Fuel economy- Mercruiser 4.3L

[joshl]

Just purchased an 1988 19' runabout w/ a 4.3L Mercuiser. After two weekends of cruising only, I am questioning the gas mileage. It runs great but, the best I can calculate, we are getting about 3 miles per gallon, cruising at around 4000rpm. I think that the carburetor I have is a single barrel and I have the mercruiser outdrive..

Can someone tell me how to gauge the fuel economy for this boat? or can someone tell me their experience with the same motor?

I am hoping to improve the fuel economy

 

[Phish555]

Re: Fuel economy- Mercruiser 4.3L

I believe the carb will be either a 2bbl, or a 4bbl. I have the same year, 19' runabout. Kind of hard to calculate "mpg" on the water. More like hpg. I think mine does really well in the economy dept.

 

[BAYLINER185]

Re: Fuel economy- Mercruiser 4.3L

I have an 07 4.3

Hers my Gas consumption....OK one day with my girl and her daughters and boyfriends a total of 6 people on board 1/2 tank of gas....HAULING *** all day....Like 4 ro 5 hours on the lake and problably a total of 1 hour running at WOT ( several racing around moments )( 4500~4800 ) I only burnt up about 1/4 to just about 1/8th before empty tank of gas..


Normally Ill put in 20 bucks the gauge will say 1/2 tank and if Im fishing we haul *** out and back and slowly cruse around for fishing spots. I can usually do two trips like this.

I think the 4.3 is really good on gas.....Mine is however an 07 model so compaired to an 88 who knows. Depends also on how well your motor is running.

My 7.4 is a gas eater if I try to run WOT on that all day. I WONT DO IT. My cruser is so not designed for runing at 45 MPH all day unless I have the cash to shell out to keep the tank full.. It does well around 3000 RPM all day however.

 

[Don S]

Re: Fuel economy- Mercruiser 4.3L

3 MPG is about average for your boat. Unlike a car, a boat depends a lot on boat weight, hull design, trim, rpm, wave conditions, current, wind, and really about anything that effects the water.
If you want to know the best rpm and speed to run your particular boat. you need something like a Floscan to monitor the fuel usage and then keep track of the info on YOUR boat.
http://www.floscan.com/html/blue/recreationalmarine.php

 

[45Auto]

Re: Fuel economy- Mercruiser 4.3L

A brand new carbed 4.3 in a 19' runabout gets about 4.5 MPG at 4000 RPM.

Somewhere around 3 MPG is probably reasonable for a 20 year old hull and carbed engine. The fuel injected 4.3's get .1 or .2 MPG more.

If you slow down to 2500 RPM or so you will probably get a little more mileage.

Not a whole lot you can do to improve mileage on a boat except get a lighter boat.

You can see the kind of mileage a new 4.3 gets here:

http://www.boattest.com/boats/1734/test_results.aspx