I'd like to add a fuel flow display to my 2003 Mercruiser 496 MAG HO.

I have a GPSMAP 546 chartplotter, so I think I could get the Garmin GFS-10 fuel flow sensor (https://buy.garmin.com/shop/shop.do?pID=11561) for $200

Alternatively I could get a SmartCraft gauge or NMEA 2000 converter like the MercMonitor, but it's quite a lot more expensive, but then I'd have a dedicated gauge and more engine data available.

Does anyone have any experience with either of these?

Thanks.

I think you are better of with the mercmonitor. The engine knows how much fuel it is using.

I went with the Smartcraft System Monitor. So far it has been very accurate and it gives me important data like water pump PSI, GPH, Gallons used, temp (which seems to be more accurate then my analog gauge), etc. Found it on Ebay for $90 with a cable and the monitor (used obviously).

i cant imagine the GPS would be all to accurate and the engine would know more.

I think they have a device out now that integrates the Smartcraft system with the NMEA system.

I have a Garmin unit that can hook up, but what I'd really like is just a simple dash-mounted gague that would show

speed
fuel useage
RPM

That's pretty much it, and I could do without the speed indicator.

+1

So does the merc monitor; work with the mercrusier 496 engines?

Yes, it's working beautifully with my 2003 Mercruiser 496 and Garmin 546.

NMEA engine data is transfered from the MercMonitor to Garmin, and GPS data is transfered from the Garmin to MercMonitor.

FYI I got mine from europeanmarine.org. If you email them with your specific situation they'll put together a kit with everything you need.

The reason i was asking is that, i'm considering going to the 496ho for repower..and wanted to add this feature for more dash input..what type of data would i get from either of the two mentioned above, because i dont have the room for the big display units on dash..and what is the size of the merc monitor unit

The garmin specs show it must be mounted inline, and uses 3/8 barbs. Not sure of the fuel line size on the 496HO, but wouldn't it be bigger than 3/8?