2016 F115 Stalling under load at power

[Wygantmb]

I'm at my wits end. I can't figure this out. The boat is less then one year old. Only have 27 hours on the engine. Yamaha F115. Ran perfect last year. Pulled it out of winter storage and now it won't run above 4500 rpm without stalling. I've drained the entire fuel system. Changed all the filters twice. Cleaned the vst. Changed the spark plugs there set at .040". Still no luck. I know it's under warranty but I'm worried if I take it in somewhere they'll have it most of the season. Any ideas would be great.

[pstephens46]

Can you check fuel pressure at the failure point? There is a fitting on the fuel rail to attach a gauge. Have you tried pumping the ball to keep it running at that rpm?

[rodbolt17]

quit
stop
just back away slowly.
use the Yamaha dealer locator.
find a dealership that employs a master tech.
take it in.
most likely it will be the VST filter clogged.

[Wygantmb]

I have pulled the vst apart and the filters both the one on the pump pick up and the inline filter are clear. With my work schedule getting the boat to a mechanic isn't an easy task since that all work bankers hours and I work an hour from home. Although I appreciate the feed back I am well aware that taking it to a shop would be a fix but it's not a good option for me. I'm looking for some helpful knowledge. I am a jet engine mechanic and have been for 18 years. I can turn a wrench. Unfortunately there are no manuals for a brand new engine. And I can't hook an obd2 reader to the boat. So if anyone has any real information please help.

[fairdeal]

well, you've already gotten advice from the most experienced person here that its likely fuel starvation from a specific cause - but there are several possible causes.

and you've gotten suggestions on how to simply and directly start diagnosing.

reprising -

get a 0-100 pressure gauge connected to the fuel rail - hopefully that model has a built-in Schraeder - otherwise you'll need to adapt something.

that will confirm - or eliminate - losing the ~45 psi that the injectors need

if you have the pressure at the injectors, its not a fuel supply problem
if you don't - then work backwards to find out why.

could be a restriction
could be an air leak on the suction side

use the priming bulb as suggested to see if its the VST running empty.

[rodbolt17]

could be most anything. you need the Yamaha adapter to access the fuel rail.
you need a bit of training on EFI single throttle body speed density open loop systems.
there are no sensor that will fail and shut off the engine.
there are a few relays and fuses that could.
that is why I say use the dealer locator,find a master tech.
that test is not a joke and unlike the old merc stuff you either know what you are doing or you simply fail the test.

I understand your a jet tech, great.
I am a Yamaha master tech.
over the years I have been certified for Volvo marine,mercruiser,mercury,suzuki tohatsu and some others.
I was a CIWS tech in the USN.
I programmed and set up CNC lathes and mills at GOEX for 6 yrs.
the only reason I will open the hood on my 2015 F150 is to add washer fluid.
the rest a trained tech gets.
kinda like inserting the klnife between the second and third rib.

[rodbolt17]

capt
there is nothing but washer fluid I know about my F150 or my wife 2016 explorer.
so I stay out from under the hood unless the washer bottle low lamp comes on.

I replace powerheads,timing belts and all kinds of stuff on Yamaha outboards and Volvo sterndrives.
I have no tooling nor training on an F150 so I take it to a place that employs Ford trained techs.

[boscoe99]

As a jet engine mechanic you know that trouble shooting has to be done. Not easy at times. Requires specialized test equipment at times. Will make you pull your hair out (mine is all but gone) at times.

Several simple tests can be done if one suspects that it is fuel system related. A lack of fuel that is. But some test equipment will be needed, same as on Rolls Royce Trent 1000.

A vacuum gauge can be plumbed into the fuel inlet supply line, to see if there is an excessive restriction to fuel flow that might cause the motor to be starved for fuel when it is at power and the fuel demand rate is high. You should not see more than about 4 ~ 5" Hg on the gauge if all is well. If you see too low of a value that could indicate a leak into the fuel system that results in a lack of fuel. The pump is drawing air and not fuel.

A fuel pressure gauge can be plumbed into the fuel output system to see in fuel pressure is being maintained at all RPM's. If the fuel pressure falls off at or about the time that the motor bogs down then that is indicative of a clogged VST filter, primary fuel filter, deficient fuel pump, etc. If the fuel pressure does not diminish and the engine loses power then that could be indicative of partially clogged fuel injector and/or FI filters.

An even easier test is for you or a buddy to mist gasoline into the air inlet box when the motor is starting to die. If the motor picks up and runs well that is indicative of something causing the motor to be starved for gasoline.

While not knowing what your problem is, know that fuel issues are the number 1 problem on Yamaha motors. More than likely on all other outboard motor brands as well. I would start with the fuel system and then go from there.

Good luck.

[Wygantmb]

I called two of the local Yamaha service places nearby. Of course no one can see the boat before June. However after reading a few of the responds which I do appreciate the fuel issue keeps coming up. After thinking about it. I had issues getting the tank to siphon at the engine without the gas cap open and the other day after pumping the primer ball what seemed like 100 times I opened the gas cap and could hear the air rushing back into the tank. From my under standing these tanks should vent at a very low neg pressure. I'm thinking my vent is bad. I'm about to hook the boat up and take a quick ride with the cap open. It's seems very logical to me. I'll let you all now what happens.

[TownsendsFJR1300]

capt
there is nothing but washer fluid I know about my F150 or my wife 2016 explorer.
so I stay out from under the hood unless the washer bottle low lamp comes on.
.

You can't do brakes(disc or drums), rebuild a caliber, oil changes, bleed brakes, etc?? Your kidding right?

[boscoe99]

Another quick test that I forget to mention is to plumb a three gallon or six gallon tank directly to the motor. If she then runs fine you know it is a boat side fuel related issue. If the problem is the same it is motor side related.

Damn the EPA and the updated style of fuel tank.

[rodbolt17]

can I do brakes,calipers and such?
I have since I was about 8 and I am 55 now.
was a time I could set up and grind crankshafts.
was a time I did seat and face grinding on heads.
was a time I could run a boring bar and a sunnen hone.
I don't anymore.
I do remember when a COATS 10/20 tire machine was high tech.
there is not much on my truck that a backyardigan can muck with anymore.
so I do what I do and take my truck to someone who does what they do.

[TownsendsFJR1300]

can I do brakes,calipers and such?
I have since I was about 8 and I am 55 now.
was a time I could set up and grind crankshafts.
was a time I did seat and face grinding on heads.
was a time I could run a boring bar and a sunnen hone.
I don't anymore.
I do remember when a COATS 10/20 tire machine was high tech.
there is not much on my truck that a backyardigan can muck with anymore.
so I do what I do and take my truck to someone who does what they do.

Quote: the rest a trained tech gets.

Well, gotta pick one. You can or can't, OR just don't want to (which is fine).

And I'm sorry but my boat/ bike, truck does NOT see a shop unless it's something I have no knowledge off or over my head.

As posted, I've had the TB's REPLACED (F150, same as yours) at a yamaha dealership(under warranty) for the low idle issue. Which YOU know is BS. Then they later literally tuned a nasty vib into the engine with a screw driver and left me hanging.

Certification doesn't necessarily mean squat...

Now why don't you change the original spark plugs in your Yamaha F150??
The manual calls for it YEARS ago... ?? How's that work??

What you posted for my engine issue breaking up at high RPM's (maybe 2 years ago) as VST fuel issues, was NOT the issue..

It was the spark plugs... Replaced em, fixed the issue... Now your a MT, but missed this one.. ???

[rodbolt17]

cause I do not wish to invest in tools specific to a 2016 explorer or a 2015 F1504x4.

can I do it? most likely.
why do it?
today I will play about the fish house and make about 3 large.
so why should I crawl under a truck and get nasty when I can spend a few hours doing what I know how AND have the tools and training for when I can simply pay someone that has the tools and training to fix my truck?
that and I wont own a truck out of warrenty.
coast me about 90 bucks to have the tires rotated and the engine oil and filters done.
when it gets down to needing a brake job it gets traded in.
the past 5 trucks typically went 60,000 miles on the same tires and brakes then got traded.
my generac home propane genset gets the same.
I use Hart services and 4 times a year it gets inspected/maintained.
in fact it just started and is self testing.
I repair to many broke motors due to technician/backyardigan induced failures.
typically they are not failures covered by warrenty.
my Yamaha F150 had the same annoying stall at light throttle opening.
took me about 4 hours to fix it back in 07.
since then I have done hundreds of them.
that was years before Yamaha changed the procedure.
I figured it out on my own.

I wont go to an ear surgeon with a broken arm .

why some supposed trained techs are not as good as others is a matter of personal pride I guess.

ohh, my Kv tester would have found that defective plug.

my vacuum mate aids me as well as my snap on fuel pressure tester and the YDS 2.23.

not only does a tech need tools and training they also need common sense and a firm grasp of how each subsystem acts with the rest.

I cant stand it when I draw a work order that simply says clean carbs or clean VST or change a water pump.
I wanna know why.
finding a good tech,doctor,lawyer or contractor is tricky at best I think.

[TownsendsFJR1300]

Well, we agree on somethings, you just plain ole don't want to do, etc.

I think most agree, you are one of the most knowledgeable folks here BUT, there are some/many "backyardians", that do have a grasp on different machines, basic's, etc.

I would trust them EASILY over certain "certified mechanic's" (as you posted, their hard to find, and yes they are).

Time is $ but an owner/backyardian isn't watching the clock as he tears into a WP on his OWN engine.

As a side note, I am VERY mechanically inclined (not so much with advanced electrical components), but choose NOT to do it for a living as I preferred it as a hobby (and still do). And have learned sooo much here as well (and still do).

IE, not all "barkyardian", non-certified, non-professional, etc folks are un-able to perform many of the tasks on their engine, (especially with the help here). You may want to lighten up on the many folks here that are NOT MT's, but are very capable...

Rant done..

Happy Easter everyone as well...