Excessive fuel use

[Brad R.]

I had a nice 4-day 4th of July weekend, but i noticed my newly purchased (third time ever driven) 22sx uses way more fuel then i expected. Roughly 60 gal in 8 to 9 hours of use. Thats about 7gph. This is with NO ballast, minimal cargo, 4 to 8 people, no towing, and no WOT, just easy cruising at 25mph. I cleaned my spark arrestor two months ago, the oil is new, and the engine ran perfect with no sign of needing a tune up or having bad fuel, other then the high fuel use. Any tips to help my economy; or lack there of. Is it even possible for this engine to run rich? What are your real world GPH numbers? Thanks.

[Ktown]

I don't normally track fuel consumption, but I did notice the manual has some data on what RPM has the best efficiency.  The RPM/Fuel burn curve is pretty normal until you get to about 4,000 RPM, then it goes up pretty quick.  So, I always cruise at just less than 4,000 RPM.  In fact, I try to pull folks out of the water at 4,000 RPM (which my boat does well).  Unfortunately, your cruising speed of 25 MPH, should be right at that number.  The data is on the engine page of the manual and this site.  4,000 RPM = 7.5 GPH.  I believe the associated speeds are for the non-V-Drive boats.  I hope this helps.

http://www.epicmarine.com/images/300i%20Specs1.jpg

[wakejunky]

My SX burns roughly 45 gallons in 9 hours. we usually have 4 adults and 1100 pounds of ballast. If i run over 30 mph it gets ugly but thats due to my wakeboard only prop. What prop are you running?

[Brad R.]

My prop is the Acme 3-blade model 515, 13x12 pitch. It has no top end speed, but is a monster out of the hole. I think the RPMs are around 4,000 to 4,300 at 25 MPH. I was unaware that the fuel economy took such a nose dive about 4,000 rpm. If i go much slower i'll barely be up on plane. Is my prop the main problem, and what should i switch to if so? I'm cleaning my MAF sensor as we speak. I'll try to keep it under 4,000 this weekend and see how it goes. Thanks guys.

[blindside]

Something isn't right.  I have the same prop and at 25 mph (no ballast) the rpm is at 2400.

[blindside]

I mean 3400 rpm. I wish 2400 lol

[Brad R.]

Maybe we have different gear ratios than each other. My top end speed is only about 36 mph, and that has the tach buried past 6000. Is there a rev limiter?

[wakejunky]

S-22 GEAR RATIO IS 1 TO 1.23

SX GEAR RATIO IS 1 TO 1.46

ill check my rpm's to speed next time im out. My top end speed is about 35/36 and im running a modified version of the 515.  same diameter and pitch but much bigger cup.

[Brad R.]

Ok, thanks. I'll also recheck my numbers tomorrow at the lake. I was just disappointed after hearing Epic owners talk about being out all weekend and barely moving the gas gauge, but when I go out i can barely go a couple hours without heading for gas. And the bank to take out a 2nd mortgage. 

[Brad R.]

Hey wakejunky, you said your prop is the same as mine and it's 'wakeboard only'. I assume i can get more top end speed and keep my rpm's down with any other prop. Any recommendations? Want to buy a spare 13x12? 

[Brad R.]

Ok, I checked my speed and RPMs. The acme 13x12 prop gives me 25 mph at 4100 rpm. My top speed is 37 at 6100 rpm. The boat easily and quickly passes the 6000 rpm mark and buries the needle. I want to switch props because i would prefer not to pass the redline so easily, and that the maximum speed was closer to 45. Plus the fuel use would be less since the RPMs are lower at cruising speed. The Acme 515 prop is great for a powerful hole-shot, but i feel like I'm stuck in first gear.

[wakejunky]

Brad R. - I've got the stock 13x13.5 4 blade and a 13x12.5 4 blade of the same brand. I'll trade you either one for your 515. I could always use a spare. Not quite the hole shot as my modified 515 but, better than going back 2 stock if i hit somethin.

[Brad R.]

Thanks for the offer wakejunky, but I also have the stock 4-blade as a spare. I think I will stick with the acme brand since they seem to be the most advanced in design and manufacturing. I want to see what the local shop will give me on trade, but i'll certainly keep your offer in mind if that doesn't work out. Thank you.