Fuel gauge error?

[Long Trail]

Fuel tank is full.
The fuel gauge is reading half?
Any ideas?

[Threeweight]

Is this something that just cropped up, or has it been doing it a while?

Could be a bad spot in the wiring between the sending unit and gauge.  Sending unit could be sticking (if it is the standard kind, there is a wire swing arm in there with a float on one end, not very accurate to begin with and can jam, and the float can lose some buoyancy).  Could be an issue with the gauge itself (unlikely).

I'd start by inspecting the wires at the back of the gauge... gauge posts look good?  Any corrosion on it, or the terminals on the wiring?  Is the wiring itself good and flexible, or does it feel stiff and brittle?  Do a similar inspection at the fuel tank, where the sending unit mounts.  Check for any loose connections.  Try shifting your weight from side to side in the boat, to make the fuel in the tank slosh around... does the needle on the fuel gauge move?  If not, likely bad wiring or bad sending unit. 

If you want to replace the sending unit, look into the Wema units as a replacement... more accurate than the swing-arm types for about the same $$:

http://www.wemausa.com/tank_sensors/tank_level_sensors.htm

[Long Trail]

Thank you.
The needle moves.
The wiring is good.
Let me try to shift the weight in the tank.
I will let you know if it works.

Thanks again,
Jm

[58Johnson]

My Wema guage recently said empty at the dock. Pulled boat, went to gas station. Only took 8 gallons till full (27 gallon tank). Ended up barely being able to get up on plane with full tank, full gear and two guys. Now I pull the back panel to visually check the level before I leave home - every time!

[Hunter]

I don't ever trust fuel gauges on motorcycles, boats or airplanes.   Better to have a fuel flow meter and/or NMEA-2000 engine data to track actual fuel used...... that and the time tested rule of thirds...   JMHO

[Summertime Blues]

 :yeahthat:I don't even look at my fuel gauge. Always take the cover off and visually inspect the tank level before every trip.

[Ko Ho]

I don't ever trust fuel gauges on motorcycles, boats or airplanes.   Better to have a fuel flow meter and/or NMEA-2000 engine data to track actual fuel used...... that and the time tested rule of thirds...   JMHO

Never had a boat fuel gauge that was accurate enough to count on, so I didn't even bother to install one when I bought my Arima new several years ago. I just pull the cover and look at the tank. BTW, those markings on the tank seem pretty accurate.

[Yachter Yat]

   I agree. Just my opinion of course, but a fuel gauge on an Arima?.........How about a "you know what" on a bull.  Ha


Yat

[hurstian]

anybody know how to reach the back side of fuel gauge? Looks like the top section is a single piece, so is the bottom section. I heard it's pretty easy to access fuel gauge, but it doesn't look that way from my boat.

[Hunter]

My thinking is that fuel is like beer.....  Your going to drink it sooner or later so might as well be fully stocked.   Your SL22 has a 102 ga tank so my advice would be to just keep it full...... enjoy your day and when you fill up..... get a general idea of how much you use on a typical fishing day.     Ultimately you will want a fuel flow meter or an NMEA networked fuel data system...   

[hurstian]

went to gas station yesterday, after one weeks use, I only filled 13 gallons, which surprised me, especially considering the tank may not be full to begin with.

[Diablo]

I installed a fuel gage and found it useless. I need to disconnect it because it will run down the battery if I procrastinate and do not plug the charger in.

[First Cabin]

I grew tired of trying to see the fuel level in my discolored tank.

Installed a WEMA fuel sender.  Since calibrating, it has been nuts on accurate from full to empty, even with the strange shaped tank.  I also installed a Garmin fuel flow meter.  I like having the remaining fuel displayed on the fish finder.

[sikoruk]

I've found the Garmin fuel flow sensor to be spot on and since having it have never wanted for the fuel gauge that I've never had. I also like being able to find the most economical cruise. We tend to go on long multi day trips on the boat in the PNW, sometimes getting fairly remote and so fuel economy is very important to us.

[neild]

This season my gauge has been acting wonky. Last time at the fuel dock it read 1/2 tank and I filled right to the spout. I always try not to fill the tank right to the top otherwise I smell the gas while bouncing over the waves.

Wiring looked fine so I pulled the sender. I have the simple hinged arm sender with a float on the end. The float is held in position on the wire arm with little washer "stops". The upper stop has slid up half the length of the rod. so the float was sliding up the rod instead of lifting it.

I should have replaced the stops with something better but I just used some pliers to score the rod so the stop wouldn't slide again. I hope this does the trick.

[hurstian]

I checked the connection of my fuel gauge yesterday. It looks strange. Both sender lines are connected to the center post together. I believe that will cause the gauge to display empty all the time. Not sure why it was setup that way, but that may never work. Seller told me gauge was working recently, but that's impossible by this connection. Do I miss something?

Maybe they're using something else for fuel consumption, like nmea200:).

[davidsea]

  I replaced my float/swing arm sender with a Wema, and have been impressed with it.  The only catch is, you have to order it in the correct length to reach the bottom of the tank, since it is a vertical probe and can't be bent to fit or otherwise adjusted.  I've been known to forget to reset my Floscan totalizer when I refuel, and the Wema is a good backup for stupid. 

If you need to troubleshoot a conventional gauge/sender combo, the diagram below shows what has been the BIA standard for many years.  On the sender, the center terminal is 'sender' to the gauge, and the side 'tab' terminal is ground.  On the gauge, the center terminal is ground (G), the (S) terminal is sender wire from the tank , and the (I) terminal is +12 volts switched (ignition).  Don't wire this to battery+, it will drain the battery over time.  If the gauge is illuminated, the (L) tab goes to +12V dash lights.
     If you need to test the sender itself, disconnect both the center (sender) wire and the ground.  Use a multimeter set to ohms, and measure across the two terminals.  As you move the float arm, the resistance should change smoothly from around 30 to 270 ohms. If it doesn't change, jumps around, or is way out of the normal range, throw it away and get a Wema - don't waste money  with a swing-arm replacement.

[Danno]

David, what Wema model and length did you buy? Did you have to remove the tank to remove the old float switch or install the new Wema? Is there a NMEA2000 unit available?

[davidsea]

     Danno:  I used a Wema SSL19 sensor -  SS is for 316 stainless steel, the '19' denotes tank depth.  The 48 gallon tanks used in 19-21' Arimas seem to bow out on the sides with age and lose a little depth.  Wema recommends 1" clearance between the bottom of the sensor and the tank bottom. To make sure you get the proper length, pull your existing sensor, measure from the top of the opening to the bottom of the tank, and subtract one inch. On the above 48 gallon variety, this will probably be either 18 or 19". The sensor is rigid and cannot be bent, so be sure to make your measurement STRAIGHT DOWN from the opening - the curvature at the bottom front of the tank will affect your measurement.  May not be the cheapest, but Fisheries Supply in Seattle stocks a wide variety of lengths, and will special order others.
   In my SR19, there was enough clearance to pull the old swing arm sensor and install the Wema without moving the tank.
   I am not aware of any tank sensor that speaks NMEA2000.   The Wema and other traditional varieties are a simple variable resistance which changes with fuel level.  Battery voltage goes through the fuel gauge - which is just a voltmeter marked with E to F instead of volts - then through the variable resistance to ground.   It wouldn't be particularly difficult to make a circuit to convert voltage to digital info, but would be troublesome to calibrate to an accurate readout of gallons.  Easiest would be a Empty to Full bargraph  display on the MFD.    Maybe one of the members has seen something like this?   

[Danno]

David,

I found this with a google search (I should have googled before asking you to search for it  ):

https://www.defender.com/category.jsp?id=2380010&path=-1%7C344%7C2028701

They have a unit that converts the resistive data from a conventional fuel sender unit and also have NMEA fuel sender units and NMEA fuel gages.  I wonder if the converter can still be used to tap the resistive signal while not affecting the signal to the conventional gage?

The NMEA fuel senders can be calibrated for odd shaped tanks like those in Arimas. That there is a cool bonus.

[davidsea]

   Looks like a very cool product for those using NMEA.  Would be interesting to see what the display looks like, digital gauge, bargraph, or??   Says it can be used in paralell with an analog gauge if desired.   Using this conversion still requires an accurate mechanical analog sender, so a Wema-style replacement in the tank would be a good start.  No amount of electronic wizardry can make up for a crappy input. 

[Markshoreline]

Fortunately, the tanks in my Arima are semi transparent.  However, my Garmin measures fuel flow and if I do my part by resetting the fuel on board at fill ups the unit shows remaining fuel.