Fuel Questions on my 2024 252SE

[Paul in Ohio]

Hi,
My Yamaha 252SE has 50 hours since I bought it new last year. I just noticed that the owner's manual specifies premium gasoline- 91 octane. I'm pretty sure that my engines are not supercharged or turbocharged; they are the standard 200 HP engines with standard 8.5:1 compression ratio.
I have been running 87 octane unleaded fuel from the auto service station since new, with zero problems. My boat will top out at 46 MPH. My understanding is that these computer controlled engines can adjust themselves to run on lower octane when detected, without pinging.
Of interest, my 2008 Yamaha WaveRunner FX-140 specifiies minimum octane of 86, and has a compression ratio of 11.4:1. I have run 87 octane ethanol fuel in it for 17 years without any issue.
Can people share their thoughts on using 87 octane fuel in their Yamaha jet boats? (I am not really interested in pursuing the ethanol vs. non-ethanol argument; I personally use 10% ethanol fuel in everything except lawn equipment, without issue)
A second question:
I read somewhere that there is no serviceable fuel filter on my boat, only a screen installed in the tank-mounted fuel pump, that is a pain to access. I am thinking of adding an inline fuel filter (similar to this one Amazon.com
My goal is to prevent the factory screen from EVER needing to be removed, by capturing any sediment in a good quality filter.
Any comments on the idea of adding inline fuel filters? Does anybody know what size i.d. rubber fuel line is used on these engines?

 

[FSH 210 Sport]

Your boat requires 86 octane, 86 recommended except for 255XE/255XD.


If you’re going to run ethanol laced fuel be sure to add Star Tron to prevent phase separation.

 

[Paul in Ohio]

Thank you! I misread in the specs section in the back, I must have been looking at the engine in the 255XE.

 

[drewkaree]

@Paul in Ohio here's some info I ran across, and was telling @FSH 210 Sport about this as well - you may find it interesting for your outdoor power equipment as well

Best Ethanol Fuel Treatment for Boat Engines - Practical Sailor

Since 1974, Practical Sailor’s independent testing has taken the guesswork out of boat and gear buying.

www.practical-sailor.com

I make no claims to knowledge or expertise, just sharing info so that others can potentially make better decisions for what they want to do.

I have run StarTron in my boat since new, and mix it with every container I use, so it's in all my 2-stroke fuel as well. I don't think their test was a perfect assessment of the StarTron, but even still, it was one of the recommended items in their test.

I found it educational, which is the reason I'm sharing it.

Happy boating!

 

[Paul in Ohio]

Thank you for a good read, @drewkaree. After careful consideration, my takeaway was not that I am going to start using StarTron, but that it sounds like a great idea to install a fuel water separation kit on each engine in my jet boat.
I am thinking to install this one so that I can watch for water through the viewport:

Amazon.com

I'm not exactly sure why each kit has four NPT ports, when it seems like only two are necessary, a FUEL IN and a FUEL OUT. Can anyone enlighten me?
Ah, I just figured it out. You can use either of the two FUEL IN ports, and either of the two FUEL OUT ports, for maximum installation flexibility in tight quarters.
Has anyone installed an aftermarket fuel/ water separation kit on their jet boat, and how is it working out for you? It seems like something that the factory should have included with each engine. It is standard equipment on larger inboard motors. Thanks

 

[FSH 210 Sport]

This is the problem with ethanol fuel.

Phase Separation in Ethanol Blended Gasoline - Enertech Labs

enertechlabs.com

I’m one of the people that has had phase separation happen to, it was in one of my fuel injected dirt bikes and it destroyed the fuel pressure regulator. That was bad enough in and of itself, but it also cost me a day of riding with one of my friends after a two hour drive to the desert. I had never heard of phase separation at the time and it took me a while to diagnose what had happened. I was able to remove the 2.5 gallon tank, dump that crap out, rinse / clean the tank and replace the fuel pressure regulator. In our boats there is a filter at the base of the fuel pump assembly and there is a fuel pressure regulator in the fuel pump assembly, excess fuel is returned to outside the fuel pump assembly. I’ve also repaired a fair number of power sports and lawn care carburetors that were either clogged or damaged by ethanol fuel going bad, most of the time the pilot jet gets clogged and has to be cleaned out, but sometimes it’s corroded and has to be replaced.

While in line fuel filter water separators will remove any free water, you have to keep in mind that water bonds instantly with ethanol or any alcohol so the water is no longer free, it’s suspended in the ethanol which is in the gas so it’s not going to get separated by the in line water separator. When you buy gasahol or ethanol laced fuel, you don’t know how “wet” the fuel is, then you’re running your boat in a very humid environment wherein the humid atmosphere is drawn into the tank through the vent as fuel is used. If you’re burning a lot of fuel it’s far less of a problem, but most people don’t burn that much fuel so the gasahol is not replaced with fresh fuel regularly and can become loaded with water. Is it good to run a tank of gasahol occasionally? Yes, the ethanol acts as a fuel system water remover and the solvent aspect of the ethanol will provide some cleaning. I usually run a few tanks a year because non ethanol is not available where I’m at. See the mention about that in the linked articles below

If you want to keep your fuel system clean run Top Tier gasoline which has Techron in it. Yeah it’s a little more money but it’s worth it. The fees actually specify a certain level of detergent in gasolines. Just like non ethanol fuel, it’s a bit more per gallon but it eliminates the problems associated with gasahol and non ethanol fuel has more btus per gallon. If you go to a service station and the pumps and nozzles are filthy how often do you think the filters on the pumps are being changed? Gas stations that move a lot of fuel are also the best bet to get the driest fuel since so much fuel is being moved through their system.


As talked about in the linked articles below there is no additive that will totally eliminate the risk of phase separation, but those additives do help.

Busting Ethanol Fuel Myths | West Marine

West Marine is committed to outfitting your life on the water. With over 250 store locations, 100,000 products in stock, and knowledgeable Associates, trust West Marine for your boating, sailing, fishing, or paddling needs. Shop with confidence - get free shipping to home or stores + price match...

www.westmarine.com

https://www.chevronlubricants.com/content/dam/external/techron/en_us/sales-material/all-other/Technical%20Presentation-Techron%20Marine%20and%20Powersports%20Small%20Engine.pdf

Spend the time and money of installing fuel filters / water separators on tanks of good gas and go burn gas on the water.