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Yamaha 115 - 4 stroke 2006 Fuel Trouble/ VST Filter

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LakeRat1

Member
Hi You'll LakeRat1 here, back about 2 or so weeks ago i was in contact with some of you about my fuel trouble. we decided it must be the VST filter, & i was supose to check my fuel pressure, that never happen, i can not fine a adapter to go from the Standard Schrader conection on my fule Pressure test unit to the small Schrader conection on the Yamaha fuel rail,( do any of you know where i can buy such and Adapter?) so i have pulled the Barge out off the water, now i am looking for the VST filter, i under stand it is behind the Intake on the left side of the motor, what i see is the fuel line coming into the small fuel Filter, then to what i think is the low pressure fuel pump on the back of the Motor, then from there it is a short line to some sort of inline type thing about 2 to 2 1/2 in. long with a hose clamp on both ends this is right behind the intake near the rear left side of the motor, then from there the hose goes on to where i dont know behind the intake, am i on the right Track, i would love to look at a parts manual or something that showes what i am looking for, Thanks for any help You'll can give this Old Man.

DWard are you around?

LakeRat1
 
If you do this job to clean your VST it will be most important to clean the fuel rail and injectors before you reassemble.

If you don't clean these you will have the same problem.
 
Thanks for the Replys, First let me correct my Info>< on the Yamaha 115, Its Not a 2006<> Its a 2005 Yamaha 6-05 and on the Left side Data Plate it Has (Top Line ) Yamaha F - 115 T L R (then the Second Line Has) 68 V - L - 1050913 -K

Docksidemarineservices<> when you speak of cleaning the Injectors & Fuel Rail, do you mean having them sent off and have a fuel flow test and cleaning job done, or soaking then in something like Sea Foam or something like this and then blowing the out? Or is there some other a way i can clean them here with out any special equipment?
 
When you pull the intake to clean the vst it would be a good idea to send the injectors out for cleaning. Make sure you clean the fuel rail too or you will be back where you started from.

I am currently doing the same service on a 2004 F115.
 
You're on the right track. The pump on the back is a diaphram pump that feeds the VST. The bowl and filter on the back has a red disc inside to tell you if there is water in the gas....the red disc will rise up in water and stay at the bottom if no water there. The cartridge filter is to filter between the mechanical pump and VST.

To replace the VST I first removed the plastic air intake from the intake manifold. There are about 2 or 3 bolts that go through the manifold into the block, and about 6 that bolt to the intake itself. You'll need a ujoint and extension to get the bottom bolt. The intake itself has a couple bolts on the intake side and about 5 that bolt it to the block. There are 3 bolts that hold the VST to the intake (mine had yellow paint on them) and I'd wait unitl the intake is loose and leaning out before removing those. There is a metal gasket between the intake and block that you need to remove and keep track of which end is up and down as the bolts don't line up if it's not on correctly.

Once the intake is leaning out, there is a fuel line on the bottom of the VST that is a return from the fuel regulator and the intake fuel line that I removed from the VST. I left the high pressure line to the fuel rail on the VST and removed it from the bottom of the fuel rail. There are also a few vacuum lines that need to be removed from the VST. You'll need a 3/8 drive 10mm, 12mm abd 13mm socket with a 6"extension and a ujoint as the bottom bolt on the plastic intake is down in there. Once the VST is out a phillips screw driver gets the bowl off and then you'll see the VST filter which you replace.

As for the injectors they are a lot easier to get to and may or may not be plugged. It's about $20-$25 each to have them serviced........you decide whether you want to service them now or later. The fuel pressure reading would help you in figuring whether they are plugged up or not. I'd guess that once the VST filter is clean and changed things will run a lot better. I did a lot of research and figured out how to clean my own injectors, but it takes an ultra sonic cleaner and an aparatus to push cleaning fluid through the injectors. I did this because the boat is in Florida and I was on a tight schedule.......if I had the boat around I probably would have had the injectors cleaned by someone like injectorman.com or others I heard about on this site.

Below is a link to a picture of before and after intake is removed. When I changed mine I didn't take the intake completely off, I leaned it out. I also googled "change yamaha f115 vst" and found a bunch of information that helped, and you'll probably find something that I didn't see.

http://www.thehulltruth.com/boating-forum/297623-yamaha-f115-vst-filter-change-w-question.html
 
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