Yamaha 115 slow on 19’

I have a new to me 2002 Yamaha 115 (295 hours) 4 stroke I just had the VST replaced and all kinds o junk was in the reservoir and the filter was pretty plugged. The engine runs strong but just not seem to be moving the 19’ deck boat fast - and on a calm lake. I replaced the fuel line and bulb, no water in the separator. New gas filter.

Here is maybe the problem? The gas in it was stabilized end of 2017, it was not used in 2018 and stabilized again. When I started it up - it started on second turn. That was before the new fuel line/bulb and VST. Aren’t there injectors that can get plugged due to ethanol and bad gas?

Im not sure if the plugs were ever replaced. Engine seems to run strong and not skip. The guy at the marina that replaced the VST took it out on a river and he said it seemed underpowered- but that was it.

Thanks!

Yes, you should remove the injectors and send them in to be cleaned professionally. Those can definitely get gummed up and clogged due to old fuel.

The plugs might be just fine, but they're so cheap, you might as well replace them.

If you find the same problem after that, then consider a different size/pitch prop. There are guides all over the internet that can help you choose the right prop for your size/shape boat.

Is it it worth trying to run some kind of fuel additive thru it? Some kind of injector cleaner?

I’m going to try running it for the month before I pull it out of the lake for the season. Then I will dispose of the remaining gas and have the full tank stabilized. I will have this done and the injectors as part of the winterization- along with the water pump impeller. I suspect ithat has never been done - it’s working fine... just preventative since I have no clue what maintenance was done to this F115.

I talked to the marina- the guy I talked to said that they usually soak the injectors in some stuff - I can’t remember the name. Although he is not sure the guy that worked on my boat did. He acknowledged that this stuff was nothing in comparison to professionally cleaned. But he said a lot of crud came out of the VST tank.

rejesterd said:

Yes, you should remove the injectors and send them in to be cleaned professionally. Those can definitely get gummed up and clogged due to old fuel.

The plugs might be just fine, but they're so cheap, you might as well replace them.

If you find the same problem after that, then consider a different size/pitch prop. There are guides all over the internet that can help you choose the right prop for your size/shape boat.

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You can try SeaFoam, but I would at least run it off an auxiliary tank with fresh fuel for the rest of the season.

I added a couple cans of Seafoam before the VST was done. I probably can add more Seafoam as the tank has about 30 gals in it and I added 2 cans of Seafoam. I’ll check the seafoam instructions- maybe it can take some more? I ran it on a 2k rpm idle for a few hours yesterday - trying to get the Seafoam into it, but didn’t take it out on the lake due to the wind and my inability to dock it by myself - since I’m a newbie.

I’ll check with the marina- maybe they have a separate tank I can borrow. But that will kinda bite as there is no real good place to put it and it would need a long feeder hose.

Thanks for the help!

rejesterd said:

You can try SeaFoam, but I would at least run it off an auxiliary tank with fresh fuel for the rest of the season.

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An update... I had prev added ~2 cans of Seafoam and ran it on high idle for a few hours... I added 3 more cans (35 gal tank)... ran it on high idle for a few hours and then took it out on the lake with my wife and 2 kids... it seems like it was slow to start... then it sped up.... I was surprised. I was able to tube the 2 kids for a few hours before calling it quits.

Two days later I added 2 more cans of Seafoam - not realizing I burned about 15 gals the prior day on the water. I put 4 adults and 2 teens in it and it was DOG SLOW. I then dropped the boat to only having 2 adults and 1 teen and it was back to being faster - but it still felt like it took some time to get up to speed. It still feels underpowered. In general... should a 115hp be good for a 19' Hurricane? I would think so since it is a standard configuration.

I ended the day not realizing I burned the tank down to about 1/8. So... I will add 15 gals next weekend.

A couple of questions...
1) Should I use high octane and try and find E10?
2) Should I always put a can of seafoam in it each time I add 15 gals?
3) Should I try to find ethanol free gas near me... which I suspect I wont be able to.

Thanks !
LF

I'm still thinking that the injectors may need to be cleaned at the end of the season. I will have to do that with the water pump and sparks - I suspect the water pump was never done (17 years and 300 hours).

I doubt you did any permanent damage yet, but in general, try not to idle for more than 30 minutes or so. Hours-long idling can overheat your ECU, which can cause damage to other parts like the ISC. The owners/service manuals are pretty silent on this point, which is unfortunate.

However, it looks like a 115hp is the smallest engine they offer on a 19' model. Their lower range goes up to 150, and the higher range goes up to 200. (ref: https://www.hurricaneboats.com/centerconsole/cc-19-ob/build) So you might just be under-powered with multiple adults and kids in there.

A different prop or higher octane fuel might make a small difference, but I doubt the higher-octane fuel is worth the extra price you'll pay. I think regular top-tier E10 fuel is fine. If you can run the tank empty between fills, then that's all you need. But if you're like me and can't run your internal tank completely empty (without a big fuss, anyway), add a stabilizer like Startron or Yamaha Fuel Stabilizer each time you fill up. I've found that since I only use E10 fuel, I don't need the SeaFoam. The ethanol basically does what SeaFoam will do in terms of de-carbing and cleaning. It just doesn't stabilize (especially in the long-term) as well as other products.

Hi registerd - Funny how running at idle can damage something... but running strong with a load doesn't? Now I have something else to worry about.

Let me ask though... Im at about 1/8 tank now... is that what you consider empty? Or do you mean let it run at idle and let it 'konk' out? - and then fill it up? I was thinking of running it low at the end of the season and then have the marina suck out any remaining gas and dispose of it (@$10/gal). Would that clean out any crap that may be in the tank? Or maybe there is a way to clean an internal tank out?

Im hoping the fresh gas makes a difference and gives me a bit more speed. It just does not feel fast enough (and on a lake).. which makes me feel like something is just off. I cant imagine running it on the ocean with this power - or lack of power. Of course... the speedometer does not work either! - but it hit RPMs 5500 RPMs. I push the throttle and it hits a top speed... but then I push it more and nothing extra out of it.

I meant really empty.. like almost nothing in there. That really goes for smaller external tanks. So for yours, just use a stabilizer supplement.

I've never cleaned out my internal tank, but I don't see a reason to unless fuel delivery appears to be a problem. If you somehow got great performance when running off a small auxiliary tank with fresh fuel, then maybe it would be a good idea to have someone drain/clean your tank.

5500 sounds slightly low for max rpm, but it's within range.

I’m not quite sure 5500 was my max.. I’ll check this coming weekend. I do know that it maxes out and I can still push the throttle more- but no extra speed.

rejesterd said:

I meant really empty.. like almost nothing in there. That really goes for smaller external tanks. So for yours, just use a stabilizer supplement.

I've never cleaned out my internal tank, but I don't see a reason to unless fuel delivery appears to be a problem. If you somehow got great performance when running off a small auxiliary tank with fresh fuel, then maybe it would be a good idea to have someone drain/clean your tank.

5500 sounds slightly low for max rpm, but it's within range.

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5500 Is not that bad. I have dual 115's and was having a problem with old gas. I used k100mg and went from 4500 rpms top, to 5500. It went from surging, to running very smoothly.

I didn’t get the boat out last weekend- I prev had run the tank to about 1/8 and was afraid to go lower than that as I may konk out on the water. I then Added about 20 gals of new fuel so I will post an update after this coming weekend.

And of course last last time I had it out the prop clipped something underwater and one of the end fins on the prop is bent. Can those be straightened out?

SteveK999 said:

5500 Is not that bad. I have dual 115's and was having a problem with old gas. I used k100mg and went from 4500 rpms top, to 5500. It went from surging, to running very smoothly.

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LakeFake said:

I didn’t get the boat out last weekend- I prev had run the tank to about 1/8 and was afraid to go lower than that as I may konk out on the water. I then Added about 20 gals of new fuel so I will post an update after this coming weekend.

And of course last last time I had it out the prop clipped something underwater and one of the end fins on the prop is bent. Can those be straightened out?

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Yes, take it to a prop shop. We have a local one here that does a nice job on those.