My MPG readout does not work-Yamaha FMS

[Gary M]

Bringing my boat home from the G-W dealer after servicing, I noticed that the mpg readout on the Yamaha Fuel Man System gauge was reading 0 and the rest of the gauges and all other info reads correctly.

Any ideas on how I can get that working again?

Thanks...........

 

[fishingstories]

are you running it? i dont usually get mpg readings until i enter the total gallons in tank then hook it up to the gps. when i run it, then it automatically calculates it for me. you might have trashin the bulb. try squeezing the bulb to free up any trash and see if things go back to normal. if not, then you have a problem with a sender wire or power or ground. oh, i have a lowrance fuel gauge not a yamaha like your so, i might be totally off. hope that helps.

 

[Gary M]

It's always worked fine until after I got it back from the dealer and I noticed it reading "0" on the boat ride home. Speed readout comes from the GPS at all times......

 

[Gary M]

Update.......

On the next trip away from the dock, it still read "0"......a mile later, it started working correctly again!!

A mile after that, it was back to "0" and stayed that way the remainer of the 4-hour ride.......

Any ideas???

 

[dduflo]

I have twin F225 Yamahas and there are two small sensors, one for each motor, that are mounted in the fuel line between the filter and the engine. One of mine quit working so I had readings the were half of what they should have been. Boat was new so Dealer replaced the faulty one. I was told that there is a mini paddle wheel that spins as the fuel flows thru. Maybe it has some gunk caught in it? I'd disconnect the fuel line on both sides and gently blow it out with an air compresser.

 

[Gary M]

I get a total fuel flow that is correct and my MPH/speed is correct coming off the GPS, but it's the computation "readout" on the FMS that is intermittent.....

 

[saltypup]

Gary,
Are you reading speed on your yamaha guages -- not the gps but the yamaha guage.
There is a tiny hole in the bullet of your ox-66's, you obviously have twins so only one motor will be provide the info. You'll have to pull the cover and look for which motor has the tube that runs to your guages. This measures speed through the water, the yamaha fms then combines that speed with the fuel burn to give you mpg. The system needs both speed and fuel burn to give you MPG.
If your already reading speed, MPH or KPH, then this is obviously not your problem but if your not reading speed on yami guage then there is a myriad of issues starting with a plugged hole or disconnected tube that will cause this.
I have the same year boat, engines and problem that you had including MPG not working after service that you are having.
Chris

 

[saltypup]

Sorry I reread your posts and see you have answered some of this already. Are you sure your gps is tied into the Yami guages. Yami absolutely will do this but typically i have found that they (yamaha fms) were rigged to the the bullet hole

 

[Gary M]

Are you sure your gps is tied into the Yami guages. Yami absolutely will do this but typically i have found that they (yamaha fms) were rigged to the the bullet hole

Yes, it gets it's speed info off the GPS. I had the Grady dealer make that mod when I bought it. It's always worked perfectly up until a few months ago.... I like it because I can tweak the trim and rpm to get max mpg.....