I recently installed Simrad fuel flow sensors on both engines (325 Aft Cabin with 350 XL Crusaders), and took her out for the first time this season. On both the out and back, I had the port engine report using about 9.7 gallons of gas each way, while the starboard only reported about 3.5 gallons used each way. It'll be easy enough to conclusively prove this next time I fill up, but I'm about 98% certain that the starboard sensor was WAY off. The 9.7 gallons definitely seemed right for the distance and throttle I was at. And unless the tachometer, throttles, and my ears were all deceiving me, both engines were running at the same speed. Certainly not enough difference to only be sipping a third the amount of gas.

Next time I'm at the boat, I will be double-checking to make sure the sensor is pointing vertically as instructed, and I didn't do something stupid like install it backwards. But does anyone else have experience with these sensors (or others like it) to know if they can simply be that far off in terms of initial calibration? It's a rather simple matter to recalibrate it when I fill it up next time. But my concern is that it's so far off right now, that it might be a fundamental issue with the sensor, and no calibration will will make it better. Although the fact that it recorded nearly the same amount of gas used both coming and going seems to indicate that it's at least consistently inaccurate now.