Fuel Management Glitch

[reelserious]

Was out fishing a few days ago about 50 miles offshore. The boat is a 2000 Sailfish with twin 200 HPDI's, which I have owned since new. Given the distance we were traveling, I decided to dial in the MPG's to optimize fuel usage for the conditions. The fuel management system is the factory installed with Yamaha gauges, where you can read GPH as well as gallons used, engine sync and MPG. The gauges would display GPH and the other gauge read MPH. When I switched to read MPG all I got was 0.0, which tells me that whatever "does the math" in the system (computer chip?) to calculate MPG was not functioning. I am assuming that the gauge itself contains the chip, but don't know if this is in fact true. I have a call in to my mechanic and will probably hear back tomorrow, but was curious if anyone else here has ever seen this and has any insight into what the fix is (new gauge, new chip...other?)

Thanks.....John

 

[ocnslr]

I believe the fuel management, by default, uses the pitot tube speed from one of the engines. This often gets clogged and reads zero. When that happens, the fuel management will also read zero mpg.

You can set up the fuel management to use GPS speed, but then you need to make an NMEA0183 connection to a small wire set on the back of the fuel management gauge.

Or, clean out the pitot tube.

Brian

 

[reelserious]

Brian,

Thanks for the response, but if you reread the above you will see that I was getting GPH and MPG, so the issue has nothing to do with the pickup tube..... nice try though

 

[reelserious]

Heard back from my mechanic. Turns out the chip is in the gauge. Sounds like the fix is a new gauge. He thought the gauge was around $600. I will find out tomorrow.