I have a 1990 Searay 220cc cubby...

[Rico1]

I have a 1990 Searay 220cc cubby cabin with a 454, 7.4l engine. This thing will go through a full tank, 40 gals, in a day on the lake. Can anyone give me some help and or ideas as to how I can reduce this consumption. Short of replacing the motor. I'm disabled and a cancer survivor, so don't have much ability to do very much on my own. But I damn sure do give it my best shot. Thank you in advance. 

Richard

[Sky]

You can change your props you can add fuel injection

[gayleforce]

i would not add the fuel injection but ensure that the card is not over feeding.

[jr_schantz]

A V8 motor uses fuel...end of story. Not much you can do to conserve other than turn off the key or reduce rpm. If you're tubing, skiing, or running at a high rpm, it's going to use a bunch of fuel. Expect to use somewhere around 17 gph at 3500 rpm. At 4000 rpm, you'll go through the 40 gallons in a couple hours.

Here's a site that has a fuel usage calculator.
http://www.boat-fuel-economy.com/mercury-mercruiser-3.0-181-fuel-consumption-us-gallons

[fwebster]

7.4 Merc's are very sensitive to being out of tune. Pay attention to all tune up specs and in particular, change your plugs and plug wires if they are several years old. Merc ignition wires break down quickly and will arc to the engine. The more of that you have going on, the less intense your spark at the plug gap will be. To compensate, you advance the throttle and increase fuel burn.

The most efficient rpm's for a 4 bbl 7.4 is about 3200 rpm or just before where the secondaries open up, exceed that and your fuel burn can get up to 36-38 GPH; stay below 3200 and your economy gets a lot better.

[dick]

I agree with fwebster. You might also check the distributor housing to make sure you don't have corrosion. .

[Deja_Blu]

Make sure prop is in good condition and is pitched for economy and not performance. Comment on secondaries is spot on.

[Rico1]

I would like to thank everyone for their input on my "fuel consumption " matter. I just recently found out that the prop on the boat is not of the same "specs" as when it was originally made. As a matter of fact, it looks that I'm "4" pitches too high currently. Will try to obtain a prop closers to manufacture specs and post results. Again, thanks for everyone's input.

[jr_schantz]

The prop is a big contributor. Your goal should be to find the diameter and pitch that provides the maximum recommended rpm for your motor at wide open throttle. Everything else is a result of achieving that performance metric.

[Big_Ed]

Hi I once had a 95 220 Cuddy with that 4:54 and what you need to do is listen for the secondaries on your carburetor. well it would definitely help changing that propeller back to stock but listen to the secondaries on your carburetor with a 4 barrel you run a secondary wide open you increase your consumption. I like to cruise my current boat around 3600 RPM.