1st post - fuel consumption problem/question ...

[arizonasunbird]

I've got a 1991 Sunbird with a Mercruiser 3.0 4 cyl. Has a Holley 2 barrel carburetor. Yesterday it used 10 gallons of fuel running for 2 1/2 hours at about 3,000 RPM. Is this normal ? Seems like awfully poor mileage/hours for fuel consumption for the little 4 banger. Thanks for any insight.

Phil

 

[Bondo]

Re: 1st post - fuel consumption problem/question ...

I've got a 1991 Sunbird with a Mercruiser 3.0 4 cyl. Has a Holley 2 barrel carburetor. Yesterday it used 10 gallons of fuel running for 2 1/2 hours at about 3,000 RPM. Is this normal ? Seems like awfully poor mileage/hours for fuel consumption for the little 4 banger. Thanks for any insight.

Phil

Ayuh,... Welcome Aboard,... Merc never used a Holley carb on those motors, 'n I thought Sunbird used only OMC motors, 'n drives,...

But anyways,...
Figurin' yer doin' 'bout 30 mph at 3000 rpms, that's 7.5 miles per gallon, which Ain't bad, at All...

 

[HT32BSX115]

Re: 1st post - fuel consumption problem/question ...

Ayuh,... Welcome Aboard,... Merc never used a Holley carb on those motors, 'n I thought Sunbird used only OMC motors, 'n drives,...

But anyways,...
Figurin' yer doin' 'bout 30 mph at 3000 rpms, that's 7.5 miles per gallon, which Ain't bad, at All...

That's really good.

I have a fuel flow gage on my Liberator. At 30 MPH (and 3000 RPM), it flows 10gph. Or 3.0 MPG.

 

[arizonasunbird]

Re: 1st post - fuel consumption problem/question ...

Ayuh,... Welcome Aboard,... Merc never used a Holley carb on those motors, 'n I thought Sunbird used only OMC motors, 'n drives,...

But anyways,...
Figurin' yer doin' 'bout 30 mph at 3000 rpms, that's 7.5 miles per gallon, which Ain't bad, at All...

My bad....I stand corrected. Outdrive and engine are OMC. duh.....

phil

 

[Don S]

Re: 1st post - fuel consumption problem/question ...

My bad....I stand corrected. Outdrive and engine are OMC. duh.....

phil

And people wonder why we have problems answering questions. :facepalm:

 

[Bondo]

Re: 1st post - fuel consumption problem/question ...

And people wonder why we have problems answering questions. :facepalm:

Ayuh,... Go easy on 'im Don,...

He's got that Black paint Envy....

 

[arizonasunbird]

Re: 1st post - fuel consumption problem/question ...

I know, I know - wishin and hope'in won't make it a Merc.......

So the mileage, etc. seems ok for this boat ?

 

[jopes]

Re: 1st post - fuel consumption problem/question ...

eh people who buy boats typically don't worry about fuel millage.

 

[Scott Danforth]

Re: 1st post - fuel consumption problem/question ...

that is good boating fuel economy.

I usually go thru about 25 gallons in just over 3 hours

 

[HT32BSX115]

Re: 1st post - fuel consumption problem/question ...

I know, I know - wishin and hope'in won't make it a Merc.......

So the mileage, etc. seems ok for this boat ?

yeah. It doesn't make any difference whose name is on the drive......... a 3.0L engine is the same either way and they're VERY fuel efficient!

BUT, load that boat up with too many people, pull skiers, start/stop a lot, run it at WOT etc, and your fuel consumption will increase.

 

[QC]

Re: 1st post - fuel consumption problem/question ...

I am going to submit that 40 MPH max 17 - 18 footers are good on fuel no matter what the power plant. OB, I/O and any design, even 2 strokes. With the exception of jets, they all get around 4.5 - 5 MPG. Working on posting some good data to support this. Gonna take a while though. I don't believe there is anything about the 3.0s that make them the reason that these boats get good mileage. It's more about how much power it takes to propel a small runabout at 25 - 30 MPH and the amount of fuel that it takes to make that power. We are talking efficiency swings of 10% max between technologies, and then it is about weight and speed.

There just aren't any magic engines when the product is Stoich burn and 4 cycles. Especially not old, heavy and carb'd. The 3.0s are all three.

 

[HT32BSX115]

Re: 1st post - fuel consumption problem/question ...

It's more about how much power it takes to propel a small runabout at 25 - 30 MPH and the amount of fuel that it takes to make that power. We are talking efficiency swings of 10% max between technologies, and then it is about weight and speed.

You're absolutely right.


Several years ago I think Trailer Boats ran an article about similar boats with different engines..................

Specifically, Would a boat with a "Big Block" get far worse "mileage' than an identical boat with a smaller "Small Block" engine if they were operated at the same loads and speeds.

They found that both boats used approx the same fuel when loaded the same and ran (more or less) the same.

Which makes sense because most gasoline engines will exhibit approx the same Brake Specific Fuel Consumption. (BSFC)

 

[sam60]

Re: 1st post - fuel consumption problem/question ...

Hopefully I'm way off, but on my setup, after refueling and gps review of the trip, I estimated 1.8 MPG. I know we have way different engines and boats, but I would real happy to go 2-1/2 hours at 3000 RPM on 10 Gals. Keep going and enjoy!

 

[arizonasunbird]

Re: 1st post - fuel consumption problem/question ...

Thanks for all the good information and comments.
Just thought for some reason that my consumption seemed excessive.
One of the reasons I asked is that I ran out of fuel about seven miles from the marina and had to be towed.
But now I know for sure that I need a new fuel gauge sender and how far I can expect to go.

Live and learn........

pj