Hey ivar and rodbolt

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redbull660

Petty Officer 3rd Class
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Jul 25, 2004
Messages
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Can either one of you or both tell me where the fuel filters are on my 2003 yamaha 115 hp 4 stroke. I have taken off the clear looking fuel filter on the engine and have emptied that out, It was clean. I have taken out all four fuel injectors and have sprayed them out with air. Is this all I have to do as far as filters go or is there any other ones that I may be missing. Thanks guys. :confused:
 
JB

JB

Honorary Moderator Emeritus
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45,907
Re: Hey ivar and rodbolt

Have you considered looking in the Manual, Cory?
 
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redbull660

Petty Officer 3rd Class
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Jul 25, 2004
Messages
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Re: Hey ivar and rodbolt

I dont have a manual yet, I ordered one but it wont be here by this weekend and I wanted to use my boat. I will keep looking, sorry to bother you guys. Also have a good labor day weekend and stay safe. Thanks
 
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rodbolt

Supreme Mariner
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Sep 1, 2003
Messages
20,066
Re: Hey ivar and rodbolt

no bother. the VST has a filter inside it on the high pressure pump. the intake manifold has to be removed to acces it. what are your symptoms again ?
 
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redbull660

Petty Officer 3rd Class
Joined
Jul 25, 2004
Messages
76
Re: Hey ivar and rodbolt

It usually runs at 5000 rpm with a stainless steel impeller (jet drive). I took it out sunday and only could get 4800 rpm out of it. It progressivly got worse clear down to only 3800 rpm. the engine does not miss, it seems to be running on all cylinders.I will try to find the filter on the vst if you can tell me where it is. I am a real good mechanic just dont know much about this engine. thanks
 
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bigbrownbuku

Master Chief Petty Officer
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Sep 17, 2004
Messages
885
Re: Hey ivar and rodbolt

first check you havent picked up any rope or other crap causing drag on your impellor/driveshaft.<br /><br />the vst is behind the intake manifold. check carefully your entire fuel system for bad hose/cracks/leaks.
 
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rodbolt

Supreme Mariner
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Sep 1, 2003
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20,066
Re: Hey ivar and rodbolt

the VST is the tank looking thing behind the intake manifold. you can test high pressure fuel with an automotive fuel rail pressure gauge. its a standard schrader valve. you have to remove and open up the VST to find the filter. its on the bottom of the high pressure fuel pump. you will need an intake gasket and a VST gasket. if not damaged the filter is cleanable. your really going to need to wait for your manual. there are some other tests you may need to run. the manual put out by mercury marine is superior the the yamaha one but be careful both have some flaws.
 
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redbull660

Petty Officer 3rd Class
Joined
Jul 25, 2004
Messages
76
Re: Hey ivar and rodbolt

It works great now. I cleaned out the filter/water separator and then took off the injectors and sprayed them out. I did not touch the vst (my manual is not here yet). I put it in the river and it runs great. thanks guys for the help.
 
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