I have twin Yamaha 115s on a Grady White. Last summer I hit some debris that was in the ship channel and after that my speedometer stopped working and my total fuel consumption is now only showing half of my total consumption.I fixed the speed by cleaning out the debris in the water sensor at the bottom of the motors that are used to track water flow. However not sure if this will also fix the fuel consumption since I have no way of testing until I get the boat back in the water. I think it is still showing the correct gallons/hr usage for both motors.1. Could fixing the speedometer have fixed my total fuel consumption measurement? I was thinking total fuel was calculated just on fuel flow and not with speed.2. Any way to test the fuel flow gauges that are on the fuel lines?3. Any ideas of what could be wrong?These are the Yamaha Fuel Management system. The motors are 2001 models.Appreciate any help!
Hi,Speed input is only needed to calculate liter(or gal)/nautical mile (fuel economy). Without speed input You get only liter(gal)/hour.Must be something else that is wrong. Do You use a water/fuel separator on the fuel line before the fuelflow sensor ("wheel")? Maybe You should have the fuelflow sensors checked - maybe You have "debris" in the sensors or maybe You just need new sensors? How many hours on them? On my Navman 3100 a recalibration should be performed after 100 hour and after 5000 liters of fuel the fuel flow sensor itself should be replaced. Maybe similar for Yamaha Fuel flow sensor? Have You "calibrated" the fuel guage? Not sure it is needed on a Yamaha Fuel Management Guage system but Navman Fuel (2100 or 3100) needs at least 20 liter but more is better (or corresponding gal) as a "known" amount fuel to use and then set that fuel used in the guage. First you set the guage to 0 used and then use the exact known amount fuel and when all is used you set fuel used to that amount. Then the guage is calibrated based on that used fuel. Without doing so the readings will be as much as 10% wrong (calibrated just a few % error). That is the way it is done with a Navman fuel guage, not sure about the procedure for Yamaha Fuel Management Guage - check the instructions.Do You have a GPS? Try to interface your Yamaha Fuel Management Guage with that instead if it support that type of interface for speed input - it will be more accurate. Usually NMEA out on GPS connects to NMEA in on the Fuel Managment Guage. I use GPS as speed input on my Navman 3100 fuel management guage so I get the fuel economy displayed - nautical mile/liter(gal), not liter(gal)/nautical mile as Yamaha guage shows as fuel economy.I use a Yamaha F115.Do You have this Yamaha Fuel Management Guage? http://www.yamaha-motor.com/accessor...25/detail.aspx It has support for GPS input as speed source for calculating fuel economy.(that Yamaha guage for dual outboards is rather expensive by the way... $1,096.95)
if your taking the distance traveled information from your speedo tofeed tothe fuel management gauge then yes it should workagain. yes the unit can be calibrated but you have to use a known amount of fuel with either a watch or a GPS. also one tach, the speedo and the fuel management ga must be on the same key on power source. I see it all the time with 2 on one key and two on the other. if its wired like that it wont work correctly. if the speedo does not work how will the management gauge get a distance data reading? unless your interfacing it with a GPS for speed/distance data. its a good system but has to have all correct inputs for a correct output. garbage in = garbage out.
no tech questions by PM, they wont get answered.
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