fuel gauge accuracy

[sam]

I do not rely upon the indicated level as shown on the fuel gauge, but keep a solid record of all fuel used. (averaging 0.7 GPH over time-no generator). However, I would like for the unit to roughly indicate some state of fill other than perpetually full. I have not attempted to sort out this issue yet, but thought I would ask the all knowing list for experience first.

This forum has really become a source of help and sharing.

Sam

LONGHAWK

[Alan]

Sam,

 

It's good that you do not rely on the reliability of the fuel gauge on your boat. The guage has no real accuracy even when it's working.  In calculating the consumption I use 1 GPH to be safe.   When I purchased my boat, it registered full on the fuel guage always.   I  found that the sending unit was installed incorrectly.  So my advice is to look at the sending unit first as this is where the problem is most likely.  

 

Alan

Plan B

[Jeff Shukis]

I've been planning to do the same. Since I don't have a generator, my plan is to utilize the second 5-bolt opening in the fuel tank to install a capacitive NMEA2000 fuel level sender that supports tank-shape calibration. The Offshore Systems unit fits the bill, but it seems that they have to do the calibration.

 

Jeff

[Jeff Shukis]

I did install the NMEA2000 fuel level sensor and it has been working perfectly. By the way, my factory fuel sender has always been just fine - no problems at all.

[Mike Brown]

Sam, even if you get the sending unit working correctly you have to keep in mind the tank is not square on the bottom. It's tapered to fit the shape of the hull and once you get down to about a 1/3 of a tank the float thinks you have more fuel than you actually do. Fortunately mine seems to work fairly well but just the same I don't like to allow it to get too low not trusting the guage. This is also the case with the 40, 46, 49 and 50 models. Not sure of the 37 or smaller boats though.

Mike

[can kurdoglu]

 

Non of the fuel gauges are operating on Beneteau's..The reason is the  float with an arm that extends under the top lugs of the tank and the float squeezes on the walls along the ceiling of the tank and does not operate...If a float type that operates on a shaft is used this problem will be solved until eternity...

can kurdoglu 

[foster]

Hello,

Since the first day I have had this problem. Beneteau after 2years waiting did a software update that did not change anything. So I do like all of you estimate the diesel consumption 2,5L/H. But this is very inaccurate and can get you in problems.

I am exploring the possibilities to have an accurate tank (fuel, water and waste) system. For the moment I was thinking of using the Mastervolt Easy view I already have for battery monitor (works perfectly well) and for genrerator. I also saw some sensoreless systems or pressure systems made my "Progress". If someone has a reliable system to solve this problem I am sure most Beneteau owners would highly appreciate.

 

Denis

 

PS Amel has a very reliable system direct vision through a calibrated tube

 

 

[clayton curtis]

Sam,

 

I had the same problem and my dealer said it is the number one thing they replace on all new bene's. I had mine replaced and it still failed after working for a week or two.

 

I actually ran out of fuel in the ICW with the VDO sitting on 3/4 full!  Sea Tow to the rescue!

 

I purchased and installed a new low-tech but reliable sensor and needle-type gauge that I bought from WEMA cheap.  http://www.wemausa.com/

I drilled a hole for the gauge to sit in on the wall near the throttle so I can actually SEE the gauge when I'm filling the tank. Crazy idea, huh?  In the past, I had too many episodes where my mate yelled from down below, "Stop, it's almost full!", just as the diesel overflowed.  It's worked perfectly and reliably.

 

Here's a few tips if you decide to do this:

1.  Be aware that the tank is funny shaped such that there is fuel that can sit "above" where the sensor mounts.  That's why VDO uses a float attached to an arm.  Therefore, when you use a tried and true float on a pole, it will register full before it is actually full - just a few (2-3 gallons).  Not a bad thing as we have not overfilled since.

 

2.  Full is not full with the WEMA, but empty is empty!  We confirmed this and did a few tests with jerry cans of diesel so that we know exactly what the needle reads when we are empty, and have 5 gallons left.  Sometimes we like to live on the edge. However, you have to measure the depth of the tank from the top hole to the bottom to select the right sensor.  Anticipating that someone might ask, hey Clay, what is the depth of the tank?  I don't remember.  I got it at the Miami Boat show and installed it and don't remember and can't find a record. Damn Rum! Doh!  Anyway, I wouldn't recommend buying without measuring anyway.

 

3.  In order to do the switch, you have to get your tank to at least 1/3 empty or you will get diesel everywhere as sloshes around. Also, note that you have to pull up the entire floor in the port laz to get to it. Pain.

 

4. MOST IMPORTANTLY!!!!!  The 5-hole sensor has one position and one position only.  However, IT IS NOT KEYED!!!! It really looks like the sensor has 5 evenly spaced holes and you could screw it on in any orientation.  NOT!  I did this and diesel leaked into the bilge.  Last time I had that much fun was when I used to use airplane glue to build models.  Make sure that the orientation is correct and it will not leak.  The sensor comes with a new gasket.  

 

5.  You have to be willing to give up the fuel reading on the VDO downstairs.  Both will not work. 

 

WEMA has several versions, but I selected a chrome and white face -looks sharp and OEM. It comes with a LED light too so you can see it at night. 

 

Hope this helps!

 

/cc

 

[Bruce Coward]

Guys,

An update on Jeff Shukis post re the Offshore Systems Volumetric Fuel Sender posted Jan 9: This sender can be volumetrically calibrated from an Offshore Systems 3340 MultiFunction display http://www.osukl.com/3340.htm by the user or the company can calibrate from tank drawings or a depth to volume table generated on a dip stick at no extra charge.

Cheers

Bruce

 

[Jeff Shukis]

Thanks for the info Bruce. I installed the sensor last week and then filled up the tank five gallons at a time, taking % full measurements after each fill. This should be enough information to get a pretty good calibration.

 

Jeff Shukis

[foster]

Hello,

This flow meter works only with gasoline engines.

Diesel like the Yanmar aspirate more fuel than used, the excess is sent back to the tank.

 

I think an accurate tank monitor is more reliable when it works.

 

Denis

[Jeff Shukis]

The Floscan system look rock solid, but extremely expensive at around $2,000 for parts only. Why so expensive? A diesel needs two flow sensors and a module - either a display or their NMEA2000 module - to do the calculations. For pure geek factor, it's tempting, but on a small sailboat fuel consumption just doesn't seem that critical.

[foster]

Hello,

 

I have decided to install a new fuel (and water) monitoring independent from the VDO system.

 

I will probably use a Mastervolt analog to digital converter after checking that the factory mounted sensor is accurate and compatible. Using Mastervolt easy display it will be compatible with the rest of the network and the Raymarine E80.

 

Has anyone done this or something similar with or without changing the factory mounted tank sensors. ?

 

Denis