Fuel issue with 2006 F115TXR

[itshamortime]

Please read entire story before offering advise.

I bought a used 2002 prokat 22 ft with 2006 twin Yamaha F115TXR in March of this year. Here is the story.

Original owner had a insurance claim on the boat in December of 2009 and his previous motors were replaced by insurance with these 2006 F115. They were new leftover engines. (warranty puched 12/09, I have the warranty cards.) When the motors were installed $5 in gas was put in each gas tank and motors were water tested. Fuel was not drained and boat set from 12/09 until 03/11 when I purchased it. That is the story on the boat now here is mine.

One motor runs 100% great so lets focus on the other. I replaced both batteries, oil, oil filters. The one motor initially would spit and sputter at anything over 1500 rpms. ZReplaced exterior 10 micron fuel water seperators. After that the engine would run up to 4500 prm's for about 1 minute then would cut back to 3800 rpm's. If you stay under 3800 rpm's for a few seconds you can get back up to 4500 rpm's for a minute and it would drop to 3800 again.

Took boat to authorised Yamaha dealer and had VST tank and filter cleaned (filter was not replaced, I should have ask.) Still same symtoms and was told I needed 2 injectors. Not one to skimp I went ahead and replaced a 4 injectors and small fuel filter under the engine cowling. Now the boat will run up to 5500 rpm's for about 3 minutes and the cut back to about 4200 rpm's. Once again if you stay under 4200 rpm's for a minute or 2 you can get back up to 5500 prm's for 2 or 3 minutes before it falls in RPM's again.

Obviously I am making progress and am almost there. What should be my next step. The only filter that has not been replaced is the inline right before the VST tank.

[itshamortime]

bump. Looking to go work on this on Saturday. Any ideas or directions to go in?

[Sparkieboat]

why have you not replaced the "only filter to not be changed" ?? seems like the right thing to do to me. you could have had those injectors cleaned, patterned and flow tested for about $25-50 each, that is what most people do. the yammy EFI motors have a lot of issues and seem to be very difficult to diagnose. Even some yamaha techs have trouble properly diagnosing. I post in a couple of different boards and have heard some real horror stories. The tech should have fixed it right, I assume you paid him a lot of money and still have a crappy running motor. defiantly replace the un-replaced filter. cleaning the vst screen/filter is fine, it does not need to be replaced usually.

[99yam40]

replacing things and hoping it fixes your problem is one way to go, but if you test with the proper equipment at the problem RPM to see what the problem is, it is a lot easier to fix/replace only what is causing the problem.

If you have restricted/plugged filters it will show up as a fuel pressure problem

[rodbolt17]

typical result from splatter gun techs.
why not simply clean the ENTIRE fuel system ONCE then go enjoy the rig??
your describing a typical loss of fuel.
easily tested.

[itshamortime]

injectors were replaced with flow tested cleaned, etc. injectors I picked up for $40 a piece, I now have a set of extra injectors I just got cleaned as well. I will be replacing the last filter this weekend. The boat is kept about an hour from my house so I am looking for more direction in case the problem still exist after I replace that one so I can try to accomplish more in one trip. I don't wan't to replace this filter and if the problem is still there be posting this same story on Monday as I won't be able to get back to the boat for 3 weekends after this one. My total service bill was $220. They only did the VST before I pulled the boat from there because they wanted $220 an injector and did not offer a cleaning service. Afterwards from other dealers I heard nothing but bad about this store. They were the closest 5 star store to my boat. When I picked up my boat wireing harness were left disconnected as well as throttle cables so won't be retuning there.

Back to the boat. What I plan to do is replace that last filter and run the thing off of an auxillary tank to make sure the problem is not in the gas tank.

Any "DIY" advise if the problem persist on an auxillary tank?

[itshamortime]

I know it is a fuel pressure problem just can't find where it is coming from. Due to the long amount of time it takes to hit the bogg is is not being replicated in a water test tank and the only yamaha shop on the water is the one that I had issues with.

[Sparkieboat]

did you test the other 3 injectors?? it is normal procedure to do all injectors if you do any. As rod mentioned..clean the entire fuel system, every filter and injector. Glad to hear you did not buy new injectors, that would have run up a huge bill. it looks like you have a good head and knew to not let the tech run up a huge bill, it is a shame but you have to really watch some of those guys. you should learn how to clean out your VST and filter yourself and do it yearly. also change every filter yearly, even if you did not use the boat much. If it were my boat I would change the filter you mentioned and send off the other 3 injectors to be cleaned and flow tested. you can also get a fuel pressure gauge and test fuel pressure while running to look for pressure loss at problem RPMs..if that is good and all 6 injectors have been flow tested good, then you will need to start looking at electronic side. for some reason the TPS seem to get out of adjustment and need adjustment/testing pretty regular. not sure why but they seem to be a common issue.

[itshamortime]

This motor only has 4 injectors, but yes all 4 were replaced will flow tested injectors. Some people are starting to think it might be a stoppage at the gas tank. fuel primer bulb does not collapse during this but becomes not 100% firm. It that an issue or should the primer bulb not lose any firmness?

This is my first boat with outboards so not familiar with primer bulbs.

[itshamortime]

I work at a car dealership but am not a mechanic. I am borrowing one from a tech here to take a fuel pressure guage with me this weekend. Do I just connect it to the fuel rail and drive around like that? Is there some way to connect it and have the upper cowling still in the motor? I live in Houston so this is on galveston bay with lately has been very choppy and would not feel comfortable driving around with cowling removed.

[Sparkieboat]

rgr the 4 injectors..I got this post mixed up with another v-6 post. you had only mentioned changing 3 of the injectors, I just wanted to make sure all injectors have been flow tested. find a smooth area to take off cowl and test run, there is a connection at the top of the fuel rail for the fuel pressure gauge, I think 35 psi is the minimum. check your manual to make sure. fuel is sucked into engine compartment so fuel bulb will get soft when running but should not collapse..if it collapses it should be replaced. make sure you have the right size fittings for the fuel gauge before going out..

[itshamortime]

I got the right fitting and the service manual.

[rodbolt17]

if the primer bulb collapses during running then there is a restriction between the bulb and the liquid level in the tank.
any decent dealership will have test wheel YB 1624.
that means you can spin the engine full load,full rpm on the trailer.
otherwise the hood is not secured and you do it zipping across the pond.
TPS is a rare failure.
blamed a lot but actual failure is rare.
I may have replaced 4 in the past 12 years.
however the F115 is incredibly simple to diagnose.
ya replace the injector filters at breakfast?

but if you reintroduce trsh into the injector filters at lunch ya get to clean them again at supper time.
thats why the entire fuel system must be cleaned all at the SAME time.

ya may need an alternator

[itshamortime]

What makes you think I need an alternator? Anyone know if that is a warranty item. So far nothing else has been.

[rodbolt17]

the altenator thing was a joke.
you dont need one.

you do need to monitor fuel rail pressure at the failure RPM and load.