Mercury Jet M2 Fuel Return Line?

[Todd Pope]

Hi,

I would like to attach a GFS10 Garmin fuel flow sensor to my Utopia 185, and connect it through the NMEA2000 network to my GPSMap536S.

The specs for the GFS10 state that it will not work with a fuel injected engine that has a fuel return line, makes sense as the fuel flow would be overstated.

Does anyone know if the 240M2 has such a configuration? I have looked at the engine but it does not seem obvious to me.

Thanks

 

[K Rock]

The return line doesn't feed back to the fuel tank. From the fuel rail it is cycled back into the vapor separator through the pressure regulator.

Main pump
Water separator
Vapor separator tank
Electronic pump
Fuel rail
Pressure regulator
Vapor separator tank

 

[Dr Honda]

As above... the Mer engine isn't (really) a returning system. BUT... there is a return from the rail, that goes back into the vapor tank. You could attach it there... but I don't know how it will figure out fuel consumption based on the return.

If you have a "Newer" engine... it has a fuel consumption based on the smart gauge system.

 

[K Rock]

Doc, the sensor won't work if the fuel system has a return of any type. If it reads 4 gallons in, but 3 get returned to the tank it still thinks you used 4 gallons.

I wonder however, if he could still make it work. Being the vapor tank has a float, wouldn't that regulate inital fuel in? If that's the case, wouldn't he be able to get a correct reading on the line from the fuel tank?

 

[Dr Honda]

.........

I wonder however, if he could still make it work. Being the vapor tank has a float, wouldn't that regulate inital fuel in? If that's the case, wouldn't he be able to get a correct reading on the line from the fuel tank?

That's the way I would see it working. Watch the fuel in, since it's all gets consumed.

 

[Skibo]

Agreed - the fuel out of the tank is what you want to measure - that send/return cycle at the engine won't matter.

 

[Todd Pope]

Thank you all for your suggestions, the engine is a 2001 so I don't think it has a smart gauge system.

So if the sensor is inline with the fuel line coming from the tank it would register all the fuel flowing to the engine, anything that is "recycled" will be done so after the sensor so it should still be an accurate measurement, makes sense.