Fuel Monitoring Systems

Thinking of installing a fuel sensor on your boat? Before you begin, here are 11 pointers from the pros.

“Save the planet” has been a tagline since the beginning of the modern environmental movement over 30 years ago. Now, more than ever, the push is on to go green, not only to preserve the natural beauty that draws so many to boating in the first place, but also to “save your wallet” from today’s rising fuel prices.

Fuel monitoring systems or fuel flow meters can increase a boat’s effective range by accurately recording total fuel consumed and pinpointing optimum speed. This will help you construct a fuel/speed curve for your particular vessel. You can use this chart to determine your boat’s sweet spot, rather than try to figure it out from the engine manufacturer’s published information.

Installing a fuel sensor with an NMEA 2000 backbone is a project any boat owner can complete; however, before you attempt it, here are a few pointers and tips that we have used throughout our many installations.

1. Most importantly, due to the volatile nature of gasoline’s low flash point, you must always be aware of the hazards involved in working around it, and take proper precautions in order to protect the safety of yourself and others.
2. If you are not able to safely remove the fuel line from the engine compartment, reduce spillage by installing the sensor to a high point in the line.
3. If you have two fuel outlets on one fuel tank, always make sure to install the sensor after any Y or T in the line feeding the engine.
4. A fuel filter should be inserted between the gas tank(s) and the sensor. Your sensor is sensitive and must be protected from contaminated fuel.
5. Having additional filters, hoses and cable clamps on board is a good practice as mechanical services are not always readily available while cruising in the Pacific Northwest.
6. Garmin and Lowrance units are limited to use with gasoline only. If you are running diesel, which has both a feed and return line, you may want to consider FloScan. They manufacture sensors for both diesel and gasoline engines.

NMEA 2000

Networking your system with an NMEA 2000 is a huge advantage over systems of the past as an N2K network allows a boat owner to add N2K devices without resorting to running new connections between each sensor and display. N2K networks allow the boater the simplicity of plug-and-play. Herein, I will discuss some pointers for a simple N2K network with a few nodes.

1. Ideally you’ll want to insert the power for your N2K system in the middle between the final node and its connection at your display. Powering your N2K system from one end limits the power available at the other.
2. The fuel sensor and the display are not termination points for your N2K system. You must use a terminator resistor at both ends of your N2K bus.
3. N2K cables have a male and a female end. Make sure to use the proper end that corresponds with each connection.
4. Plan a route for your N2K system that will allow room for future growth. Down the road you may want to add a tank level sensor, battery monitor and so on.
5. Don’t be afraid to cut. Though not desirable, sometimes the connection point of your N2K cable is too big to fit through a crowded conduit. An N2K field service connector can be used to connect your cut cable.

Displaying the wealth of information from your fuel flow sensor through N2K is plug-and-play with a multi-function display. However, this information can be buried in sub-menus and may not be readily available. I suggest considering a dedicated data instrument, such as the Garmin GMI 10 or the Lowrance LMF-200 and LMF-400. These devices are simple to navigate and can display data such as fuel usage, level monitoring, engine data, depth and more.

It is exciting to witness the level of systems monitoring technology being integrated into marine vessels. I tell my clients that the addition of a fuel sensor and an N2K backbone is a great jumping off point, opening up a world of future expansion, with many great new N2K-enabled products being developed every day.

About the author: Jeff is the owner of Pacific Yacht Systems, a full service shop delivering marine electrical and navigation solutions for recreational boats. This is a new series of columns on the changing world of technology and boating.