Fuel Flow Meters - Good or Bad?

[Guest]

Fuel gauges - we all know how they vary with the truth, so I installed a Navman Flow / burn meter last summer. It appeard to work okay for a couple of months and then indicated less and less burn etc until nothing on the clock but the makers name! So off it went back to the suppliers who returned it with compliments. Fantastic you say, how nice....without wishing to sound ungrateful, it now shows a variety of numbers at a variety of times. none of which are close to the truth !
I really only wanted it as an indication of fuel remaining.
Has anyone got a good experience of these that might indicate that they really do, do the job. It is currently on a Mercuiser 5.7 efi (no fuel return)
thank you.
Comments, if you would please.

 

[tcm]

I have one but have no clue how it works. It read 300,000 litres and range 3km. Or did this mean that it was very accurate?

seriously, I think these are indeed gizmos, in my humble opinion. - If you knew what the approximate range of the boat was, and how long you had been running, and the little weeny fuel guage is on red...you'd ignore the fuel flow meter if it said anything different. Same as on a car when the range says 0 miles, you creep home and take the wife's car next day...

 

[oldgit]

My fuel flow meter does nothing but indicate the amount of fuel going past it at a given moment.But is the finest way to persuade me to throttle back and reduce speed that I know of.It actually reads in litre per hour but a quick calculation into ££££££££££££................

 

[Guest]

thanks for the info..............I guess I shouldn't expect the same sort of accuracy on my boat as in my jumbo.......!

 

[Guest]

But does it vary in its readout at a steady throttle setting, that's what relly gets me...........

 

[oldgit]

Nah. just reads "Oh my god how much". All the time.................

 

[oldgit]

Re: REF Your jumbo Good or Bad?

I do hope it was not you that ran out of jet 1 the other day.How many tyres did he lose on landing!I wonder if he tried tapping the lcd always makes it work.Gulp.

 

[Guest]

I've got a Navman fitted to a Volvo 5.7Gsi DP (EFi). Over the past 2 years it has worked consistantly-except that it always under reads by 10%. Navman say it can only possibly be +2%!!.

I think its worth having, because I know the constant error.

 

[DepSol]

I found the Naman ok in the petrol boat I had but not that accurate.

I trust my fuel gauge and records kept and can predict very close to the litre how much I have in my tank. When I go to refill from the tanker they have a stop so if you say 300 litres it will stop on 300. I have a competition with the tanker driver every time to guess how much goes in. He doesnt tell me how far its got and i cut the lever as a little bit of fuel comes out of the overflow and have been consistantly within 1 to 5 litres from my guestimate. I know when I hit zero on my fuel gauge I have 38 litres in the tin.

Dom

 

[tcm]

Re: vary fuel flow with fixed throttle setting

That simply must be rubbish if the flow varies with fixed throttle setting. Only things i can think of would be

1) flow falls gently down, as cables don't hold properly
2) flow falls gently as engineroom warms up reducing inlet density ...err but this wd be simply density of air, not volume of fuel?
3) fuel meters are a bit crap.

 

[neale]

I have the Navman fitted to a 5ltr and have found it very useful for adjusting the throttle to acheive an ideal speed/fuel consumption situation. Mine overreads so I have a built in safety margin. The instructions recommend calibrating the meter and I understand that the more you do this, the more accurate it will become. If yours is just giving you nonsense readings, I suggest you send it back again.

Neale

 

[David2452]

Not sure about the navman but the Flowscan is very acurate after it has been correctly set up. Fluctuating readings are usually as a result of mounting the sensor to close to the fuel pump causing pulsing or pulling air in upstream of the sensor, neither of which would affect engine performance and would otherwise go unnoticed.

David

 

[Guest]

Hadn't thought of that. Have you got a fuel filter before the flow sensor?

 

[ArthurWood]

Re: Floscan

Hear good things about Floscan and am thinking of having them fitted to my gas guzzler.

 

[David2452]

Filter should be upstream and sealed with light grease on thr gasket as I found mine was pulling in bubbles of air and affecting the flow. If you go to the Flowscan site they have a useful trouble shooting prcess whic is also included in the fitting instructions. Although it is primarily designed to troubleshoot flowscan products many of the basics apply to any sensor.

David

 

[softop]

I have two Floscan units I fitted to my boat with 165 Volvo diesels after calibrating them they are better than 2% accurate. I had a couple of installation problems but the people at Merlin in Poole where I got them sorted them out very quickly. 01202 697979.