Is there a way to measure fuel flow on a diesel engine?

salar

salar

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I have a Yanmar 4LHA which has no electrickery so no black box with NMEA2000 and all that. Is there a way of measuring diesel fuel consumption dynamically without spending a four figure sum on a fuel flow meter more suited to a much larger vessel? I appreciate that petrol flow is much easier to measure.
 
Fluid flow measurement is always difficult, especially relatively low rates of flow, requiring accurate measurement.

With a diesel it is more complicated because it is fuel in and spill return, and the rate of flow varies with several factors, so even a cheap flowmeter can't be fudged to give a reliable reading using an offset. Accurate readings require two meters and a method of summing the difference accurately.

I figured nearly a years fuel cost did not warrant this extra knowledge as the payback would never be achieved, instead simply assessing usage by qty used each fill over log miles and / or run hours, is about as good as it gets.

If you learn a method of doing this with reasonable accuracy for less than a few hundred quid please tell me before you Patent it.

Floscan for twin engine set up $3,060 plus shipping & install - ouch !
 
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On your dash you will see a lever, pushing it forward makes fuel disapear quickly, pulling it back lessens the effect. Always top up when finished for the day, this will assist in the sums re consumption, and keep the bug away. LOL
 
With Mechanical engines Floscan will measure Fuel burn rate .

http://www.floscan.com/html/blue/dieselmodels.php

Not cheap especially if twin installation.

I have a Hart Tank Tender system:

http://www.floscan.com/html/blue/dieselmodels.php

Also see
http://www.thetanktender.com/

I measure after every trip, I have calibrated my tanks ( each 1253 litres ) by emptying and filling 50 litres and measuring and then plotting a graph.

When I refill my tank I can tell to within 15 litres how much to take.

I then keep a log of fuel used after every trip against my " Boat's Log" which is through the water (not GPS which is over the ground and ignores tidal flow) and note destination speed etc.

This gives me a very accurate fuel burn rate use a reasonably high average burn rate and don't expect to use more than 80% of your fuel to keep a safety margin, works for me.

This is the third boat of mine I have fitted a Hart Tank Tender to, the same instrument can measure two diesel tanks, fresh water tank and black tank, no electrics all on air pressure.
 
One could try intercepting the fuel plumbing at the tank with simple 'Y valves' and connect the unused ports to a calibrated fuel container with a breather. Using a stopwatch and the other usual onboard parameters one can extrapolate all manner of statistics from 'T' equals nought.

The only problem is how to accurately measure the quantity of fuel used for a given time when the vessel may not be level or steady. May be a simple gimbel for the container or for a one off graph plot when you change the valve back to main tank, return at your leisure to terra firma and measure contents accurately!

I might add that this suggestion hasn't been approved by known authorities so without a solid engineering background you may be happier to have your suggestion approved as appropriate. Whatever and given the cost of instruments which seems to be the issue here, for the sake of a few bits and bobs collecting dust in the workshop, I'm sure salar will have quite abit of fun in the process and all in the name of messing about in boats for next to nothing! Or am I missing something?
 
Navman used to do a diesel fuel consumption set up; using a flow sensor on the feed and on the return. They became Northstar, but there seems to be some association with Lowrance later. The petrol Navman unit was very accurate indeed relating to fuel consumption ( my own experience based on something like 1,000 litres of fuel used was that it was within 0.1% or so !), I doubt the diesel one would have been any different.
 
It is possible to buy small 1" BSP fitting turbine type fuel flow meters from either ebay or other hydraulic component suppliers. Some for as little as £50 a unit. Down side is that you will have to fit it in line between tank and fuel pump. You will be able to accurately measure fuel uptake for each trip but unless you're related to Mr Heath Robinson you won't be able to see real time conumption.
 
but most diesel engines have a return to tank so some of the fuel passing out of the tank through the fuel pump will be returned - cheapest method - calibrated tank dipstick.
 
GrahamHR said:
Navman used to do a diesel fuel consumption set up; using a flow sensor on the feed and on the return. They became Northstar, but there seems to be some association with Lowrance later. The petrol Navman unit was very accurate indeed relating to fuel consumption ( my own experience based on something like 1,000 litres of fuel used was that it was within 0.1% or so !), I doubt the diesel one would have been any different.
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The diesel one was a pain in the ars. When it worked it was brilliant but the volumetric senders were delicate, became bunged up with the slightest thing, were position and vibration sensitive and the whole system would occasionally just not work for no apparent reason.

Plastimo quietly dropped it after many complaints. It's a shame because when it worked it provided useful info as it could connect to other Nav gear to give accurate real time mpg as well as burn rate and get accurate fuel levels

DSC00199.jpg
 
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Whitelighter said:
The diesel one was a pain in the ars. When it worked it was brilliant but the volumetric senders were delicate, became bunged up with the slightest thing, were position and vibration sensitive and the whole system would occasionally just not work for no apparent reason.

Plastimo quietly dropped it after many complaints. It's a shame because when it worked it provided useful info as it could connect to other Nav gear to give accurate real time mpg as well as burn rate and get accurate fuel levels


DSC00199.jpg
Click to expand...

Strange, the petrol version used the same flow sensors and I never had a single operational problem in around 8 seasons use , it was connected to a 5600 plotter. I fitted the sensor quite securely to the boat as recommended, rather than leaving it free standing held only in place by the fuel hoses. I did break the first sender after the first season, my fault. due to my own clumsiness when trying to change an impellor; the potting compound was very brittle and the cable broke when I deflected it close to the sender. I secured the replacement's cable to the fuel hose; no further issues. The impellor on the damaged one was quite big, it would have taken quite a big lump to block it; maybe more of an issue with diesel than petrol.
 
They are different sensors.

No impellers on the diesel ones - they are a sort of comical shell shape and measure flow with volume rather than flow rate. I don't know exactly how they work but there weren't impellors. I too secured them to the boat. A lot of issues were caused by a faulty sensor which navman replaced. There were other issues with the head unit as well which was a bit delicate software wise.

A good system but much more complicated for diesel and I think that's a reason it was dropped
 
Whitelighter said:
They are different sensors.

No impellers on the diesel ones - they are a sort of comical shell shape and measure flow with volume rather than flow rate. I don't know exactly how they work but there weren't impellors. I too secured them to the boat. A lot of issues were caused by a faulty sensor which navman replaced. There were other issues with the head unit as well which was a bit delicate software wise.

A good system but much more complicated for diesel and I think that's a reason it was dropped
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When I bought the replacement sender, they were quoting the same part number for the diesel kit, but 2 required not 1 ! I also fitted a filter before the sender as recommended.
 
I've seen a setup on a motorsailer, where a Tigerloop de-aerator designed to alter domestic heating oil setups from two to one string eliminated the need for fuel return flow. That allowed for an inexpensive flow monitor (Faria, if memory serves.)

http://www.tigerloop.co.uk/
 
My D4 EVC equipped boat has a fuel consumption read out on the tachometer, along with other readings. The problem is that the LCD display is so faint, even at maximum legibility level, that in sunlight and underway it and any other parameters are effectively illegible. Shame really.
 
GrahamHR said:
My D4 EVC equipped boat has a fuel consumption read out on the tachometer, along with other readings. The problem is that the LCD display is so faint, even at maximum legibility level, that in sunlight and underway it and any other parameters are effectively illegible. Shame really.
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Will the Volvo stuff interface with a MFD so can be displayed there?
 
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