115 - 2007 four Stroke Yamaha

My 115 - 4 stroke was runing fine last Aug. it has been on the Barge setting in a boat house since that time, i changed my add on water filter, and put in fresh gas w/ heavy dose of Marine Sta-bal, when i crank it up it runs fine, i can take it out of gear and rev it up hold the tech at 4 gran, but take it out on the water and once i get to about 2000 rpm it bogs down, i called my Mechanic (who is a long way from me) he said first thing is to check the water pressure, i have none, but the little boy is peeing out the back, he thinks my water intake may be fouled from setting in the water all winter, my Question to You'll is do you know how to clean the water intake other than using a brush on the out side and clean it real good, i am think of taking the rig out of the water and the before i hook up a water hose to the clean out connection, pouring a cup or so of Bleach down the hose then connect it to the motor and run the bleach trough the system, once i do that i will put a treatment of sea foam in my tank and run the motor then let it set for a while incase my injectors or dirty, do any of you have any think that you can point me at to try and keep from having to drag this rig 50 miles tohave it looked at, Thanks for what ever you can do to help this Old Man

I have two f115 and this sounds exactly like the problem I had and it's probably a plugged VST filter. The way to test this is to hook up a fuel pressure gauge to the schrader valve on the fuel rail and get the boat out and see if the fuel pressure drops off when your power drops. The fuel pressure should be about 40 psi and should stay there. If it's 40 at idle and out of gear, but drops when under higher power the high pressure pump is being starved (most probably) due to the filter usually being plugged. The VST filter on the 115 is small and is a common culprit. I don't think your problem has anything to do with water if your pee stream is good. And although I haven't had it happen I've heard that if the motor gets hot there is an alarm you can't miss that goes off.

Unfortunately if it is your VST the intake manifold has to come off to get at it. But as I stated you need to check your fuel pressure when the problem occurs. I also had a performance problem due to a bad fuel pressure regulator, but if that is the problem your pressure will never get high enough even at idle. I bought a pressure gauge on line for about 50 bucks. Now days with ethanol in fuel, this filter plugging problem is becoming so common I think everyone should have one of the gauges.

If your pressure stays at 40 when your problem occurs you probably have some plugged injectors, but that usually has the engine running a bit rougher at lower rpms too. In my case the engine would idle perfectly. It's also possible your low pressure pump could be starving the VST so have some one pump the ball up to make sure fuel is flowing to the VST while the power loss is occuring.

I got tired of paying a mechanic everytime this happened and can change one out in a couple hours. But it is a bit involved as the intake manifold has to come off.

good luck

DWARD is absolutely right. This sounds like a fuel system problem. I have to service a 2004 model of this engine today. It has a bad regulator.

Hey Dockside..............how can that little regulator be worth over $200 bucks??? I also had to replace a high pressure pump on a f150 that they want $400 retail for??? I went to a auto parts store and a similar pump was just over a hundred but didn't have the same fittings as the Yamaha (and the pump on my f150 actually had a Mitsubishi insignia on it) I swear Yamaha has a license to steal on their parts :<(

Thanks<> dward<> & the rest of you for your help, i will order my self a gauge and check the psi out, may be a few day getting set up, but will reply to You'll when i have completed this test, Thanks again

Dward where is the best place to order one of these Fuel Rack Pressure Gages, i live in the Bon Docks so what ever i get i have to order it on line, <> next Queston, do i need a special fitting to connet to the rack,


Thanks LakeRat1

Just got home and called this site at the number listed above but it was too late. I did a parts search using the "search" feature above and didn't come across one, but I'd give these guys a call Monday morning and see if they have one first as we're using their site. Anyone else know if these guys have one?? I paid about $50 plus $10 shipping from simyamaha.com. The gauge just needs a schrader valve attachment. When you look at your fuel rail you'll see that it's basically the same thing as the valve stem on a tire and the attachment just screws onto it and depresses the pin in the middle.

You can also find them on ebay. I ordered mine when I ordered a bunch of OEM parts for fixing my f115s.

Thanks<> DWard <> for the heads up on where I might get one of these Pressure Gages, i will check with them Mon and go from there

LakeRat1

dward said:

Hey Dockside..............how can that little regulator be worth over $200 bucks??? I also had to replace a high pressure pump on a f150 that they want $400 retail for??? I went to a auto parts store and a similar pump was just over a hundred but didn't have the same fittings as the Yamaha (and the pump on my f150 actually had a Mitsubishi insignia on it) I swear Yamaha has a license to steal on their parts :<(

Click to expand...

The regulator is ridiculously expensive. I have a new one sitting in my service truck. They rust up terribly.

Thanks <> Dward & Dockside <> for your input on my problem, I will have to wait until next week for a Pressure Gage to come in, once i have checked my Fuel Pressure i plan to pull the Barge out of the Lake and service it all, It sure is nice for a Old Man ( 73 ) to have Guys like You'll to point me in the right direction, every thing out here has to happen in slow motion because there are no large part houses to get this stuff, once i think i know what i need i have to order and wait, but that is Life, Thanks again you Guys, i will reply back some time next week when i know a little more about what i have found

LakeRat1

One other thing to keep in mind is to make sure you have good clean fuel and tanks. I fixed the 115s I have down in Florida a few times before I realized I had bad fuel tanks and ended up having new tanks installed. If you have fuel filters plugging up......sometimes it's for a reason and you have to make sure you have good clean fuel and tanks. I don't know which fuel water separators you have, but the old standard was the quicksilver filters which were 25 micron. The inline filters on the Yamahas are 10 micron and I'd recommend making sure you put a 10 micron filter ahead of the engines. I actually went to 2 micron racor filters just to be sure.......but at least make sure you have a 10 micron filter ahead of the engine. Yamaha makes a 10 micron filter that screws on to most filter heads.

Thanks <> DWard <> I am using a NAPA Gold 3225 Fuel Water Separator Spin on and below that a inline throw away NAPA 3003 fuel filter all this before the Fuel get to the Motor, i Checked and the 3225 filter and it is 12 a Micron i will have to check and see if i can fine a smaller micron to fit the same base, i changed both these filters, I poured the Fuel out of the Old spin on into a clean white bucket to see if any water of trash came out, just clean fuel, I am waiting now to get a Fuel Pressure Gauge, so i can check the rack pressure, once i know that, i am going to pull the rig out of the water so i can do a full service on the motor, I will do a post on what I Find, You'll have been a great help, In my day I have worked on all kind of equipment plus when i was a Young man if i could not fix my old car I walked until i got it going, But this New Stuff is a lot different, It Sure helps to Have some one to point to the possible Problems

LakeRat1

If the fuel from your spin on filter was clean, chances are you don't have a dirty fuel problem. When I was having problems there was always a fair amount of junk that would pour out of the spin on. You can get the 10 micron Yamaha filter for about 20 bucks..although given you have clean fuel I don't think you have a dirty fuel supply problem and the filter you have is probably fine. .As I stated earlier, unfortunately the VST filter on the inlet side of the high pressure pump is very small. I have a f150 and the filter on it is much bigger. If you are going to service the engine yourself let me know I can share what I learned.

Basically a 3/8 drive with a 10,12&maybe a 13mm socket with a 6inch extension and a universal adapter.....along with a 10 and 12mm open/closed wrench will get it all done.

Thanks <> DWard <> once i know what the fuel pressure is, the barge is coming out of the water so i can get to everything & I will be the one doing the work under a BIG SHADE TREE, i have a full set of Tools, i will just need some pointers as to what all i need to do other that Changing the oil, change the Lower unit Oil, and service the Fuel system, I am thinking that even if my Rack Pressure shows good when the motor bogs down i might as well clean this VST Filter while it is out of the water, i know for sure it has never been cleaned, we bought this motor new when ever, i say it is a 07 but i might be a year older or a year newer, You will know what i mean when you get to my age, what i need to do is go down to the Boat House and get the numbers off the motor, then we will know for sure

Thanks Again LakeRat1

<> DWard<> I sure am Glad I have Not been Having Birthdays all these Years, I went down and Checked the Motor ITS a 05 motor, talk about time flying BY, the Tag says 6- 05 i cant get to the Left side to get the Ser. Number, i though i had put all that info. in my Owners Manual, but i guess i had another Senior Moment

Thanks LakeRat1

If anybody sees a rusty fuel pressure reg on an F115 check the seal on the cowling air duct. When they leak they drip inside on the regulator and other things.

PBRMAN,

On the two f115s I have the one that needed the regulator replaced had a rusty ugly regulator.....I'm trying to envision what leak you are talking about.......can you describe what you are mentioning a bit?? Is it a leak from the outside or inside??

On another regulator note I put a little system together to clean my injectors that I also used to check the regulator. I basically put together a quick connect to a compressor followed by a valve and then a air pressure regulating valve with a hose connecting to it that I would fill with sea foam and push through the injectors with a 9 volt actuator hooked up to the injectors. I worked great for the injectors but it also worked to check the regulator too as I believe the half inch hose that fit over the injector fit right over the regulator and with a little hose clamp holding it on I dialed the pressure gauge up to 40 psi and wellah...it opened and started hissing at 40 psi.

Obviously having a fuel pressure gauge that reads at 40 psi tells the same thing in a better way........but when I was fixing my f150 and things were all torn apart (the f150 regulator is under the intake manifold with the VST) it let me confirm the regulator was good. Had it been bad I would have had to put things back togther before I found out the regulator was bad and then have to tear it all apart again. In my case the high pressure pump had gone out so I wasn't able to run it with the fuel gauge ahead of time. On the f115 the regulator is outside and right on top of the fuel rail so wouldn't have been as important.

On the top of the cowl where the air comes in on many models of Yamaha motors is the air duct which is bolted in from inside. That air duct has a gasket or seal made from some sort of rubber which doesn't always stay sealed. Run a water hose in there with a slow stream and look at the leakage from inside. Some motors also have drain tubes which can become plugged. Unbolt the duct, clean it up well and reseal with marine silicone sealant. Yamaha has a recommended sealant. Kind of expensive though.

LakeRat1 Needs MORE HELP!!

Last week we (Being DWard and some othe fine Helpers) decided that i Needed to ck. the Fuel Pressure on my 115 - 4 Stroke, OK i have my Test Unit now, BUT the unit has a schrader connection for GM, MY schrader connection is smaller, its the same size as a car Valve stem, what type adapter do i need to ask for, is it called a mimi schrader or what, the kit came with all types of adapters for Automotive, there has to be and adapter to fit this small schrader connection, Just dont know what to ask for, Thanks for what ever help you'll can shead on my problem,
This Old MAN is still Digging!!

LakeRat1

I can't say I know what the exact schrader valve designation for the yamah outboards is. I got mine from a yamaha dealer that I mentioned above. You might have to call a dealer to find out.......or you might be able to size the cap that covers your valve to the right connection.