Inaccurate gas level reading?

[adamncincy]

So I was running a bit low on gas and knew that I'd be taking it out of the marina to take the AR210 to a lake soon but knew I'd be on the river for a few hours. Knowing that the dockside gas was $4/gal I put about $50 in and thought this would be plenty, until I took it out.

After a few hours of cruising with friends, the engines wouldn't start. The first thing I do is check the gas gauge. I had a little less than a 1/4. More than enough, right? At least to take it back to the marina.

Long story short, a nice couple gave us a tow to gas that was about 70 feet away. I added about $60 and the problem went away.

So, yes it was obviously gas.

Why would my gauge read I had "enough" and why would $50 @ $4/gal only yield a few hours of cruising, when I filled it up @ $90 @ $3/gal (50 gal tank) and was able to get about 15 hours of hard riding in? - I'm lost.

 

[fatboyroy]

If it’s too low I think boat movement in water could easily starve gas line if you truly have 1/4 tank left if you tried again it prolly will start once fuel pump fill the gas line again.

edit: fill up the tank and see how much to fill it up So you know when you get to 1/4 level how much gas you have left

 

[itsdgm]

My gauge was pretty inaccurate when I bought the boat. I had to recalibrate the sending unit. It’s been spot on ever since. Not sure if yours is the same.

 

[mrcleanr6]

Keep in mind if you are reading while the boat is underway then the fuel will read higher. The floats are in the aft of the tank so if you have a bunch of people at the back of the boat then it will read high also. If you get 15 hours if riding for 90 bucks then you should feel privileged lol. Keep that tank topped off anyway

 

[adamncincy]

This is all good input and appreciated!

Let me ask you this ... 2 points ...

Physics here, the more gas in the tank, the heavier the weight, the heavier the weight, the lower the gas mileage, BUT .... I never want to run out of gas again on the water! haha ... What's everyone's thought process here?

Second, @mrcleanr6 let's just say I want to get a good gas reading, would it be beneficial to have everyone move to the bow for a second?

 

[adamncincy]

Also, I'm a huge proponent of SeaFoam, I've used it for years, way before I owned a boat and it's literally been a miracle in a can. Has anyone used this for improved gas mileage/hourage (lol) and seen solid results?

 

[mrcleanr6]

Not in the bow. More in the middle of the boat. You just want the boat to sit naturally in the water.

 

[212s]

Why would my gauge read I had "enough" and why would $50 @ $4/gal only yield a few hours of cruising, when I filled it up @ $90 @ $3/gal (50 gal tank) and was able to get about 15 hours of hard riding in? - I'm lost.

I think your numbers are off...or you were not paying attention to real time while having fun.

Here's some math to explain what happened.

$50 / $4/gal = 12.5 gallons = 1/4 tank

$90 / $3/gal = 30 gallons = 2/3 tank

A "few hours of cruising" would be roughly 2/3 tank - explains why you ran out and gauge is probably not showing it empty. Verify your fuel gauge is working properly. If not, make sure you fill up before going out and expect 4-5 hours of fun.

No way you did 15 hours of hard riding even with a full tank - max range cruising is about 5 hours - boat consumes about 12gph cruising at 30mph with MR-1 engines and with a tank of 50 gallons that's a max of almost 5 hours. Lots of WOT at 31gph and you're looking at 2-3 hours of fun.

My boat is similar but a bit more efficient and a typical 90 mile cruise consumes half a tank or 25 gallons and 2.5 hours of fun, max cruising is about 5 hours and 180 miles. This assumes calm waters and light winds. Add either, plus more weight, water sports, idling time, etc. and your range drops 20-30% depending on activities.

Sounds like you're getting typical range and consumption.

As for fuel gauges...mine reads accurate when idle, and adds about 5% when cruising on plane as the bow is a few degrees higher and pushes the fuel to the rear of the tank. So when cruising I deduct 5% and that gets me a fairly close reading. My boat sets off an alarm when fuel drops to 15% so I never let it get that low...the alarm is annoying.

 

[drewkaree]

When I'm at speed, my gauge tends to read about 15-20% more than when at rest/stopped. As @mrcleanr6 points out, everything shifts back, perhaps giving you a false initial reading. Next time you take it out, check out the difference in the fuel gauge between a dead stop and when at speed. Don't trust it below 30% or slightly over a quarter tank. You COULD take a 2 or 5 gallon container of fuel with you to allow starting the boat, and then don't let off until you're closer to fuel, but that seems like more of a hassle - just throwing ideas out there.

 

[FSH 210 Sport]

This is all good input and appreciated!

Let me ask you this ... 2 points ...

Physics here, the more gas in the tank, the heavier the weight, the heavier the weight, the lower the gas mileage, BUT .... I never want to run out of gas again on the water! haha ... What's everyone's thought process here?

Second, @mrcleanr6 let's just say I want to get a good gas reading, would it be beneficial to have everyone move to the bow for a second?

Your physics are spot on!

If you want to be sure you never run out again, just fill it up each time you use it on the way to the water. Gas is less expensive away from the water anyway. Filling up this way keeps the cost per fill up down.

Your smart phone should have a level built into it, check how level the boat is at the gas station, check front to back and side to side, and check the fuel gauge before filling, does the fuel gauge jive with how much gas you put into the tank? Start keeping notes on the gauge level and amount of fuel put in so you get to know your gauge. You can also use your smart phone level to check how the boat is sitting in the water, and check that against your fuel gauge.

I recently did a run down test on my boat, when it got to 1% I was close to the dock and headed back to it, while idling at the dock my starboard engine died, put the boat on the trailer with the port engine. Once on the trailer the starboard engine started right up. As the others have said the fuel moves around in the tank and may settle to one side or the other.

As far as additives go.. really the only way they will give any noticeable increase in mpg is if the injectors are dirty and not atomizing the fuel like new ones would. The easiest way to make sure you are getting the maximum fuel efficiency is to run octane fuel that the manual states, and make sure the air filter and inlet tract(s) are clean and unobstructed. I do not have any experience with sea foam, but do with Techron. Techron, whether injector cleaner or fuel system cleaner works very well in my experience. I’ve also started using Amsoil upper cylinder lubricant along with Amsoil fuel system cleaner. Having said that, it is my understanding that the Yamaha Fuel MedRx (if I have that right) also works well. What ever you are using just make sure you use it regularly as that will keep the entire fuel system clean.

How do your plugs look? Is the insulator while all the way down inside the plug? If not that may warrant further investigation, such as making sure the MAP sensors are working within range and or dirty.

I don’t know if your boat has the connext screen with fuel used or not, mine does and that is pretty darn accurate, and my fuel gauge is pretty accurate as well.

You could always pull your fuel tank sending unit ( gas gauge level sensor) out and inspect it to make sure it is clean.

 

[adamncincy]

@212s I already had fuel in it before topping it off!

During my 3 trips taking it out after filling up ... my riding was very inconsistent as this was spring and I was checking everything out, even riding on one engine at times, etc.

I like the idea of using the accelerometer/gyroscope built into the smartphones! Never thought of that.

 

[Shir9406]

I tend to reset my “fuel used” on the connext screen every time I fill up! That way I can track exactly how much fuel I have used and need… my % on the Home Screen is usually always off…

 

[212s]

@212s I already had fuel in it before topping it off!

Not trying to argue but it doesn't matter really...you can't change the consumption rates...your boat consumes a specific amount of fuel at specific rpm levels and you simply can't do more than about 4-5 hours of cruising without adding more fuel. You simply couldn't get 15 hours of hard riding in without filling up at least 3 times, you would need about 150 gallons of fuel for 15 hours of use. Here's a link to the Boattest.com site for a 2011 AR210 which should be the same for your model:
Yamaha AR210 (2011-) | BoatTEST
They give a cruising range of 109 miles plus reserve which should get you about 120 miles before running out of fuel and about 4 hours at 31mph. Their numbers are not always exact, but it gets you in the ballpark.

During my 3 trips taking it out after filling up ... my riding was very inconsistent as this was spring and I was checking everything out,

Exactly my point...hard to figure out what you used without monitoring usage and how much it takes to top up again. Unless I'm running it down to get rid of older fuel in the fall, I top up all summer every time I go out so I know how much I use when I top up again. When standing at the pump, I can guess when the pump will kick off and I'm usually within about a gallon (4 liters up here) of guessing right.

As @Shir9406 wrote, I've reset the trip a few times this year to see if it concurs with my fuel pump data and it's surprisingly accurate - never had fancy electronics before so this is still kinda new for me. Regardless I like a full tank when I go out...never know what we might decide to do and don't want to get stuck empty somewhere miles from a fuel dock.

even riding on one engine at times

At no wake speeds I hope...you could flood the non-running engine with water from the cooling system due to pressure build up...don't want that.

 

[adamncincy]

@212s I could be off a little ... just guestimating. I also probably consumed 1 or 2 adult beverages ... maybe more, but whos's counting!

So mine is a 2010 AR210, I only have the manual gauges, but I guess I could still mark the needle. Actually, that's what I'm going to do and I think you guys are offering the best advice, just fill up when possible! I don't like doing that on the mighty Ohio with gas prices the way they are, but I also never want to run out again! lol