Whats the average mpg on a 20hp 4stroke outboard

Can't seem to get a clear answer online about how many MPG a 20hp 4stroke outboard would get at wot.I want to run a 6 gallon tank and i'm trying to fig out what i would average for a full tank.Also will a 20hp efi really get alot better milage then the carbed 4stroke?

Depending on how much the boat weights, you should get somewhere between 3 to 7 mpg @ wot.

Just put 1 gallon of gas in the tank and run it at wot until it quits.

Just make sure to take extra gas! LoL

That sounds like a plan,or i can go with a half of a gallon so it runs out faster.Then just do the math after that.I'm contemplating whether to go with a 6 or 9 gallon tank.

Boat is 190-200lbs
Me 270ish give or take a few lbs,lol.
friend 215lbs
motor would be either 115lbs or 97lbs turning a 10pitch prop.Wot 6300rpm.
Gear,cooler say 50-100lbs

You can just fill your tank to a point - run it a trip or two and then use your GPS to see haw many mile you have gone and how much gas it takes to fill the tank to the same point.

I had a 6 gallon tank and never seemed to have to fill up. I switched to a 3 gallon which allowed me to put it under the console moving some weight forward.

i have a 6 gal that came with my 30 efi. too big, physically. bought a 3 gal. never come close to running dry on a 1 day trip. i take a 2.5 gal can when i go camping. in reality u never run the big motor all day. my batteries for the tm are what controls my day. i pondered the 20 hp. efi sold me. 1 gal per 10 hp at wot seems to be the rule

There is a guy on you tube who said at wot he burns near 1.3 gallons per hr with the 15hp suzuki so i would fig with the 20 it's probally a hair higher at 1.5 to maybe 1.7 gph.I have heard that the rule of thumb is whatever the hp is take the first 2 numbers and thats what it is.So in that case if i have a 20hp then it should burn no more then 2 gallons per hr i hope.If i go with the 4stroke it's def going to be the suzuki but my options are still open to a really nice 15 to 25hp 2stroke merc or yamaha if i can find one for a decent deal.I have found a few but the price was insane.

I found a guy with a nice decent mid 80's 15hp 2stroke merc but he wants $1500, i emailed him to see if he would drop the price because it's been for sale for over a yr now and that should tell him something,his price is way,way to high.At best the motor is worth maybe $800-$1000.The motor is over 20yrs old i told him,he said he will let it sit till he gets $1500,i said ok good luck with that.He will own that forever unless he drops his price.Some people on cl think that when you buy a new outboard and then decide to sell it say 3mths later they can get what they paid for it,i hear all the time,it's brand new but it's been run for 6mths,i say huh.Thats not brand new,maybe close to new as you can get but not brand new.

Thats why i'm leaning towards a brand new one,the prices people are asking for most used outboards is insane,i'm not buying an older used one either i have had nothing but bad luck with them,i do all the good stuff,check compression,lower unit oil,make sure the motor works properly,then take it out and wham everytime something goes wrong,i would rather have a good new dependable outboard.I have had good success with merc,yamaha and honda,evinrude and johnson not so much,but to their defense i got a bunch of them when i was younger and didn't really know a thing about motors.The biggest problem i have had with johnson and evinrude is gas leaking out of the carb,almost every one i have had,that was the problem,or not turning over,carb gunked up very easy.I have bought tons of older mercs and yamahas and never seem to have that issue ever,maybe just my luck.

Stay away from the mid 80's 25 mercs. The carbs are junk and parts are hard to find for the carbs. Late 80's and newer are fine.