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kiwicraig

Adding Fuel Sensor to Lowrance Elite 7ti

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I run an old fibreglass half cabin.  The previous owner got rid of the traditional plastic fuel tank under the rear seat and installed a 100l metal tank in the footwell of the cabin. 

While this is quite handy it completely lacks any kind of fuel gauge.  Generally, I just keep it topped off and I am not going far enough to worry about it.  However, on longer trips or multiday stints where I have stayed on a house boat and used my boat as a fishing platform I have found that it very hard to judge how much fuel I have left.  I also have no visibility on how efficient (or not) my heavy-handed approach to the throttle is.

I recently replaced my sounder with a new Lowrance Elite 7ti and this has given me the opportunity to do something about this.  This leads me to my current project – installing a fuel flow sensor that can send data to the sounder.

The fuel flow sensor communicates with the sounder via a NMEA 2000 network.  On my old boat I don’t have a NMEA 2000 network so to make this work I need to set one up – so in this project I am going to establish a very simple NMEA 200 network and connect both the sounder and the fuel flow sensor to it.

The Components.

Shopping around I found a Lowrance NMEA 2000 starter kit that gives you the minimum you need to establish a small network and connect the sounder to it.  This basically consists of:

-          1x Backbone cable

-          1x NMEA power cable as the backbone needs to be powered independent of any devices

-          1x T-connector that gives you an output from the backbone

-          1x Cable to run from the T connector to the sounder

-          2x terminators (one male, one female) that go on either end of the NMEA backbone.

In order to add the fuel sensor in I found a kit that included the sensor with integrated cable and another T Connector.

From a NMEA perspective that is all you need to connect the two devices.  Once you have a NMEA network if you need to add other components in you should just need additional T connectors and cables off the backbone cable.

The fuel sensor has a few requirements:

1)      It needs to be mounted vertically

2)      It should be close to the tank

3)      There needs to be a filter between the tank and the sensor.

My existing fuel filter is towards the back of the boat, but I wanted to mount the fuel flow sensor in the cabin near the tank.  Rather than try to move the main fuel filter I decided to install a second, inline fuel filter between the tank and the sensor.

The Install.

The first thing I did was snip the tape and cable ties holding the current fuel line in place.  I then undid the hose clamp securing the line to the priming bulb and elevated the line to drain the fuel in it back into the tank.  I held a little container under it when I broke the connection to catch any fuel that leaked out and just tipped that back into the tank as well.

Next, I cut the fuel line and inserted the inline filter, taking care that the flow direction marked on the filter was correct. 

I then figured out where I wanted the fuel sensor, cut the line again and added in the sensor. 

After that I re-attached line to the priming bulb and tightened up all the hose clamps.  Wipe all the connections down before priming so you can see if there are any leaks.

Before proceeding with the networking I primed the motor and started it up to make sure that was working as expected.  The inline filter is clear and I could see fuel flowing through it.  I am sure the sound to money draining out of my wallet was imaginary. So far so good. 

Next, I connected the power cable to one of the T connectors and wired that into the fuse block at the helm.  I then connected two other T connectors to that one.  I put one either side, but it would not matter.  To complete the backbone I added one terminator on each end.

I connected the fuel sensor to one of the T connectors using the integrated NEMA cable and used the long cable that came with the starter kit to connect the sounder to the other T connector. 

Before tidying up the cabling I powered the sounder on and confirmed that I could see the fuel flow sensor listed as a device – which confirmed that the NMEA 2000 backbone was working as expected. 

I will still need to calibrate it when I next go out, but all up an easy addition to the boat and I look forward to getting it out on the water and seeing it in action.

NMEA Starter Kit.jpg

Fuel Sensor.jpg

Inline Filter.jpg

Filter flow.jpg

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I have never liked fuel gauges and electronics is not one of my strong points.

I have always just used a dip stick for large fuel tanks, very simple just measure up the stick to the full mark cut a groove in it then measure 1/2 way and both 1/4 and 3/4 marks and find somewhere to store stick.

Sooner or later electronic device will fail.

Frank

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7 hours ago, frankS said:

I have never liked fuel gauges and electronics is not one of my strong points.

I have always just used a dip stick for large fuel tanks, very simple just measure up the stick to the full mark cut a groove in it then measure 1/2 way and both 1/4 and 3/4 marks and find somewhere to store stick.

Sooner or later electronic device will fail.

Frank

What I wanted to understand was flow rate, not just fuel level.  

Having said that I agree that planning for failure is important.  I've added spare media for the inline filter and a splice for the fuel line to my little box of bits I keep on the boat.  If the fuel flow sensor fails then it's a couple of screws to remove it and put the splice in to connect the two sections of fuel line.

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Great write up @kiwicraig How did I miss this one? I'm getting ready to do the same so find your post was really good. I was looking for another post of yours so I'll look for that then add something to it

 

 

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On 8/22/2018 at 4:18 PM, kiwicraig said:

What I wanted to understand was flow rate, not just fuel level.  

Having said that I agree that planning for failure is important.  I've added spare media for the inline filter and a splice for the fuel line to my little box of bits I keep on the boat.  If the fuel flow sensor fails then it's a couple of screws to remove it and put the splice in to connect the two sections of fuel line.

Would love to know the outcome to this?  I need to upgrade my sounder and Id love to have some sort of fuel flow sensor

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My Yamaha gives km per litre, litres per hour etc direct to my Lowrance using nmea 2000. It's 100% accurate which is great for seeing directly on my screen where the best trim and rpm give the best economy.

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