Outboard Engine Problem and Resolution

[Yam]

BACKGROUND: I have a 2013 Yamaha F150XA 4 stroke with 950 hours on it. I mostly use ethanol free gas but sometimes use regular gas(sometimes you have no choice), I always have used some type of additive such as Ring Free or Seafoam.

PROBLEM:  During my last trip on the Bay I decided to take a long trip in very big waves. My boat was jumping up and down for a good hour or so and after I finally found some calm water, my engine started acting up. It seemed as if one of my cylinders was not working. I was having a tough time getting on plane and once I did, my engine was only able to achieve 4500 rpms at WOT (Typical WOT was 5800 rpms). I checked my spark plugs and various other things, but basically, my motor needed some tender loving care.

RESEARCH: After investigating this problem thoroughly on the Internet, all signs were pointing to clogged VST filters. VST stands for Vapor Separation Tank and essentially is a small tank that gas is held in prior to being sucked into the fuel injectors. Inside this tank is a pump, a float, and a small screen filter. After gas leaves the VST, it then flows through another filter before it reaches the fuel injectors. On my Yamaha, this tank is inconveniently hidden behind the manifold. Apparently, Yamaha suggests to change these filters every 500 hours but this info is not in my owner's manual. This procedure could cost you $500+ if you take it to a "Yamaha Certified Mechanic!" Here is an excellent VST Filter Change LINK  I used to do it myself. 

INITIAL WORK:  Prior to changing my VST filters I went to Auto Zone and bought a fuel pressure gauge for $50. I then checked my fuel pressure by simply screwing in my new toy to the Schrader valve (tire stem) that is located on the fuel rail (See Link above for location of fuel rail).  I then took three measurements. 1. Key on. 2. Idle. 3. 1500 RPM. Of course, I hooked up my motor to water muffs before starting. All of my initial readings were close to 40 PSI which basically should have told me that I didn't have an issue with fuel pumps nor was my VST clogged. However, I was concerned that maybe I would get a pressure drop if I was on the water and opened her up. Thus I proceeded with changing the VST filters. 

I then followed the video shown above and after a couple of hours, was finished with the job. I then did another pressure check and did see a decent little jump in the pressure from 40 to 45. This made me feel like maybe I might have solved my issue. Thus I took my boat to the water. NO LUCK. The boat was still hard to get on plane and my WOT RPMs were way below normal.

RESOLUTION:  To make a very long and somewhat costly story short, the problem was determined to be the fuel injectors. I then foolishly purchased new fuel injectors and replaced the old ones and like magic, the boat ran better than I can remember. Quick response, fast to plane, and 5800 rpms WOT. However, alot of money could have been saved had I just simply had my injectors cleaned. There are several professional companies that will do this for you for 20-25 bucks per injector. However, for those of you who really like to do things yourself, I can vouch for the technique these guys use: Clean Your Own Fuel Injectors LINK.  I took my old injectors through this procedure, placed them back on my boat, and my boat ran as good as it did with the new injectors. Another helpful tip here is that you can simply check your injectors by testing the resistance on each of them using a simple voltmeter. If all of the readings are the same, then your injectors are good and simply need to be cleaned. Apparently, 99% of all fuel injector issues deal with clogging and not a bad injector.

LESSONS LEARNED: 

1. Cleaning your VST filters is a good idea but may not be all that necessary. Mine were not that bad after 950 hours and my fuel injectors still got clogged
2. Watch out for water in your gas tank. My water/gas separator filter looked like hell with only 20 hours on it. No doubt, I either got bad gas with water in it or that rough trip I discussed earlier shook up my tank enough to send any water in my tank to the fuel system. I drained my gas tank and found a half gallon of water in it.
3. If you suffer the same symptoms as I and your fuel pressure at the rail is good, then you probably have clogged fuel injectors. Either send them off to be cleaned or it do it yourself. Buying new injectors is most likely a costly mistake.
4. This is somewhat subjective. Fuel additive is BS. My bench testing suggests that Seafoam doesn't do anything unless you use it in very high concentrations. I can't imagine that a can of Seafoam or Ring Free does anything for your fuel system. It's your initial fuel filters (water/gas separator and main fuel filter) that do the work, and if they get blasted by bad gas, you are screwed.
5. When changing your main fuel filter, dump the gas out of the canister that houses it. This gas is often times really bad and will make its way into your fuel lines eventually. Thus dump it!
6. Another subjective finding. No matter which gas you use, it seems you are at risk. If you go with ethanol free, then you run the risk of getting old gas that has been sitting around in a pump and has a higher probability of having water in it. If you use ethanol gas, the chance of getting water is probably less but if this fuel sits in your tank for a week or so, the ethanol starts to separate from the gas and now acts as a cleaning agent that cleans out everything in your lines straight into your filters and maybe your injectors.
7. Your best defense against gas issues is to run your boat alot, check your main filters often, and be prepared to clean your injectors by yourself. I am convinced that every boat out there with 200+ hours on it would get a decent jump in performance if you just simply cleaned your injectors. I am also convinced we are all basically screwed when it comes to gas. Additionally, I'm convinced that fuel additives are nothing more than magic fairy dust. However, if your boat is sitting around without being ran for a while, fuel stabilizer is probably a good idea and I would be more comfortable with ethanol free gas in this situation. However, if you are going to the lake and plan to burn it up, I think ethanol gas is fine. 

Hopefully this info might help someone. 

Cheers,
Yam

[irons]

So... basically, just call yam and he can fix it for you.👍

[johnr]

Yam, I’m having similar issues out of my Etec. I’ve concluded it is the high pressure fuel pump located within the vst. Just waiting on parts...

This is a common problem. After a long sit, the fuel within the vst can separate, and the water settles to the bottom, corroding the fuel pump. I had used stabil in February, and parked it till August.

I’ve got a Yamaha too, so I’ll have to keep this in mind. I wonder if draining the vst would be a better solution for a long sit??

[Yam]

Sept 9, 2018 13:43:39 GMT -5 johnr said:

Yam, I’m having similar issues out of my Etec. I’ve concluded it is the high pressure fuel pump located within the vst. Just waiting on parts...

This is a common problem. After a long sit, the fuel within the vst can separate, and the water settles to the bottom, corroding the fuel pump. I had used stabil in February, and parked it till August.

I’ve got a Yamaha too, so I’ll have to keep this in mind. I wonder if draining the vst would be a better solution for a long sit??

Did you check fuel pressure? This will tell you a great deal of info.

Yes, draining the VST may be a good idea especially if you use ethanol gas. Non ethanol gas doesn't separate unless there is water present. Some think that draining the VST might allow condensation in. If this is the case, then maybe the best solution is to keep it full then after a long wait and prior to a trip, drain the system. Of course, with any draining, make sure you pump the primer bulb before starting. Also, I would dump the contents in the water/gas separator and the canister that holds your primary fuel filter.

[johnr]

I removed the pump and supplied it with and external 12v power supply. No signs of life.

I was concerned about the condensation in an empty vst tank too. Of course it lasted 10 years of fall and winter use only, with spring and summer sits, so maybe it was just time.

[steviejayvaughan]

Ran into a similar situation a few years ago on my F115 Yamaha. Engine would not hold wot and rpms slowly backed off the more you ran it. In my case the fuel pressure gauge showed 25psi and the pressure would move up and down. Upon tear down I found black particles in the fuel rail. The high pressure fuel pump in the vst tank had come apart and this black stuff was the pump destroying itself. Of course since my motor didnt have the filter between the pump and injectors I sent the injectors out and had them cleaned for a total cost of $80. The vst tank itself was clean except for the black particles.

I also invested in the Yamaha software and cable for my outboard. I think it was $50 on ebay and will read coolant temperature, tps voltage and 20 or so other inputs to the ecm for diagnosis.

[Yam]

Sept 9, 2018 14:13:28 GMT -5 johnr said:

I removed the pump and supplied it with and external 12v power supply. No signs of life.

I was concerned about the condensation in an empty vst tank too. Of course it lasted 10 years of fall and winter use only, with spring and summer sits, so maybe it was just time.

That's how I would view it. Just replace it and keep doing what you have always done. My Vst pump sits pretty high in my tank. Thus, if separation occurs, the water would be at the bottom and not touching anything important. Frankly, I would rather this happen versus an empty tank with condensation.

My plan is after longer sits (> month), I will dump the fuel filter canister first. If it is separated, then I will drain the vst and check it out.

[Yam]

Sept 9, 2018 14:20:43 GMT -5 steviejayvaughan said:

Ran into a similar situation a few years ago on my F115 Yamaha. Engine would not hold wot and rpms slowly backed off the more you ran it. In my case the fuel pressure gauge showed 25psi and the pressure would move up and down. Upon tear down I found black particles in the fuel rail. The high pressure fuel pump in the vst tank had come apart and this black stuff was the pump destroying itself. Of course since my motor didnt have the filter between the pump and injectors I sent the injectors out and had them cleaned for a total cost of $80. The vst tank itself was clean except for the black particles.

I also invested in the Yamaha software and cable for my outboard. I think it was $50 on ebay and will read coolant temperature, tps voltage and 20 or so other inputs to the ecm for diagnosis.

I had those black particles throughout my system from water/ gas separator to the vst. They look like pepper. I have heard so many theories what these are. I was fine thinking they were as a result of the ethanol cleaning your lines and would rather not believe they are pump internals.

[steviejayvaughan]

Sept 9, 2018 14:32:13 GMT -5 Yam said:

Sept 9, 2018 14:20:43 GMT -5 steviejayvaughan said:

Ran into a similar situation a few years ago on my F115 Yamaha. Engine would not hold wot and rpms slowly backed off the more you ran it. In my case the fuel pressure gauge showed 25psi and the pressure would move up and down. Upon tear down I found black particles in the fuel rail. The high pressure fuel pump in the vst tank had come apart and this black stuff was the pump destroying itself. Of course since my motor didnt have the filter between the pump and injectors I sent the injectors out and had them cleaned for a total cost of $80. The vst tank itself was clean except for the black particles.

I also invested in the Yamaha software and cable for my outboard. I think it was $50 on ebay and will read coolant temperature, tps voltage and 20 or so other inputs to the ecm for diagnosis.

I had those black particles throughout my system from water/ gas separator to the vst. They look like pepper. I have heard so many theories what these are. I was fine thinking they were as a result of the ethanol cleaning your lines and would rather not believe they are pump internals.

I also thought the same but there is a 10 micron fuel filter on my outboard before the fuel enters the vst tank and there is no way that black stuff made it past that filter. I hope this isnt the case for your motor only time will tell.

Although I agree with the manual clean of the injectors as a diagnostic tool I would not leave them in my outboard. A good ultrasonic cleaner that charges $25 an injector will check for injector imbalance. They will cycle the injector up to 6k rpm and match all the injectors. My F115 is a 4 cylinder and 1 injector was over 5% off at wot. I didnt notice any performance issues but on a $10k outboard I’ll pay the $25 an injector to not melt a piston years down the road from running too lean.

[Yam]

Sept 9, 2018 20:49:57 GMT -5 steviejayvaughan said:

Sept 9, 2018 14:32:13 GMT -5 Yam said:

I had those black particles throughout my system from water/ gas separator to the vst. They look like pepper. I have heard so many theories what these are. I was fine thinking they were as a result of the ethanol cleaning your lines and would rather not believe they are pump internals.

I also thought the same but there is a 10 micron fuel filter on my outboard before the fuel enters the vst tank and there is no way that black stuff made it past that filter. I hope this isnt the case for your motor only time will tell.

Although I agree with the manual clean of the injectors as a diagnostic tool I would not leave them in my outboard. A good ultrasonic cleaner that charges $25 an injector will check for injector imbalance. They will cycle the injector up to 6k rpm and match all the injectors. My F115 is a 4 cylinder and 1 injector was over 5% off at wot. I didnt notice any performance issues but on a $10k outboard I’ll pay the $25 an injector to not melt a piston years down the road from running too lean.

I agree that sending them in is a good idea. And that cleaning them yourself should be more viewed as a diagnostic tool that quickly tells you if they are clogged.

I sent my spares in after cleaning them myself for kicks. The shop told me that they were already in good shape. This alone is worth the 85 bucks I paid to have them professionally cleaned. And I would guess that many folks wouldn't want to put all the time I did into making my redneck cleaning station. Secondly, I'm not sure if keeping a constant voltage on them like I did will end up frying the injectors in the long run.

Btw, how do you like your diagnostic tool? Has it provided any value to you yet? How exactly does it work and what exactly does it tell you? I'm interested in getting one now that I'm a "yamaha certified apprentice!"

[steviejayvaughan]

Sept 10, 2018 4:35:40 GMT -5 Yam said:

Sept 9, 2018 20:49:57 GMT -5 steviejayvaughan said:

I also thought the same but there is a 10 micron fuel filter on my outboard before the fuel enters the vst tank and there is no way that black stuff made it past that filter. I hope this isnt the case for your motor only time will tell.

Although I agree with the manual clean of the injectors as a diagnostic tool I would not leave them in my outboard. A good ultrasonic cleaner that charges $25 an injector will check for injector imbalance. They will cycle the injector up to 6k rpm and match all the injectors. My F115 is a 4 cylinder and 1 injector was over 5% off at wot. I didnt notice any performance issues but on a $10k outboard I’ll pay the $25 an injector to not melt a piston years down the road from running too lean.

I agree that sending them in is a good idea. And that cleaning them yourself should be more viewed as a diagnostic tool that quickly tells you if they are clogged.

I sent my spares in after cleaning them myself for kicks. The shop told me that they were already in good shape. This alone is worth the 85 bucks I paid to have them professionally cleaned. And I would guess that many folks wouldn't want to put all the time I did into making my redneck cleaning station. Secondly, I'm not sure if keeping a constant voltage on them like I did will end up frying the injectors in the long run.

Btw, how do you like your diagnostic tool? Has it provided any value to you yet? How exactly does it work and what exactly does it tell you? I'm interested in getting one now that I'm a "yamaha certified apprentice!"

The ydis software I bought is pretty basic compared to scan tool software for car manufacturers. My F115 is a ‘04 model so things may be different when they did a redesign. A couple years after the high pressure pump almost left me stranded it developed a idle problem and would sometimes stall when pulling the stick back. The scan tool came with a cd and cable that hooked to the outboard diagnostic port. I found the throttle position sensor voltage was out of spec and was able to adjust that using the scan tool and a voltmeter. It was worth the $50 alone for me to do that. It could also be used to test for stuck open thermostat, issues with the baro sensor etc.

I’m not sure if you can get one for the ‘13 models or not. These outboards are pretty easy to work on in my opinion. You can find service manuals online for pretty much all of them. Timing belt changes are done in 15 mins. with a good flywheel puller. All other maintenance is pretty easy as well. I also agree with your opinion on fuel additives. As long as you aren’t letting it sit everything you need additive wise to clean the valves and internal components is already in the fuel you’re buying. I think its kind of like the old “you need to change your oil every 3months or 3k miles.”

[primetime]

On my vst, there is a sensor that will beep 4 times if water is present. I can drain the tank when the alarm sounds and/or during maintenance.

[Yam]

Sept 9, 2018 14:20:43 GMT -5 steviejayvaughan said:

Ran into a similar situation a few years ago on my F115 Yamaha. Engine would not hold wot and rpms slowly backed off the more you ran it. In my case the fuel pressure gauge showed 25psi and the pressure would move up and down. Upon tear down I found black particles in the fuel rail. The high pressure fuel pump in the vst tank had come apart and this black stuff was the pump destroying itself. Of course since my motor didnt have the filter between the pump and injectors I sent the injectors out and had them cleaned for a total cost of $80. The vst tank itself was clean except for the black particles.

I also invested in the Yamaha software and cable for my outboard. I think it was $50 on ebay and will read coolant temperature, tps voltage and 20 or so other inputs to the ecm for diagnosis.

Well interestingly enough, my fuel injectors clogged up after 20 hours. And once again, the black particles were the culprit. And guess what, these black particles stuck to a magnet! I then carefully inspected where they were in the system. There was some debris in the water separator but it didn't stick to a magnet. Additionally, the main fuel filter was clean. The only metal shavings I could find were in the vst and these were big enough to see. What I couldn't see without really looking hard was the very fine particles that were in the fuel rail and in the injectors.

So... It seems to me that black metal particles in your vst means it is time for a new pump. From running this past Andy at Sim Yamaha, he 100 percent agrees.

Bottom Line.... I am literally in your same boat!

Finally, with this new information, I am thinking it absolutely necessary to either buy ethanol free gas or drain your vst if you plan to leave your boat sitting for longer than 30 days.

[Yam]

Update: After installing a new High Pressure Pump a year ago, my boat has been running like a champ. Many thanks to StevieJay for leading me down the right road.

Quick Summary. If your boat is losing rpms at WOT (in my case 5800 down to 4000), you might have a clogged injector. Most likely, a clogged injector is caused by some other issue. In my case, after COMPLETELY draining the VST, I found black particles in the solution. These back particles were metal because they stuck to a magnet. Even though my VST has filters before and after it, these metal particles were still able to get into my fuel rail and clog my injectors. More importantly, these black particles indicate that your High Pressure Fuel Pump is going bad. The best solution is to replace the pump ($300 bucks OEM or $50 aftermarket) and get your injectors cleaned professionally ($100). You should also clean the fuel rail. If you take this to a mechanic, you could be looking at multiple visits and a bill well over 2k.

[Yam]

Oct 11, 2018 20:23:21 GMT -5 primetime said:

On my vst, there is a sensor that will beep 4 times if water is present. I can drain the tank when the alarm sounds and/or during maintenance.

Primetime, on my boat, my water sensor is attached to the small plastic cup that houses the main fuel filter. I wonder if this is the same on your boat? My VST is not visible unless you remove the exhaust manifold. My VST is a metal tank.