I am currently outfitting a sled and purchased a new 70 horse suziki pump. It is a 4 stroke and my question is about how much fuel does an E.F.I. use. I am going to have a fuel tank made and want it to be able to hold enough gas to last 2 good fishing days like 16 hours of drive time.
I am thinking it will consume approx 1 gallon per hour at 5,000 rmps. I could be way off ??????

At 5000 RPM, I should think you will burn a lot more than 1 GPH. You might get 1 GPH at 3000 RPM.

My 135 HP 4-stroke I/O burned about 5 GPH at 3800 RPM. Not sure how well you can compare I/O prop vs. OB jet, but I'm guessing that considering the HP alone would be somewhat valid. On that basis, I would estimate that you will burn 2 GPH at 4000 RPM, and 3-4 GPH at 5000 RPM.

I'm sure someone out there has real-world experience with a rig more similar to yours, though.

Regards.

Finegrain
Woodinville

I'd suggest sizing your tank with an emphasis on weight and ballancing your boat. Placement is also a critical factor. If you do it right your boat will handle much easier when free drifting and when on plane.

I would talk to who you purchased it from. They might get you in the ball park. Their are alot of factors that determine GPH. Weight of your boat, type of motor, driver. You can get a cheap GPH meter for about $300.00 But you probably only really use it once to find your cruising speed. The consumption of my motor 200 merc 2 stroke carb. is about 15 gph at full throttle. Thats about 52 mph. I have 85 gallons of fuel onboard. So if I am doing the math correct. I should be able to go full throtle for 5 hours and that will get me 250 miles from where I started. Now where the heck is it ever going to be that smooth. Their isn't any place i go that far away. Becides I usually run about 15 -30 minutes on the big motor then I run the 15hp honda for the next 8 hours. I cant even begin to do the math how long that honda would run on 85 gallons of fuel. I would follow erik instructions and balance out the boat. I would make it as large as possible without making it transom heavy or bow heavy.

If I was going to have a tank made and didn't know how big to make it I would hookup my motor to a 6 gallon portable tank and go try it.

Run it around the RPM's that you choose and go from there. Seems pretty easy to me!

Don't have a tank, go borrow one. Then you know.

fp