Fuel burn question.

[CHANCE1234]

thanks Zak. Heres why i ask. i installed a brand new 49 gal fuel tank and sender this winter. left barnstable harbor 2 weeks ago with just over 3/4 tank and steamed to ptown to fish which is roughly 16 miles. once there we just idled and drifted for the most part. 16 miles home to barnstable. gauge read, about an 1/8th at the pier. yesterday, i wanted to fill it up again and was only able to put 17 gallons in before it came out the vent and burped out the fill twice.

got u/w last night and guage read between 1/2 and 3/4. 15 miles at cruising speed and again idiling around looking for fish. than back at the pier last night read 1/2 tank.

assuming that when i left the first time i had about 36 gallons. when i returned by gauge told me that i had about 6 gallons left. should i have burned 30 gallons during that ptown trip? or is it more likely i only burned 17 gallons which is all the tank allowed me to put in yesterday before my night trip? thanks for any help.

[gofastsandman]

My guage is way off at anything but displacement speed. Just under full on plane can read just under half. Trolling against the stream here, I can see negative mpg on some days. Crazy, I know.