200hp Merc Outboard only getting 1.2 mpg??

jbl_91762

I've posted enough I should edit this section
Sep 23, 2017
268
118
50
CHINO
Name
JOEY
Boat
KAYAK
Whats going on with my fuel consumption gents. Had the boat since June this year so I finally got to learn that my fuel consumption is total crap at 1.2 mpg. I dont know exactly what motor is on there cause the mount plate SN pulls up a non fuel injected motor as it shows its a 2005 according to my local mercury repair shop. However It is an EFI model (Im very mechanically inclined I know its FI as I cleaned the VST and injectors) and I would say its a Blackmax model (pics of Max on motor)but google cant find what the last years were made. Boat is a 2001 22' Cape Craft center console with 75 gallon tank and about a 60 gallon bait tank (dry claimed weight is around 2600lbs). Went out with a full tank, full bait and 3 200lb adults for what the GPS shows a trip of 38 miles. My rough guess is I spent 20% of that 38 miles at 5mph, 70% at 1/2 and 3/4 throttle and 10% at idle. Was out on water for about 6 hours and I probably turned off outboard a total of 1 hour that time. Running a 3 blade 15 pitch SS prop. Motor runs great after fixing a few minor things, I was told by dealer that motor claimed to have under 500 hours. Both fuel/water separators have been replaced along with new fuel lines. I drained the entire plastic tank just to make sure It was clean and saw only very little sediment and yes fresh fuel with additives. FYI the stamp on motor block is 0G319446.
Everything I've researched on this site and other forums says people are getting 2.5 mpg if you keep it at 3/4 throttle or less. I cant stomach a repower just yet as I have to pay this boat purchase off hopefully by end of next year. Thanks for feedback and advice.
 

ShadBurke

I've posted enough I should edit this section
Oct 28, 2005
3,606
1,945
Carlsbad
Name
Shad Burke
Boat
22' Boston Whaler Guardians
Proper fill both times for correct gallons used?

Correct prop hitting WOT mfg range? Proper engine mount height? Fins, foils, trim tabs?

What is your cruise rpm and speed?

Hull bottom clean and not obstructed?

Mpg seems on the low side but questions....
 
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af dreamer

I've posted enough I should edit this section
Apr 16, 2007
4,534
2,151
long beach,ca
Name
tom
Boat
44 luhrs dreamer
My 21 Outrage with 200 Verado at 7KT troll gets 1.3 MPG,at 4000 and 25 MPH it gets 2.2 MPG.This is by the Merc gauges.The 2.2 has been confirmed on runs at cruise and back from Cat with no trolling involved.One person,95 gal fuel on board and a 25 gal bait tank.FWIW,Tom
 
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jbl_91762

I've posted enough I should edit this section
Sep 23, 2017
268
118
50
CHINO
Name
JOEY
Boat
KAYAK
Proper fill both times for correct gallons used? Yes topped off both times, my trip on GPS showed 38 miles and topped off again and it took 29 gallons.

Correct prop hitting WOT mfg range? Yes, WOT if 6200 for MFG and I believe I was around 5800 WOT for the brief period. Proper engine mount height? Yes Fins, foils, trim tabs? Yes

What is your cruise rpm and speed? 28mph and around 4500

Hull bottom clean and not obstructed? Trailered boat very clean

Mpg seems on the low side but questions....
 

ShadBurke

I've posted enough I should edit this section
Oct 28, 2005
3,606
1,945
Carlsbad
Name
Shad Burke
Boat
22' Boston Whaler Guardians
The 4,500 rpm cruise number @ 28 mph isn't helping you.

Slower is cheaper but for some, time is money.......
 

mike garrahan

TheSabreGuy
Sep 7, 2007
1,931
1,872
la habra hts
Name
mike garrahan
Boat
23 ft. crestliner
We have a 175 BlackMax on a 23' Crestliner and we never get more than 2MPG and that is when the water is smooth. If conditions are rough we are lucky to get 1.5MPG. The BlackMax motors run strong but they really suck the fuel.
 

MATTANZA

old man of the sea, in training.
Aug 23, 2004
5,513
2,998
Cali the state of confusion, the state of shock
Name
RICK
Boat
Boston Whaler 25' Outrage "MATTANZA II", 34' Radovcich "AMY ANNE" {when it needs to be fixed}
my whaler gets about 2.2 mpg @ 22kts, 3500 rpm. get a fuel flow meter to find your sweet spot on fuel economy. I have a smart gauge that tells me how many gph i'm burning, and I can tell how trimming the motor and different rpms effect fuel economy.
 

Mr Lingcod

I've posted enough I should edit this section
Mar 20, 2017
111
46
Santa Barbara
Name
Jesse
Boat
The Last Soviet
Try splitting the cost with your friends! Most friends love to split the cost because they love going out. That's the best way to make the cost (not the burn) less of a killer.
 

newmar

I've posted enough I should edit this section
Jun 10, 2005
104
10
68
spring valley
Name
bruce
Boat
23 blackman /Polkboat
The right prop versus the wrong prop can be half a mile a gallon.
Rig a flow scan and then borrow/rent five or six propellers large-diameter stainless steel ones.3 blades 4blades everything that you can find and then go make some notes
run the boat with all the weight that you would normally have on a fishing trip. and check mileage at various trim positions and engine RPMs trim tabs as well can change mileage. M at first make sure that you're seeing 55 to 5800 RPM at wot, slightly trimmed. If not then change to a prop that get you to that RPM. Then evaluate
For mpg.