Installation of Fuel Flow Sensor

[lawndoctor]

I am considering adding a fuel flow indicator (probably one of the Navman or Lowrance units) which I understand would require a sensor to be installed in the standard flexible fuel line, positioned after the fuel filter.

From what I can tell, the fuel filter on my boat is attached to a plate that is mounted on the engine block, and all of the fuel line after the filter is metal.

Would the correct installation method be to find a way to install the sensor in the metal line, or should an additional filter be added to the system?

Thanks for your help.

 

[Lazy Daze]

Iwould require a sensor to be installed in the standard flexible fuel line, positioned after the fuel filter.

I've wondered that, too. Why can't it be put before the fuel filter? Is it just because the sensor should have filtered fuel? If so, then, yes, just put in another filter - Racor or something.

 

[PlayDate]

You need to check with Navman or Lowrance. You have an EFI engine and the placement of the sensor is dependent on the fuel line configuration.

On carb models, they recommend placement after the water separator and before the fuel pump which means for those installations it is before the fuel filter.

Some EFI have return lines for unused fuel. That means a much more expensive installation.

-John

 

[Tail Chaser 661]

I've wondered that, too. Why can't it be put before the fuel filter? Is it just because the sensor should have filtered fuel? If so, then, yes, just put in another filter - Racor or something.

That's it,
Needs to be filtered fuel.
Don't remember, After filter, I think before pump? NO pressure pump pulsation going into sender.
Fairly easy install already having rubber fuel hose on my boat.

Installing a Racor would be easier and better with today's bad fuels.
The install is a bit tricky.... Keep away from heat and vibration. Also have sensor/fuel going vertical so no air bubbles can get trapped in sensor giving in accurate readings.

 

[Daniel P Thomas]

John
I too have thought about doing the same modification.
My questionis are ther units out ther for older models such as mine?
1992 350 EB 450 7.4L Bravo II Carb Engines?

Thanks
Dan

 

[Tail Chaser 661]

John
I too have thought about doing the same modification.
My questionis are ther units out ther for older models such as mine?
1992 350 EB 450 7.4L Bravo II Carb Engines?

Thanks
Dan

I have the Norstar on my boat.
Designed for NOT having a return fuel line to tank.
Nice little unit for under 150.00
The 300.00 and up Flo Scans can tie into your GPS giving you MPG

 

[electricaldoctor]

Check with the manufacturer re: max. micron size for your filter. I am told that too many will affect the performance of flow sensor. Perhaps in the 30 micron size??

~Ken

 

[CJ Martin]

Before you do anything, check to see if your engine is Smartcraft enabled. My 2002 350 Mags were. Adding Smartcraft displays is fairly straightforward, will give you fuel burn (and a bunch of other stuff) and does not require cutting into the fuel system.

-CJ

 

[davefin]

I mounted my Navman system alongside the fuel tanks. Placed a NAPA 5339 inline filter just before the sensor on each side. I cleared this inline filter set up with SeaRay, Mercruiser and Navman before install. Works great. Although the Navman 3100 guage recently crapped out and needs to be replaced with the newer Northstar F310. Here is a pic of the port side install....

 

[PlayDate]

John
I too have thought about doing the same modification.
My questionis are ther units out ther for older models such as mine?
1992 350 EB 450 7.4L Bravo II Carb Engines?

Thanks
Dan

Dan,

The installation on carb based engines is very straightforward and generally a weekend project. Lowrance and Floscan make good units. Navman was purchased by Lowrance and hopefully they cleaned up the quality control problems Navman had with their Fuel computers.

I have worked with all three and like the information of the fuel computer and the information it provides. You can see the difference of a clean hull and how operating conditions affect fuel economy as well as determine the optimum rpm for cruise.

I also like the Floscan unit which provides an analog display of fuel consumption. It's sensors are very accurate. My only compliant about them is the sensors can crack if you overtighten the fittings.

Both types will serve you well.

-John

 

[davefin]

Just a clarification....Navman was purchased by Northstar in 2007. The Navman 3100 is now the Northstar F310.

 

[Lazy Daze]

That Northstar F210 that was mentioned above looks nice. Although, I would prefer an actual "needle" as you can see tendencies easier - like the Floscan. But, for the price, that Northstar looks awful good!

 

[lawndoctor]

Thanks for all of the input everyone.

My engine is not Smartcraft-capable. I would prefer to go with the Northstar 310 because it will accept NMEA 0183 input from my GPS (Lowrance is NMEA 2000) and I only want fuel flow and economy information (Floscan has tach and engine hours on the display).

Davefin: Is that NAPA part number complete? I tried searching the NAPA web site and it doesn't recognize that number.

I mounted my Navman system alongside the fuel tanks. Placed a NAPA 5339 inline filter just before the sensor on each side. I cleared this inline filter set up with SeaRay, Mercruiser and Navman before install. Works great. Although the Navman 3100 guage recently crapped out and needs to be replaced with the newer Northstar F310. Here is a pic of the port side install....

 

[trit21]

From my understanding as well...the smartcraft is based on the pulsations of the injectors and the fuel flow is an approximation of fuel used. Unlike the flue flow sensors (mentioned within this thread) which will be actual fuel that flowed out of the tank and the injectors.

I would think the fuel flow sensors is more accurate than the smartcrap....oops smartcraft.

 

[Lazy Daze]

Lawn, if you only want fuel info, wouldn't that Northstar 210 be good enough? It's a lot less money.

Question for you (a serious question): What does the NMEA input give you?

Floscan also makes an analog gauge that is just GPH - if you like the analog look. But it's also more $$.

 

[lawndoctor]

Lawn, if you only want fuel info, wouldn't that Northstar 210 be good enough? It's a lot less money.

Question for you (a serious question): What does the NMEA input give you?

Floscan also makes an analog gauge that is just GPH - if you like the analog look. But it's also more $$.

The way I figure it, if I go to this much trouble I want a unit that displays not only fuel flow, but also fuel economy (MPG). That can be based on speed over water (data sent from a paddle wheel sensor) or speed over land (data sent from a GPS unit). Given those two choices, I would prefer a unit that can use speed data from my existing chartplotter, which uses NMEA 0183.

The Lowrance units are NMEA 2000. The digital Floscan units show MPG, but they also show other stuff that I don't want. The Northstar 310 (formerly Navman 3100) accepts NMEA 0183 input, so it seems like the best option for me, even though some people have had reliability issues with it.

The main problem for me is the fuel filter issue, which seems like a major PIA, and is making me wonder if this project is really worth it.

 

[Lazy Daze]

Oh, OK. I see what you're saying, now.

Filter? Not that big of a deal. Just a buy a Racor fuel/water separator (or something similar), install it after the line comes out of the tank, install the sensor next. All before you get to the engine-mounted filter.

 

[lawndoctor]

Oh, OK. I see what you're saying, now.

Filter? Not that big of a deal. Just a buy a Racor fuel/water separator (or something similar), install it after the line comes out of the tank, install the sensor next. All before you get to the engine-mounted filter.

Thanks, I'm fine with performing the installation, but what concerns me is whether an extra filter will compromise fuel flow and engine performance. I called Mercruiser and they told me the only add-on filter setup they sell for my engine includes an additional booster pump that is needed to make up for the back pressure added by the extra filter. I have no interest in doing something like that. They would not recommend any other add-on filter for my engine. I'm waiting to hear back from Navman.

 

[Lazy Daze]

They would not recommend any other add-on filter for my engine.

They won't. Too worried about covering their own... you get the idea.:smt001

 

[Y Knot]

I installed the lowrance lmf-200 with the ep-60r fuel flow sensor on my engines. I added an inline fuel filter prior to the sensor and haven't had a problem with them. It took me about 2 hours to install the sensors and the gauge. Spending money to see how much money your spending on gas...LOL