Yamaha F115 Performance Issues

[jay00f4]

Re: Yamaha F115 Performance Issues

Alright I think I finally tackled it. I have had the boat out 4 times now with no problems. I will keep my fingers crossed but I think I got it.

 

[Peter632]

Re: Yamaha F115 Performance Issues

So, Captain-B, did you ever get your motor fixed? I am curious because I too have a Yamaha F115 and continue to have performance issues. It started last summer. I ended up taking it to two different dealers. The last one checked both the filters and then said the problem was with clogged and frozen fuel injectors. They cleaned up the injectors and the motor ran well running at about 5500 RPM. But, within a few weeks, it again began to slow down, even though I have been putting various stabilizers into the fuel.

I thought then that I would have it checked this summer and if I needed new fuel injectors, I would have them install them. I went to the dealer that fixed it last time, but they just cleared out the fuel water separator and that was in. Basically, the motor ran no better. Now a few weeks later I am at the point again where I can't get past 3500 RPM with really no power. So, I am off to dealer # 3. I will review the options listed in this thread, but this is getting ridiculous. I was wondering if it may be junk in the gas tank that keeps flowing into the system. Anyone have any thoughts on that?

Thanks,
Peter

 

[Casco Bay Outrage]

Re: Yamaha F115 Performance Issues

Peter-

By running stabilized fuel you most likely eliminated phase separation (from E-10 fuel) as a source.

While you don't say what make, model and year boat you have, there are two other possibilities:

- You have a hole or leak in your tank or one of the fittings.

- Your fuel fill, vent or gas line to the motor are degrading and the VST and injectors are getting clogged.

I have read of leaks in tanks where the hoses attach or where the fuel gauge remote sensor is mounted.

As for the hoses, they may appear to be in good shape, they degrade from the inside.

To eliminate the fuel tank and hoses, I strongly recommend you run the motor off a portable tank. You should change the water separator and possibly drain/clean the VST to purge any garbage from the system.

Does you boat have a deck cover that can be removed? If so I suggest you pull it if running off the portable tank eliminates the engine bogging.

 

[Peter632]

Re: Yamaha F115 Performance Issues

Thanks.

I have a 2005 Key West 186CC. So, I believe I can get to the gas tank reasonably easily. I think you are correct that something is contaminating the fuel. I am fairly handy, but how difficult is it to connect the motor to a separate tank? Also, finding some of those leaks you mentioned, I would have to leave that to a dealer.

One other comment I heard is that I may not be getting a good electrical charge. That the ground on the battery isn't solid or the terminals are not clean. It is a pretty new battery, but the cable connections are a little rusty. Do you think that could cause this type of problem?

Peter

 

[Casco Bay Outrage]

Re: Yamaha F115 Performance Issues

I know the following having replaced my fuel line:

The fuel line from the tank is without disconnect fittings. The line runs from the fuel filter, attached with a clamp ring on the port rear corner of the motor down along the bottom of the shroud, through the rigging grommet and to the tank.

You have two options:

A) Cut the existing line at a convenient location, capping off the old and then running a line using a hose mender to the above ground tank. Once you have the issue sorted, use the hose mender fitting to reattach the hose to your below deck tank, The hose mender looks like this

B) Pull off the existing hose and pull back to to the hull and cap it off. Run new hose from the filter back through the grommet and to the boat deck. You can purchase hose without fittings for as many feet as you need. Use a rope to approximate the path and then measure it.

While I don't think the battery cable is the source, clean all the connectors and posts. Make sure you have a good tight connection. I replaced the ring terminals with automotive style connectors to ensure a good connection to the battery posts.

Do the battery connection work BEFORE you work on the fuel line just in case I am wrong.

 

[Peter632]

Re: Yamaha F115 Performance Issues

That doesn't sound too bad. Once I have checked it with the external gas tank, would I need to replace the hoses or just keep the menders on?

I am going to work on it tomorrow morning and see what is up. I also think the VST might be clogged again. So, it would be a trip to yet another dealer. I saw on another forum a guy is cleaning and replacing the gas filters every 10 hours. It might just have to come down to that.

Peter

 

[Casco Bay Outrage]

Re: Yamaha F115 Performance Issues

While it appears daunting, having looked at the Service Manual, removing the intake manifold to get to the VST is pretty straight forward. My nephew who is very mechanically inclined, did it in 20 minutes.

Once off, the drain is right there. This fall I plan to do it myself to learn.

Any update Pete?

 

[Peter632]

Re: Yamaha F115 Performance Issues

Yep. I have the boat in a slip, so I went out there Wednesday moring to work on things. I cleaned and tightened down the battery connections. Then I checked the filters and everything looked clean. I ran it to see what was up. It was back to 4400RPM and 28 MPH. So, that is about where it was. But, I don't really think I had fixed it and I had taken a half day off from work, so I figured might as well take it to a dealer. I had one other annoying issue come up, the shifter went in reverse, but it would get stuck and couldn't get any more gas, not a good situation.

I went over everything with the mechanic and he thought things were strange and I shouldn't be having so many issues. It got to the point he was curious as to why it would work like this. He was the guy who said check the cables. Also, he noticed there was too much oil in the motor, not by my doing, so that could cause some overheating.

I took it in Wednesday and I am happy to see he got back to me and said it was all set. I was stunned that he did it so quickly. He checked the electrical, cleaned the fuel lines and the fuel/water separator. The boat worked OK, but he checked all the fuel injectors and it turns out one of them was bad. He replaced it and it ran well, 5600RPM, 36MPH. Where it should be.

I haven't picked it up yet, but I am "hoping" everything is all set. It just goes to show a good mechanic really makes a difference. It turns out that one of the fuel injectors had the wrong seal on it and spitting gas out under the cover. Also, the reason why the shifter didn't work right is a bolt was either loosened or left there by another deal and it got stuck in the shifter section.

I should know by Sunday if everything worked out all right and will let you know.

 

[Polar Rob]

Re: Yamaha F115 Performance Issues

Well i have been going through the same problem for over a year now with this 115 yamaha. keep paying for a temp fix from minmar marina in seaisle city nj. they told me i have a contaminated fuel tank and there is no way to clean it. After the injectors are cleaned it runs great for about 6 hours then loose rpms. when i took it apart myseldf i found little white chrystals in the vst and in the injectors. the boat has a plastic tank that is not supposed to be effected by ethanol. So i wonder is it an adverse effect from the fuel and ethanol the the goverment is hiding from us, my neighboe was having a similar problem and he started useing non ethanol fuel from Pa, and there went his problem. I have been useing 10 micron filters the whole time and not stopping this build up in the injector screens. I think is time that the goverment stops putting embargo laws on us the little guys and start making the airline industry more fuel efficent. How much emissions does a 747 burn on a two hour flight? yeat we get stuck in this situation when the corperate fat cats gain more weight.

 

[Casco Bay Outrage]

Re: Yamaha F115 Performance Issues

You don't say how old the boat is, fuel lines etc.

Once the VST, filters, injectors are clean, you are getting trash in the motor. It is either phase-separated fuel or degrading lines.

I would recommend:

- Drain the entire tank and discard.
- Replace the fuel fill and vent hoses, install new ethanol resistant gas line to the motor.
- Use a stabilizer such as Stabil or similar in every fill up.

I have run E-10 all year without any problems. You just need to keep the fuel treated.

 

[WadmalawJoe]

Re: Yamaha F115 Performance Issues

What ever happened to Captain B? I will have to be on the look out for him here in Charleston SC. I just got a 2004 F150 and I have been reading up on everyone's problems so I know what to look out for. This post got my attention because of it being a 4 stroke and so forth. It seems some guys put additives in every time and swear by them while others don't and don't have problems. makes me wonder if the additives are eating away at the hoses. Sounds like the best thing is to keep your filters changed and change the fuel hoses every couple years or so.

 

[Polar Rob]

Re: Yamaha F115 Performance Issues

Yes the fuel lines were replaced. I was informed that the white chrystals may be salt and oyr 4 slot vent may be letting salt water in the tank as we are under way so looking into that. Looked into the tank through the sending unit hole and it looks clean as a whistle. Going to syfen some off and see if there is any junk in that fuel also was recomended to change fuel stablizers, My question is if stay bol can be used in ethanol fuels why are they making one for ethanol fuel specific? Also found out that there is no regulation rite now on how much ethanol the fuel companies are putting into the fuel ( not being watchdoged) there has been as much as 30% found in some tanks. Briggs and straton makes a ethanol test kit for 10$ to tell you how muck is actually in a sample.again industry is sticking it to the masses so if u have had a 2 stroke blow up on you after the fuel switch that could very well be the cause.

 

[rodbolt]

Re: Yamaha F115 Performance Issues

those white crystals are most likly tank or draw tube particles.
if the clear poly tanks are exposed to sunlight they fail.
the new fuel blend reacts with sunligt and starts dissolving the tank,draw tube and sometimes the fuel level sender float.
this dissolved stuff will pass a fuel filter but tends to settle out in the VST and will attach itself to the pistons on EFI motors.
when the injector sprays the contaminated fuel the gas portion vapories as designed but the resin tends to start sticking to valve stems and piston skirts.