Im having a huge problem with the new Mercury. First off its a 90 2 stroke on a 17' nitro. I filled the tank today before I went out and I ran approximately 25 miles roundtrip. I hold her at about 5400-5600 rpm steadily. I ran through 13-14 gallons of gas in this 25 miles..I don't understand? Anyone have any ideas or suggestion of why this has occured before I drop it off for repair? She runs good except some racket she makes at idle in gear (thats another issue).

Hmm

I used to run from Udahl boat dock on Norfolk lake in Arkansas to the dam and back, approximately 60 miles on 18 gallons of gas.  I was on fumes when I got back.  That was running a pretty steady 3300-3400 RPM's the whole way.  If I tried to run at WOT, around 5600 RPM's I could probably get to the dam (30 miles)  but would have to gas up.  Maximum fuel milage is usually seen in the 3000 rpm band not WOT like you were running, then the motor becomes a huge gas sucker.

As for your motor, you're expending about 2 gallons per mile at WOT.  I've seen some etec numbers that show them getting around 3 gallons per mile at WOT.  Check with you dealer on your numbers, you may or may not be off.

A generally accepted rule of thumb for fuel consumption for a two cycle outboard is 10% of the HP,in gallons, per hour a WOT. So your 90 HP outboard would consume 9 gallons per hour at WOT.

I run a 17'6" Sea Nymph with a 75HP Suzuki 2 stroke. Running 25 miles at WOT ( about 5200rpm) I'll use about 11 Gal

I also run a 17 foot Alumacraft with a 125 Merc 2 stroke. That same 25miles at WOT will use about 14 gal.

So what you are experiencing is the norm. When you run these outboard at that rpm they are gas hogs. there is nothing wrong with your motor

What has me concerned is that I have made this run many times over the last two weeks and I was eating up only around 7-8 gallons. I run it the same way each time the only difference may be if there is a passenger or not. Yesterday no passenger.

Thanks for the feedback on this, Im not near as worried about it as I was.