0x66 fuel burn please advise

[The_Chain]

Hey guys I have a 92 explorer with a hard top etc and Im running a 2000 0x66 250 what should I be expecting as far a fuel burn? mpg would be nice. I have two fuel tanks the 92 g and a 50 g i believe...I just wanna get a number there abouts on what I should expect to burn. I ran on my buddies 24 cc this weekend 180 miles round trip and wanna know if I am cutting it to close...is it time for me to think about the newer hpdi's since the 4 strokes are two heavy, what are they getting for a burn rate?

 

[family affair]

A poorly maintained ox66 will drink like a 21 year old frat boy at an open bar. A well maintained (and running correctly) ox66 will sip fuel as reasonably or better than a 4 stroke Yamaha at cruise despite what all the manufacturer's marketing brainwashers will tell you (they all now work for Ford promoting Eco -Boost. Yes, I own one and no it isn't as efficient as advertised.) Low speed the ox66 is not as efficient, but not terribly different.

You should see about 2.5 MPG at 30 MPH. If I were you I would either instal an aftermarket flow meter or test with a 5 gallon can before the trip. Our ox66 was a heavy drinker with few symptoms. Now that the bugs are worked out, it sips fuel and oil.
Good luck!

 

[grady33]

I just sold a boat with 2000 Yam 225s OX66s. If the O2 sensors haven't been replaced, they are due! Even if you test them and they check out fine, they can still have problems and cause poor fuel burn or other issues. Once I replaced mine, engines performed like new. Obviously you need to clean VST tank, filters and use good fuel. Taken care of, these engines are great and easy to work on.

 

[ocnslr]

We purchased our 270 Islander new in 2002 with a single 250HP OX66. With a normal to heavy fishing load, we would run at 4200RPM, getting about 22-23kts and burning 18-20GPH. So, about 1.2nm/gal. And that is with a well-maintained engine. WOT was 5450RPM, burning 28-29GPH and making 30.5kts.

With 465hrs on the single, we repowered in Oct 2005 to twin F150's. Cruise speed increased to 27-28kts at 16-17GPH, with WOT of 36.5kts at 28-30GPH.

All numbers above are in fair to moderate sea conditions. If is gets snotty and you have to trim the bow down to improve the ride, then the fuel consumption increases significantly.

We repowered to increase our fuel efficiency so we could fish offshore with the single 150gal tank on our Islander.

I would be very surprised to see you get 2.5MPG at 30MPH, but wish you the best.

Brian

 

[Tuna Man]

I also own a Taurus SHO with Eco-boost, I agree they do not sip fuel as advertised...

Back to the original question, I used to own a 92 Explorer with hardtop, dual tanks, etc. I repowered in late 1999 with a 2000 250 OX66 that was mounted on the factory bracket. I used to burn about 7gph at 7knots trolling offshore, burned about 3gph at 2knots trolling for striped bass, burned about 14gph cruising at 25knots, and burned about 27gph at wot (38knots). Best I ever saw cruising was lightly loaded (two people and only twenty gallons of fuel) was 2.5 statute mpg. We ran to the canyons here in NJ several times when the conditions allowed, we would burn between 130 and 155 gallons per trip. I used to bring extra fuel with us, yes it was dangerous, but I was a little younger. By the way the NJ canyons are about 90 statute miles from my inlet.

I now own a 20006 Marlin with twin F250 engines. Trolling for bass we burn between 2 and 3gph, trolling for tuna we burn betweeen 3 and 4gph depending on seas and speed, cruising and wot are significantly higher as we actually start to use all those ponies. Best we see at cruise is 1.5 statute mpg.

My point is that while the 250Ox66 is a reliable motor on most accounts, I would not call it thrifty by any means. I would suspect a new F250 or even F300 would cut the trolling fuel consumption in half (yes literally in half). I also suspect the cruise numbers would be better by about ten or twenty percent. The reason I keep mentioning trolling is because we do a lot of trolling. I have made trips with five guys on the 30 marlin that we actually burned less fuel than we would have with four guys on the 24 Explorer (these were not canyon runs). I have had several trips to the canyon that the outboard(s) did not stop running the entire trip, with the four strokes they sip fuel under light load.

 

[family affair]

Wow. I stand corrected! I didn't think we would have someone like Tuna Man with virtually the same rig to give feedback. I was giving my guesstimate based on my experience.
I have to say I'm surprised by the poor economy reported by Tuna Man. The 225 and and 250 ox66 share almost all of the same parts. Our fuel economy has been far better, but we have no bottom paint, hard top, and well 25hp, etc!
As for my claims, I'm basing this off our experience, GW test data for my exact set-up, and a Journey with a 250 4 - stroke tested by GW.

 

[The_Chain]

I also own a Taurus SHO with Eco-boost, I agree they do not sip fuel as advertised...

Back to the original question, I used to own a 92 Explorer with hardtop, dual tanks, etc. I repowered in late 1999 with a 2000 250 OX66 that was mounted on the factory bracket. I used to burn about 7gph at 7knots trolling offshore, burned about 3gph at 2knots trolling for striped bass, burned about 14gph cruising at 25knots, and burned about 27gph at wot (38knots). Best I ever saw cruising was lightly loaded (two people and only twenty gallons of fuel) was 2.5 statute mpg. We ran to the canyons here in NJ several times when the conditions allowed, we would burn between 130 and 155 gallons per trip. I used to bring extra fuel with us, yes it was dangerous, but I was a little younger. By the way the NJ canyons are about 90 statute miles from my inlet.

I now own a 20006 Marlin with twin F250 engines. Trolling for bass we burn between 2 and 3gph, trolling for tuna we burn betweeen 3 and 4gph depending on seas and speed, cruising and wot are significantly higher as we actually start to use all those ponies. Best we see at cruise is 1.5 statute mpg.

My point is that while the 250Ox66 is a reliable motor on most accounts, I would not call it thrifty by any means. I would suspect a new F250 or even F300 would cut the trolling fuel consumption in half (yes literally in half). I also suspect the cruise numbers would be better by about ten or twenty percent. The reason I keep mentioning trolling is because we do a lot of trolling. I have made trips with five guys on the 30 marlin that we actually burned less fuel than we would have with four guys on the 24 Explorer (these were not canyon runs). I have had several trips to the canyon that the outboard(s) did not stop running the entire trip, with the four strokes they sip fuel under light load.

thanks I figured by my calcs that I was getting 16 gph at 23 mph so were about on the mark...good to know, thanks for all the advice guys

 

[family affair]

Chain,
Food for thought...
I know my set-up isn't identical to what you guys are running, but I can't help but think something with your engine isn't 100% for you to be burning twice what Grady tested with the 225. With a badly carboned-up engine and fouled O2 sensor we were getting numbers similar to what you have now. We don't burn 16 gph unless running 40mph @ 5k rpm. WOT is only 22 gph.

If you find a fouled O2 I have a proven solution blessed by a Yamaha master tech for ~ $50. A pro decarb and new O2 might be a worthwhile investment.

 

[grady33]

When one of my engines was acting up, we tried and tested everything. Engine was shaking at lower speeds. Finally with several calls to Yam HQ, they suggested replacing the 02 sensor. Told me that after 12 years the sensor was past its due life. It tested fine but when we replaced it, the engine worked as good as new. As previous poster said, cheap investment and one I would due - especially if engines are old and sensors never replaced. Cleaning won't help at this point I'm guessing.

 

[Winged Pig]

Did that stop the shaking at low speed?