fuel hog Df140

[akmoosehauler]

My brand new DF140 is using more fuel then my old Sx150.
It is using the same or more fuel on all the same runs.
With the Sx150 i could go 38 miles on 6 gal gas, the 140 will use the same or more for the same run. If i run the 140 at 6,000 like i'm told i can watch the fuel in the tank go down very fast. Any thoughts out there? Thanks.

 

[Rancherlee]

Re: fuel hog Df140

what size boat and how fast does it run @ wot

Most DF140's I've seen use between 11-13 gallons per hour @ wot with should be around 6400rpm, if your at or below 6000rpm you could be lugging it and causing excessive fuel use.

 

[gss036]

Re: fuel hog Df140

Rule of thumb is to drop the "0" on the end of the HP and that will give you the GALLONS PER hOUR usage. It does not matter which engine you have, it just takes the same amount of gas to produce the high speed. The newer engines are much more efficient at low to mid range, but they are all the same at max RPM.

 

[akmoosehauler]

Re: fuel hog Df140

The boat is 22ft Pacific Skiff with a homemade cabin on it the est weight is 1500#. The boat goes 40 mph at 6200 rpm with a 23 pitch prop on it.
With the 21 pitch prop it would over rev at full throttle and the speed was not there plus the motor was just screaming with no go just noise.
I know how to judge the fuel use with the hp rating. I would have not bought this motor if i knew what it would use for fuel. Other boats as heavy or heavier get better fuel milage than me with the same motor only reason i bought this motor.If this keeps up i will rebuild the old motor. I have to turn almost 4,000 rpm to get the boat on step. With the old motor i could get up at 2,800 rpm.I ran the old motor at 3,200 rpm most of the time for the most mpg. Here in Bush Alaska we use our boats from April to October every day just like people use their cars so fuel mpg is important. So what gives with this motors mpg?

 

[gss036]

Re: fuel hog Df140

Something is not right on the set up. Is the leg the same length? Maybe raise the motor up a bit on the transom and trim it out. At 40000rpm I would think you would be doing 25-27 mph which should plane pretty easy. Look at the motor height and where the cavatition plate lines up with the bottom of the hull.
Make sure you are hauling around a bunch of water in the hull.

 

[tommays]

Re: fuel hog Df140

38 miles on 6 gal gas = 6.33 MPG



i have never seen any 150 HP motor get that kind of MPG ?


Tommays

 

[akmoosehauler]

Re: fuel hog Df140

Yes the old 1999 fuel injected Sx150 went 38 miles on 6 gal gas at 3200 rpm.
The new motors cavation plate is even with the bottom of the boat.
No extra weight of water. This is a fishing boat so I would see any water on the bottom of the boat and I have checked all the floataion voids.
With the Sx150 i could do 55 mph and get 5,500 lbs on step with it of course
it was using 15 gal hr to do it. The 140 just sound like it is screaming to
get any speed out of it. This motor is just getting me mad. I guess i'll have to step back and breath.

 

[steelespike]

Re: fuel hog Df140

Excuse my ignorance but isn't the SX150 a 6 cylinder 2 stroke and the DF140
a 4 cyl. 4 stroke.From my very limited observations it appears that while the
4 strokes do a little better on gph mpg can end up the same or less than a
2 stroke.Depending on the application and speed.
I assume the 4 cyl. is a smaller displacement than the 6.asked to push the same weight.

 

[akmoosehauler]

Re: fuel hog Df140

People with the same motor are pushing just as heavy or heavier boats are getting better gas mileage than me, just read what i have put down.
I know the motor is 10 hp down but what the heck it is using more fuel than the old motor it seams at all rpm's. The 140 is lighter than the Sx150 by at least 60 lbs.

 

[micel]

Re: fuel hog Df140

I would try to look at the positives,unless you can take it back.Its got a warranty,quieter,more dependable,more enviromentally friendly(some areas have banned 2-strokes)and 6.3mpg is actually pretty great.From my observations 4-strokes are great for trolling,you should notice a 50% decrease in fuel consumption at low rpm and 25% at midrange rpm.Woa they get basically the same fuel consumption.I would try royal-purple synthetic lubricants,some people claim a 10% increase in fuel consumption and able to go up 2" prop pitch.

 

[akmoosehauler]

Re: fuel hog Df140

Here another thing a relative with same make boat leangth and weighs about 400 lbs heaverier has a Yamaha 80 4-stroke carb gets better fuel mileage.
4-strokes put out just as much pollution as 2-strokes. Only at a idle is it quieter than my old motor.

 

[akmoosehauler]

Re: fuel hog Df140

It is still taking 4,000 rpm to get the boat on step. I have gone over every
connection and have done the 20 hr maintance. The oil had a funny look and
color to it. When i started the motor after the oil change it smoked on start up and the color was blue with black. Fuel use is still more than any other boat with the same motor. It is still bothering since our fuel price is $4.79 a gal. I have also installed a SeaSport tail on it with know better results.

 

[gotboostedvr6]

Re: fuel hog Df140

the cav plate should be slightly above the water line at speed. you will go faster this way and get better mpg.

a good rule of thumb is water rises 1/4"+ for every inch of setback off the hull at 60 mph or less .. the slower you go from 60 the more rise you get..

if your hull is 6-8" from the motor when its trimmed out for speed you can rase it 1.5-2" from the bottom of the hull and still be touching the cav plate. 2" higher or so then its mounted at now at now would get you optium speed and efficienty at under 50 or so mph..

also if you want efficienty you need to have a handheld gps and play with trim while watching rpm at 30 mph on my proline i can almost double my mpg by trimming up a decent amount. you will really need to play with your setup to get good results..

now that you have a hydrofoil installed you will undoutedly need to bring the motor up a bit
if you have any questions email me at gotboostedeg@gmail.com

 

[akmoosehauler]

Re: fuel hog Df140

I have tried playing with the trim of the motor, taken out any extra weight
nothing is helping the motor get better fuel economy. Even when i punch the throttle it takes a lot of rpm's to get on step. Other boats with 90 hp motors
that are on heavier boats get better mileage than mine. I am waiting till i have extra money to get the dignostic tool for this motor.

 

[Outsider]

Re: fuel hog Df140

Other boats with 90 hp motors that are on heavier boats get better mileage than mine.

And 6+ mpg doesn't cut it? I guess you just bought the wrong motor ...

 

[akmoosehauler]

Re: fuel hog Df140

This 140 does not get the fuel milage that my old motor got.
I cannot go 38 miles on 6 gal gas like the old motor.
The motor takes 4,000 rpm to get the boat on step.

 

[akmoosehauler]

Re: fuel hog Df140

Talked with the dealer about my motor today. the mechanic thinks it is the boat itself that is causeing more fuel use and that i should be able to cruise at 4200 to 4800 rpm. I know what a lugging motor sounds like since we run 2 stokes and 4 stokes here in bush Alaska like cars in lower 48. Have run them for over 20 years all type and sizes.

 

[gotboostedvr6]

Re: fuel hog Df140

you can modify the hull to meet your needs.... unfortunately it seems that you wouldn't want to do this nore do you want to adjust the motor height to suit your requirements for fuel usage. This being the case it seems that your just venting and we are wasting our time helping you.

Bring it to the dealer and have them fix it.