Yet another Yamaha Fuel Management Question....

Onewolf · 05-19-2005, 09:00 AM

My Yamaha fuel management gauge "fuel total" consistently reads ~17% high. For instance the FMG says that I've used 136.4 gallons and it takes only 117.0 gallons to fill the tanks. I've read the previous threads about the Yamaha Fuel Management gauge issues and I assume the problem is one of these issues (in no particular order):

1) Faulty sensors
2) Improper mounting of sensors
3) Air getting into the fuel line ahead of the sensors

Are there other things I should look for?

Another thing I've noticed is that the current GPH consumption rate bounces around rapidly at all speeds for both engines. At my normal cruising speeds the combined GPH will constantly jump around between 15 -- 24 GPH when running a constant speed. The FMG on my previous boats with Yamaha engines (0x66 engines) did not behave like this. Is this normal for Yamaha's big four stroke engines?

Finally, is it safe to assume that the 'realtime' GPH figure (ignoring all the bouncing around) is reading about 17% high since the fuel 'total' is consistently 17% high?

Thanks.

Doug

SIM · 05-19-2005, 10:11 AM

Add to your list: Faulty Gauge as well.

They should not jump around like that. When you run the FM system on one engine only.(P or S) on the display where it shows only one engines fuel usage, is one engine more consistent with its GPH reading or do they both individually jump around?

If its one engine then most likely there is a bad sensor. Swap that sensor with the other sensor and see if the reading issue goes with the sensor. If it does...then you know its a sensor.

If they both jump around then most likely its the gauge.

The total usage is based off of what the GPH reading is. If the GPH reading is high....then the total will be as well.

Maybe you can describe or post a pic of your FM fuel sender installation.

Andy