Fuel Gauge Accuracy

[colecaz]

I have a new to me 2005 209 Escape with a Yamaha F200 engine and the digital tach and speedometer. The fuel tank gauge on the speedo gauge is not at all accurate and I'm wondering if this is typical. I have an 80 gal tank and twice have filled it when it is showing around 1/4 tank, only to have it take around 45 gal to fill. When full, it shows full.

Is this normal or is the sender possibly bad?

 

[seasick]

Normal,
The gauge if you are referring to the bar display indicates about 20 gallons when it is at one bar AND starts flashing.This is with a relatively level boat hull Of course if you have a loaded stern and a few people back there you will read an even higher tank level since the angle of the tank now moves the fuel towards the stern and gives an even less accurate reading. So if you are level and the lowest bar flashed figure 20 gallons left. If you trimmed bow up with a load in the stern and the bar flashes, get your TOW US number ready if you are off shore.
Over time you should get to know approximately how much fuel you have in the tank. Do not relay on the guage.
On my 208 ( same tank) each bar represents about 10 gallons. When two bars changes to one, there is about 30 gallons left. When that one bar flashes, there are about 20 gallons left.
So if 1/4 full to you is two bars, there are somewhere between 30 and 40 gallons in the tank. Its an 82 gallon tank so a fill up would be 42 to 52 gallons (give or take) when the display changes from three bars to two.

 

[gw204]

I use the standard type of fuel gauge (that relies on an in-tank sender) for show only. To accurately measure your fuel usage/level, you need a fuel flow meter. Inexpensive ones like the old school Navman (Northstar, Lowrance, etc.) are best suited for use with older engines because the flow calibration isn't as accurate as the more expensive ones (Floscan, Yamaha, etc.).

You could add a Yamaha fuel flow meter to your engine very easily...they aren't cheap though.

 

[Curmudgeon]

Inexpensive ones like the old school Navman (Northstar, Lowrance, etc.) are best suited for use with older engines ...

My NavMan is accurate to 1 gallon in 90. All it takes is tweaking the gage reading v. actual numbers. The later models have better transducers and hard plastic nipples. First used it on an '03 Suzuki 140, GPH readings are still rock steady on an '03 Honda 225 using 10 sec updating ... :uhm

 

[colecaz]

Seasick, sounds like you are experiencing the same readings as I am. Recently I showed 2 bars most of the time, occasionally flashing up to 3, and when I filled up it took 46 gallons. Since 2 bars is 1/4 of the 8 bars on the gauge, I expected to put in around 60 gal. Not so.

I was hoping that the gauge would be a little more accurate but it sounds like it is what it is and I'll have to figure out what it really means. For now, 2 bars = 30-35 gal remaining.

Thanks for the comparison.

And gw204, thanks for the suggestions about the fuel flow gauges. I had FloScans on my Krogen and they worked great, but I can't see the cost for a near-offshore rig. My policy is not to leave for beyond 10 miles without a full tank..

 

[seasick]

Seasick, sounds like you are experiencing the same readings as I am. Recently I showed 2 bars most of the time, occasionally flashing up to 3, and when I filled up it took 46 gallons. Since 2 bars is 1/4 of the 8 bars on the gauge, I expected to put in around 60 gal. Not so.

I was hoping that the gauge would be a little more accurate but it sounds like it is what it is and I'll have to figure out what it really means. For now, 2 bars = 30-35 gal remaining.

Thanks for the comparison.

And gw204, thanks for the suggestions about the fuel flow gauges. I had FloScans on my Krogen and they worked great, but I can't see the cost for a near-offshore rig. My policy is not to leave for beyond 10 miles without a full tank..

Here is how I approach it. Most of my trips average in the 15 to 20 gallons range, mostly bay and inshore fishing.

Based on what I have in the tank and how much fuel I plan on burning, I add gas accordingly. Remember that every 20 gallons of extra fuel is like carrying another passenger. That weight reduces efficiency and affects performance. In addition, since I add fuel in smaller amounts and usually use it up on the next outing, I am constantly refreshing my fuel. It doesn't get stale and I don't add any stabilizers. I rarely have more than 1/2 to 3/4 tank and I rarely get to the flashing one bar state ( which is pretty scary if you are fairly far out). If I plan on a longer excursion, I gas up accordingly.
You will find that depending on the fuel level and your load ( people), the number of bars can change by 2 when everyone moves from the stern to the helm, so take the angle of the boat into account.

 

[Gary M]

Do you guys have the Yamaha Fuel Management System gauge? I use the amount of fuel used from the FMS and subtract that from a full tank which is a known quantity. My FMS reads out about 3% more fuel used than actual which keeps me on the side of being conservative when the gauges get down near the one bar range.

I filled up yesterday in preparation for an upcoming Bimini trip and the FMS said that I had burned 249 gallons and it took 242 to fill it up. Close enough for me!

 

[Grady_Crazy]

Normal,
The gauge if you are referring to the bar display indicates about 20 gallons when it is at one bar AND starts flashing.This is with a relatively level boat hull Of course if you have a loaded stern and a few people back there you will read an even higher tank level since the angle of the tank now moves the fuel towards the stern and gives an even less accurate reading. So if you are level and the lowest bar flashed figure 20 gallons left. If you trimmed bow up with a load in the stern and the bar flashes, get your TOW US number ready if you are off shore.
Over time you should get to know approximately how much fuel you have in the tank. Do not relay on the guage.
On my 208 ( same tank) each bar represents about 10 gallons. When two bars changes to one, there is about 30 gallons left. When that one bar flashes, there are about 20 gallons left.
So if 1/4 full to you is two bars, there are somewhere between 30 and 40 gallons in the tank. Its an 82 gallon tank so a fill up would be 42 to 52 gallons (give or take) when the display changes from three bars to two.

I took my 208 out last weekend and was watching the gas guage since I was running on last year's gas and wanted to burn it up before refueling. Mine got down to 1 bar and when I filled it up took 50 gals. Exactly the same as seasick said. :goodjob

 

[ric2352]

Noticed what all you guys dud with my gauge, but not as severe. I pulled the sending unit when the tank was full ( mine wouldn't read completely full) and bent the float arm down til it read full.....doesn't take much bending....more accurate thru the whole range now.