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  1. #1
    Member
    Join Date
    Sep 2016
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    Spanway, WA.
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    98

    Poor gas mileage 2019 250 ProXS 4 stroke

    Ser# 2B643656
    Reading on the Nitro forum about gas mileage regarding a long tournament run. There was discussion about gallons per hour of run time, and miles per gallon. One post talked about 3.5 to 4 miles per gallon. I have a smart Guage on my boat and the best I have seen is 2.1 mpg. That's running 50mph and under, in light chop/ wind. Speed was varied along with rpms, and trim. So no exact rpms, but I feel the trim was used accordingly. The 2.1 was over 3 days, 50 miles, and 25gals. Mercury quickleen and care on board and always used. Motor has 40 plus hours on it, and seems to be running strong.

    Boat in a 2019 Nitro Z20 Pro with usually around a 1/2 tank of fuel and a full gear. Air temp was around 50 degrees on this last occasion. However since I've had the boat I have never exceeded 2mpg, except this last trip, and rarely run wide open for any kind of extended time.

    What is the consensus for average mileage on the 4 stroke 250? Is this something I should have looked at? If so what should be checked?

    Thanks Randy

  2. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,941
    #2
    Impossible to answer this question as there are literally dozens of variables involved.

    Even two buddies with two boats same year/model/engine on the same river are going to be different.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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  3. Member
    Join Date
    Aug 2021
    Location
    Seneca, SC
    Posts
    339
    #3
    Like Don said, there are so many variables. Just to get a ball park number, while the boat is cruising, can you call up the gph fuel flow on the Smart Craft gauge? (I have a 300R and it pulls about 5.8 - 6.1 gph at 3000 rpm and 28 - 29 mph depending on wind, water conditions and boat load. You mentioned you ran 50 mph most of the time, so you can check the gph fuel flow (probably around 15.7 gph at 5000 rpm). If your Smartcraft really said 15.7 gph, and your gps said 50mph, you can divide those 2 numbers and get around 3.1 mpg in the example I used. Let us know what your numbers work out to be? It would be normal for the cruising mpg to be much higher than the average mpg, just like a vehicle. If the fuel flow in gph is way higher (30% or more) than Mercury estimates for that rpm, Don would likely have some suggestions.