Fuel flow meter

F

Fishcatcher907

New member
Who has installed a nmea compatible flow meter for a carbureted Honda on their boat?
I just picked up a 2005 with a Honda 90 (4 carb engine) and it looks to be kind of a gas guzzler. The setup is wrong. I need to work on some different combinations and would like to get accurate data.
Which flow meter did you buy. I’m installing a new 9” echo map plus that’s nmea 2000 Compatible and I figured I would give it a try.
 
I have used the Garmin, the Lowrance (Simrad), and RayMarine. Almost any of them will work fine with the Honda 90---no fuel flow data with the carburated engines. The Honda 90 is pretty much the standard on most of the 22's. It is possible that the engine is mounted too far down. Also trimming the bow down too much can be an issue, especially if there is no chop.

All of the above rely on NMEA 2000 networks. So you have to choose the one which is related to your instruments. (MFD) Maretron also makes a fuel flow sensor. The cheapest stand alone will probably be the Lowrance EP60 with LMF 200 and a MNEA 2000 backbone. Best if you can add a sensor to your own multi function display (MFD). I have run all three major manufactures and they are all about the same.

FlowScan used to be a stand alone--but they seem to be out of business--although there is a repair facility. There is a web site still up. Also pricey.

I believe that Marco Flamingo has a Digiflow meter, which installs in the line, and not expensive. However I believe it may not have remote readout.
 
I have the Lowrance LMF-200 and EP-60R sensor. It works fine. Like was mentioned, you'll need a NMEA 2000 network to use it. A network backbone and associated wiring is about $100.

If you want the LMF-200 to compute range and mpg you'll also need a NMEA 2000 compatible GPS system.

If you have a NMEA 2000 network and a modern chartplotter, you may only need the fuel flow sensor. You can find them for ~$160.

The only issue I have with the Lowrance FF system is that if it is on and the voltage sags too low during an engine start, all the settings and data get lost. If the unit is switched off during a start this does not happen. The manual suggests wiring it into the ignition switch, but I found having a separate power switch works better. I switch the system off before starting the engine.

Newer Honda engines (e.g. BF100) are NMEA compatible now.
 
Ssobol brings up a good point about low battery voltage and any electronics. I run the electronics on the house battery. With a Voltage sensitive relay (VSR) between the engine start battery, and the house battery, there will be no voltage drop. The two batteries are isolated at the time of engine start, but when the engine battery reaches 13.6 or so volts, the batteries combine, and then the house battery charges off the engine alternator. The electronics are protected. Many years ago I lost a very expensive set of instruments due to voltage spikes during engine start--every since I have isolated electronics from starting battery.
 
I have a Faria (no longer made). I bought an inexpensive Digiflow (<$50), but never installed it because I found a NOS Faria unit on Ebay. I've been impressed with the Faria's ability to accurately compute overall usage. For real time usage, it jumps around a bit and I have to mentally average the immediate usage rate. For instance, when on plane it might waiver between 4.5 and 4.8 mpg, with an occasional seemingly random 4.3 or 5.0 reading for a second. A more expensive unit may contain an algorithm to smooth out those readings. That might be beneficial or simply give one a false sense of accuracy.

The benefit for me is an alarm that goes off at 5 gallons remaining and an accuracy over the entire tank usage (23 gallons) within 2/10ths of a gallon. Much better than watching my analog needle waive back and forth from empty to one half full. Plus, it can be switched to liters when in Canada.

The Faria unit sold new for about $200. It would be hard to recoup that by using it to gain maximum efficiency on a CD 16. If using it allowed me to increase my overall rate from 7.1 to 7.3 mpg, it would still take me 50 years to pay for the gauge. For me, knowing that I have 7.2 gallons left in the tank is the reason that I love it.

Mark
 
On some (all?) fuel injected engines the fuel flow from the tank to the engine is not constant. This is most noticeable a low speeds where the FF may alternate between zero and some value regularly even while the engine is running smoothly.

The computed MPG can be affected by this from time to time and also if the speed is GPS based, there can be variations in the computed speed based on the quality of the GPS solution.
 
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