operate off of the intake pressure, how do you figure the fuel will leak out the exhaust when you pump the bulb? It would have to fill the intake, flow past the piston and out the exhaust.
 

tsport

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Apr 7, 2012
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Re: question about yamaha motor stalling

this is what i was asking for; a easy way to test / confirm my suspicions but i do have to agree with capt ken i think you would have alot more problems than a bad pump if fuel was coming out the hub by just pumping the bulb but hey i've seen/heard stranger things. Also i heard theres a screen in the vst tank that gets clogged is there any easy test check for it and is it expensive to fix
thanks again
 

Capt Ken

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Re: question about yamaha motor stalling

No way to check the VST filter without disassembling it. Not really hard to do other than you need to make sure the oring between the halves doesn't jump out and expand. Other than that, you can check your fuel pressure coming out of the VST tank and make sure it doesn't drop when the engine is under load.
 

tsport

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Apr 7, 2012
Messages
31
Re: question about yamaha motor stalling

update on motor after testing fuel pressure on vst it was 40 lbs i took the top low pressure pump off and disassembled. The rubber bladder had a hole in it the other 2 didn't have holes but they were pretty stretched out so i replaced all 3 and the motor runs great thanks again to all who replied
 
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