Fuel economy of a Blown Big Block

[TERRYCLARK]

Why does my 24ft pontoon with a 75 Mariner get such terrible mileage? Dealer I bought it from said the carbs had been rebuilt. Anything I can do to improve the mileage, or is this normal for a boat this size?

Thanx

 

[Chris1956]

Re: Fuel economy of a Blown Big Block

Well, it would be helpful to know what you mean by terrible mileage. That motor can burn 7.5 Gal of fuel, per hour at full throttle. Partial throttle would be more like 4 gal/hour. What are you seeing. What is the max HP rating for the 'toon?

 

[TERRYCLARK]

Re: Fuel economy of a Blown Big Block

I'm getting about half that at part throttle. Don't know the max HP rating, tag is worn. It's a Ercoa with the flat toons.

 

[QC]

Re: Fuel economy of a Blown Big Block

"Half" what? If you are only burning 2 gallons per hour at anything more than 6 MPH, then you should be very happy. I think you are missing the GPH vs. MPG thing. What numbers can you confidently give us?

Edit: Just found a 'toon with a 75 Merc that is burning 9 GPH at WOT. Boattest.com Suntracker Bassbuggy 18

 

[TERRYCLARK]

Re: Fuel economy of a Blown Big Block

I mean I'm getting half the economy. I went 16 miles at part throttle and used 6 gal. If I ran full throttle my 6 gal. tank wouldn't last 30 min.

 

[redjmp]

Re: Fuel economy of a Blown Big Block

Just under 3 mpg sounds about right for that boat...
Try running it around 3000 rpm for best economy...

 

[Jlawsen]

Re: Fuel economy of a Blown Big Block

OK. so you went 16 miles on 6 gals and at full throttle you think you'd burn 6 gals in 30 minutes. So at part throttle you went about 16 miles in an hour and you're using 6 gph. That's not all that bad. A 6 gal tank on a toon is probably a lot less than I would go out with. You might want to invest in a couple of more.

 

[QC]

Re: Fuel economy of a Blown Big Block

Yep. 3 MPG. That's what most of us expect, even from v-hull runabouts. Agree, 6 Gallon tank with a 75 is REALLY small.

 

[TERRYCLARK]

Re: Fuel economy of a Blown Big Block

REALLY small ! ! That's all the boat had when I bought it, I added a 12 gal. I have only had it out twice. Just wasn't sure if the fuel cosumption was normal...........now I know. Thanx for the replies.

 

[KRS62]

Re: Fuel economy of a Blown Big Block

You might want to research a different prop. This opens up a ton of other questions, but having too low a pitch prop will eat more fuel than a higher pitch prop....IF you go the same speed.

KRS

 

[Faztbullet]

Re: Fuel economy of a Blown Big Block

Boat is way under powered with a 75hp.

 

[TERRYCLARK]

Re: Fuel economy of a Blown Big Block

......I've got to live with it right now! If I put a around 100hp on it would it use less fuel or just push it better?