Anglers running older outboards and other kinds of engines can check the manufacturer's website for gauge and MFD compatibility, or buy an aftermarket fuel-flow meter such as those made by FloScan Instrument Co. (www.floscan.com).
FloScan sells products for gas and diesel engines from 25 hp all the way up to 6,000 hp, ranging in price from about $290 to more than $4,000, says sales manager Joe Dydasco.
FloScan uses a turbine or paddle-wheel sensor installed in the fuel line, like a filter, to directly measure how much fuel flows to the engine. The sensor generates pulse signals using opto-electronics: An LED light beam points directly at a photo transistor. As the rotor within the sensor spins, it interrupts the light beam and generates a pulse.
Pulses travel through the system's wiring to a meter at the helm. Meters vary in cost and capability. The simplest meter reports gallons per hour and total gallons consumed, while the more expensive 9000 series reports all kinds of engine information and connects to a GPS using NMEA 0183 to display mpg.
Dydasco says most boaters with gas-powered engines install their fuel-flow meter themselves; typically that involves three wires - 12-volt, ground and signal. However, diesel installations prove more complex as diesels come with forward and return fuel lines, which might be too physically rigid. Custom hoses might be necessary.
(Note: Garmin and Lowrance sell inexpensive NMEA 2000 flow sensors for older gas engines that don't transmit flow data.)
After installation, fuel-flow meters can also help diagnose engine trouble. "Once you've used our product, you'll know your engines burn 'x' gallons at 'y' rpm. If you see any drastic change to the normal gph burn rate, you'll know something's not going right," Dydasco says.
Of course, engine trouble also shows quickly in performance, but when it doesn't, a meter acts as a bellwether.
Dollars and Sense
Regardless of where gas and diesel prices float, fuel efficiency makes sense. Anglers should factor in fuel monitoring, just as they consider trolling speeds and line choices.
The technology is here: Upgrade gauges, add a meter, connect your engine to an MFD, or completely replace an older outboard and its systems. You'll certainly recoup some of that cost at the fuel pumps.