Question on fuel level gauges--R27 OB

sd1209 · Jan 24, 2025

Just took possession of a 2018 R27 OB, 300 Yamaha with a 9.9 Yamaha ....NW Edition...appears well taken care of, low hours and surveyed well....Will keep it in the water in San Diego, Sunroad marina....Been reading this site for 6 mos now and excited to finally take delivery...
Question-----Running it today from Mission Bay to San Diego Bay I had the engine instruments display on the MFD and of course the Yamaha engine display screen off to the right side... ...The Yamaha screen showed a bar graph with about 3/4 tank of fuel.....The MFD display, with the engine instruments displayed, shows 2 fuel tanks...One lower left, one lower right on the screen and labelled tank 1 and tank 2......The lower left was shaded red, low fuel alert....The one on the right was 3/4 full......Took about an hour to make the trip, cruising about 25mph......I got 2 low fuel alarms on the MFD and each time the remaining fuel was lower.....Once 20 gals left, once 15 gals left......

So-----Is one of the tanks on the MFD display for the Webasto furnace (diesel) and one for the OB?? Is the Yamaha display to the far right (not the MFD) correct showing 3/4 tank left?? If the left display on the MFD is for the furnace, why was the fuel level decreasing?? I was not running the furnace.....Just confused ref which tank on the MFD shows what...Won't get back to the boat for over a week and when I get back I will fill the gas tank but thought I'd get input from the group ....

Submariner · Jan 24, 2025

sd1209 said:
Just took possession of a 2018 R27 OB, 300 Yamaha with a 9.9 Yamaha ....NW Edition...appears well taken care of, low hours and surveyed well....Will keep it in the water in San Diego, Sunroad marina....Been reading this site for 6 mos now and excited to finally take delivery...
Question-----Running it today from Mission Bay to San Diego Bay I had the engine instruments display on the MFD and of course the Yamaha engine display screen off to the right side... ...The Yamaha screen showed a bar graph with about 3/4 tank of fuel.....The MFD display, with the engine instruments displayed, shows 2 fuel tanks...One lower left, one lower right on the screen and labelled tank 1 and tank 2......The lower left was shaded red, low fuel alert....The one on the right was 3/4 full......Took about an hour to make the trip, cruising about 25mph......I got 2 low fuel alarms on the MFD and each time the remaining fuel was lower.....Once 20 gals left, once 15 gals left......

So-----Is one of the tanks on the MFD display for the Webasto furnace (diesel) and one for the OB?? Is the Yamaha display to the far right (not the MFD) correct showing 3/4 tank left?? If the left display on the MFD is for the furnace, why was the fuel level decreasing?? I was not running the furnace.....Just confused ref which tank on the MFD shows what...Won't get back to the boat for over a week and when I get back I will fill the gas tank but thought I'd get input from the group ....

The boat, stock, from the factory, has a single 147 gallon fuel tank. We round up and call it 150 gallons. Every time I fill up my tank, I have to go into the MFD and tell it "Fill up all tanks", which is just the 1 tank. The Chartplotter is usually really accurate on fuel consumption. For me, it's within 1 gallon. So, if the MFD says I have 47 gallons left, I'll put in 103 gallons at the fuel dock. The kicker, however, will skew the number though, as its fuel consumption bypasses the chartplotter. It'll burn 1gph at WOT. I don't rely on the Yamaha fuel gauge as it's a float and varies with my driving, in the waves, etc... It's a good back up gauge.

The Webasto diesel tank is 5 gallons, it's located behind the stove/oven. It takes diesel. I run Kerosene through mine as we use ours quite a bit. A stock 2018 model won't have a fuel gauge for the Webasto diesel heater. 2021 and new models do come with a fuel gauge (in the cave) for the diesel heater. The gauge is stand-alone and doesn't integrate with the chartplotter. It's a Webasto Airtop ST or STC 2000 heater. Webasto says to expect 1 gallon of diesel to burn over 20 hours. We boat in the Pacific Northwest and generally fill up our diesel tank twice a year. Sometimes 3 times a year. In 2023 we took our R27-OB to Glacier Bay. We spent the entire month of June in SE Alaska. We burned 8 gallons of kerosene in 4 weeks. (It was chilly!).

We have a ton of information all about the R27-OB published on our website and YouTube channel "Lets go channel surfing".

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