How does Yamaha math work? 210 fsh fuel

[ShireRider]

I have been running close to shore. I see my local marina switched to VP fuel so I ran my tank down.

The gauge said 24% this is on the water.

I just pumped 46.8 gallons into a 50 gallon tank.

Is the gauge that far off? I’ve put in 25+ gallons at 78%.

What am I missing?

 

[Coult45]

@210 FSH will give you a better answer than me to help you maintain a pretty accurate estimate of your remaining fuel. I'll just reinforce your opinion that the gauge is not to be trusted...my gauge has only shown a percent remaining number in the 90's once in three years. It shows 100% for a while, then drops straight to 87%. It then wanders slowly and inconsistently down until I fill it back up. My trips don't run me that low, and I carry gas cans to my dock a few times a week, so gauge accuracy just hasn't been important enough for me to worry about it.

But you're right, it's not to be trusted as your only source of truth. I'm guessing the angle on the trailer vs the angle on the water makes a significant difference too.

 

[ShireRider]

I'm guessing the angle on the trailer vs the angle on the water makes a significant difference too.

I’ve been in the water all summer, I can confirm that I was at 24% when I docked a few weeks back & the “gauge” was giving the same reason.

I was surprised because I expected it to get a little more accurate (if that’s the right sentiment) as it got closer to zero. I expected to be able to take 40 gallons max.

I am glad that I followed my own advice & did not let it get lower than 1/4 on the needle.

Side note… they had some cool VP race fuel stickers I was allowed to take for my cooler & my boys to put on their dirt bikes.

 

[TeenGee]

When I had a 2022 210FSH Sport, I would raise the stern and fill the tank until I saw fuel in the filler (Please don't flame me for over filling). At that point, I considered the tank full. On the water the gauge would read 100% until the Connext indicated I had burned about 10 gallons. Each time I filled the amount of fuel to get back to full was within 1/2 gallon of what was indicated on Connext. For example I would run until the gauge indicated 50% and Connext indicated 35 gallons burned. Refilling would take about 35 gallons. The conclusion I drew was that I was consistently able to carry 60 gallons in the tank on my 210FSH.

 

[FSH 210 Sport]

Thanks @Coult45

Firstly, according to the manual the fuel tank in the 210 FSH has a capacity of 52 gallons and not 50 as was shown on the web site and app pages.

Second, a boat, our boats are always moving and are rarely level, so where your standing to where and what load you have on the boat makes an impact on what the percent fuel gauge reads, it’s a boat not a car.

Thirdly, when the diameter and length of the fuel line is taken into account, how a fuel pump at the station might work in regards to how it clicks off, and the angle of the boat (as @TeenGee mentions) there could be a variability in the fill up of several gallons at fill up.

@ShireRider are you getting your fuel at the same pump / station each time you fill up? Looks as if the amount of fuel you fill up you have mentioned on two occasions has been high.

I’ve run my boat down very low on fuel once so I would know how much useable fuel there was in the tank, it was so low that whilst idling at the dock the starboard engine shutoff, but the starboard engine re started when on the trailer. I think the fuel gauge read 1 or 2%. When I filled the tank up it took almost 52 gallons, and I didn’t keep clicking the pump handle. Conclusion is that at best cruise on calm water, in the 25-27 mph range almost all if the fuel is useable.

As @TeenGee eluded to, there is a fuel used monitor in the connext screen, it’s the icon that looks like a flattened U shape at top screen tray, it is digital and reads to 10ths of a gallon. This particular screen has other readings as well, avg mpg, max speed, avg speed (I think), gph, and total engine hours, and this screen is resettable (with the exception of total engine hours) and of course must be re set to utilize those functions. I have found that without exception the fuel used gauge is accurate to within 1-2 10ths of a gallon in the total amount of fuel used 99% of the time it is accurate to 1/10th of a gallon and only once was it off by 2/10th’s of a gallon at fill up. So, let this fuel used meter be your guide at fill up to know how many gallons of fuel should be required to fill the tank up, and how much fuel you have left in the tank whilst on the water, for me it’s fill at the slowest set and forget rate on the pump handle until it clicks off, wait 15 seconds and then one more try with the pump handle until it clicks off again. Just filled up day before yesterday, connext screen showed 36.0 gallons used, the fill up using the aforementioned method clicked off at 35.5 gallons, then second attempt brought it up to 35.949, so pretty damn accurate.

The risk you run with continuing to top off your tank is getting fuel into the carbon canister on the vent line, if enough fuel gets in there the vapors cannot vent through the canister and will result in a very slow fill experience at the pump. For example, if you put in enough fuel to where the fuel level is right there by the cap the fuel level in the fill hose is above where the carbon canister is and could cause liquid fuel to fill the carbon canister. Not flaming you @TeenGee just stating what could happen. Having said that, @TeenGee was crafty in putting the nose of the boat down which puts the fuel fill hose inlet and vent fittings on the high side and lets the tank completely fill as it eliminates any air pockets in the tank, kinda reminds me of how I fill my dirt bike tank before a really long ride, I sort of burp the tank by rocking it back and forth on the center stand after it’s full.

The percent full fuel gauge on my boat is relatively accurate and is a good gauge to read at a glance while underway but my go to is the fuel used meter. Now that I think about it I’ve only seen my percent gauge read 90% once or twice, I’ll echo what @Coult45 said, it always seems to drop to 86% or so.

The last thing I’ll mention is that some of the boats with 40 gallon tanks were having issues with the percentage gauge being off wildly, running the tank down low before refilling fixed that problem. @ShireRider was this the first time you have run the tank down into the 20% range?

 

[ShireRider]

Thanks @Coult45

Firstly, according to the manual the fuel tank in the 210 FSH has a capacity of 52 gallons and not 50 as was shown on the web site and app pages.

Second, a boat, our boats are always moving and are rarely level, so where your standing to where and what load you have on the boat makes an impact on what the percent fuel gauge reads, it’s a boat not a car.

Thirdly, when the diameter and length of the fuel line is taken into account, how a fuel pump at the station might work in regards to how it clicks off, and the angle of the boat (as @TeenGee mentions) there could be a variability in the fill up of several gallons at fill up.

@ShireRider are you getting your fuel at the same pump / station each time you fill up? Looks as if the amount of fuel you fill up you have mentioned on two occasions has been high.

I’ve run my boat down very low on fuel once so I would know how much useable fuel there was in the tank, it was so low that whilst idling at the dock the starboard engine shutoff, but the starboard engine re started when on the trailer. I think the fuel gauge read 1 or 2%. When I filled the tank up it took almost 52 gallons, and I didn’t keep clicking the pump handle. Conclusion is that at best cruise on calm water, in the 25-27 mph range almost all if the fuel is useable.

As @TeenGee eluded to, there is a fuel used monitor in the connext screen, it’s the icon that looks like a flattened U shape at top screen tray, it is digital and reads to 10ths of a gallon. This particular screen has other readings as well, avg mpg, max speed, avg speed (I think), gph, and total engine hours, and this screen is resettable (with the exception of total engine hours) and of course must be re set to utilize those functions. I have found that without exception the fuel used gauge is accurate to within 1-2 10ths of a gallon in the total amount of fuel used 99% of the time it is accurate to 1/10th of a gallon and only once was it off by 2/10th’s of a gallon at fill up. So, let this fuel used meter be your guide at fill up to know how many gallons of fuel should be required to fill the tank up, and how much fuel you have left in the tank whilst on the water, for me it’s fill at the slowest set and forget rate on the pump handle until it clicks off, wait 15 seconds and then one more try with the pump handle until it clicks off again. Just filled up day before yesterday, connext screen showed 36.0 gallons used, the fill up using the aforementioned method clicked off at 35.5 gallons, then second attempt brought it up to 35.949, so pretty damn accurate.

The risk you run with continuing to top off your tank is getting fuel into the carbon canister on the vent line, if enough fuel gets in there the vapors cannot vent through the canister and will result in a very slow fill experience at the pump. For example, if you put in enough fuel to where the fuel level is right there by the cap the fuel level in the fill hose is above where the carbon canister is and could cause liquid fuel to fill the carbon canister. Not flaming you @TeenGee just stating what could happen. Having said that, @TeenGee was crafty in putting the nose of the boat down which puts the fuel fill hose inlet and vent fittings on the high side and lets the tank completely fill as it eliminates any air pockets in the tank, kinda reminds me of how I fill my dirt bike tank before a really long ride, I sort of burp the tank by rocking it back and forth on the center stand after it’s full.

The percent full fuel gauge on my boat is relatively accurate and is a good gauge to read at a glance while underway but my go to is the fuel used meter. Now that I think about it I’ve only seen my percent gauge read 90% once or twice, I’ll echo what @Coult45 said, it always seems to drop to 86% or so.

The last thing I’ll mention is that some of the boats with 40 gallon tanks were having issues with the percentage gauge being off wildly, running the tank down low before refilling fixed that problem. @ShireRider was this the first time you have run the tank down into the 20% range?

I appreciate the awesome responses. (I’m the same boat trying to figure out top end/loss of speed for the past few weeks, I’ll mention that after responding to your post above).


I’ve had my boat in a slip all summer. There are 2 choices for fuel… I was advised not to use the one because other people at the marina have had trouble with fuel quality, so I have exclusively been going to the same station. The pumps are certified by the county auditor, I checked for the sticker after filling this time. All summer they had been shell, but just switched to VP.

I did not even consider using the connext fuel used interface. That is great advice.

I don’t believe I have ever run my boat lower than 50%. Until this year I would refill the boat after every trip. Now I have to be going past when the fuel station is open & I typically like to fill up when I’m solo because I don’t need my friends/company to feel pressured to chip in for fuel (I’m fortunate to be able to afford fuel & a boat so I’m just grateful for the company).

@TeenGee I believe the 60 gallon number, but will not be planning an offshore trip around that. Lol. I’ll still take the 50 gallons with 1/4 reserve back at the dock should I ever put myself in that position & I will likely have a few cans of fuel on hand just in case