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Stainzy69hallett

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Fuel efficiency
« on: September 02, 2023, 07:08:49 AM »
I KNOW! I shouldn't worry about fuel efficiency if I'm ripping a bbc jetboat, but i burned right  through 40 gallons in a day and was kind of taking it easy. Im firing on all cylinders. I was just wondering if everyone else is burning right through fuel or if i have a problem somewhere. Would a efi throttle body help at all? I've got a 650 edelbrock with an electric fuel pump on top of a bbc 405 right now. My pump set up is a little odd but I don't ever feel like its sucking air. Has anyone figured out how to get a little more miles to the gallon? Any tips or tricks anyone wants to share would be greatly appreciated!!!

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75 fantasy

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Re: Fuel efficiency
« Reply #1 on: September 02, 2023, 12:10:32 PM »
I wonder if it?s because of the jet placement. Does it get on plane easily?


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Stainzy69hallett

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Re: Fuel efficiency
« Reply #2 on: September 03, 2023, 09:27:50 AM »
Ya it gets right up on plane. I plan on setting the pump back this winter even though this set up seems to be doing just fine. I mainly want to set the pump and motor back because ide like more room in the boat.

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Stainzy69hallett

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Re: Fuel efficiency
« Reply #3 on: September 03, 2023, 09:33:47 AM »
And I guess there is a ton of grey area on why I could be getting bad fuel efficiency, but my motor is running like a champ! I went through 40 gallons in about 4 1/2 hours of drive time. Is anyone going through that much fuel in that short of time? Is there anything I can do to get  better efficiency?

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75 fantasy

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Re: Fuel efficiency
« Reply #4 on: September 03, 2023, 05:53:02 PM »
It?s been a while since I had my jet boat but I do remember watching the fuel gauge lower as I romped around.


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96Laveycraft21Xt

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Re: Fuel efficiency
« Reply #5 on: September 05, 2023, 09:04:40 AM »
No, that seems excessive.  Are you just playing around and pulling tubes, skiers etc.?  we figure roughly 3 miles per gallon with all of our big block jet boats.  Combination Lake and river.  We cruise 3400 - 3800 rpms on average and always at least a few full throttles roosts along the ride lol


In my 4000 jet boat, i can boat all over Havasu, up river to the sandbar, pirate cove etc and i figure about about 20 gallons a day.  i would say thats a good 3.5 to 4 hours of run time per day
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Re: Fuel efficiency
« Reply #6 on: September 05, 2023, 09:31:13 AM »
Quote from: Stainzy69hallett on September 02, 2023, 07:08:49 AM
I KNOW! I shouldn't worry about fuel efficiency if I'm ripping a bbc jetboat, but i burned right  through 40 gallons in a day and was kind of taking it easy. Im firing on all cylinders. I was just wondering if everyone else is burning right through fuel or if i have a problem somewhere. Would a efi throttle body help at all? I've got a 650 edelbrock with an electric fuel pump on top of a bbc 405 right now. My pump set up is a little odd but I don't ever feel like its sucking air. Has anyone figured out how to get a little more miles to the gallon? Any tips or tricks anyone wants to share would be greatly appreciated!!!

Sent from my SM-S916U using SoCal Jet Boats mobile app

What impeller do you have? And how long has it been since a refresh on the pump?
Larger impellers tend to get better fuel efficiency.
As does a tight pump.
Even with a SBC, I run an A cut impeller.

Food for thought.

Dan'l
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Stainzy69hallett

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Re: Fuel efficiency
« Reply #7 on: September 10, 2023, 04:49:48 PM »
Ya we are just sking and playing around on the tube. I'm not sure what impeller I'm running. How do I tell what impeller I have? My pump hasnt been freshened up in probably 13 years lol maybe that's my problem. Should I run an A cut impeller? My motor is right at 348hp 380trq.

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Re: Fuel efficiency
« Reply #8 on: September 11, 2023, 04:38:14 PM »
It sounds like A impeller territory.
I'd first check the wear ring to skirt clearance.
Some can be measured through the clean out inspection hole.
If it's waaay out, then pull the pump apart, inspect the impeller, and you can also see what size the impeller is.
Feeler gauges for checking the gap.
My last one was .050 per side, or .100 total.
Ideally, .012 per side o r.025 total is factory spec.

Dan'l
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