8-9 MPG while towing - expected better

[woolznaz]

I have a 2006 F250 4x4 Diesel crew cab. Max tow capacity is about 12,500 pounds.

I'm towing a 25' South Bay tri-toon with a Volvo 5.7 inboard/outboard on what is supposed to be a very nice trailer made by Extreme Custom Trailers. It's a dual axle with 4-wheel disc brakes...blah, blah, blah. Boat + engine + motor + fuel + gear + trailer = about 6,200 lbs.

The truck gets around 15 MPG when not towing. Since it's a diesel and is engineered to tow so much, I actually expected to get 11 or 12 MPG when towing my toon. Yes, it's a heavy pontoon, and I know pontoons are big square rigs, but it's just a pontoon, not a 30+ foot fiberglass boat. I actually thought it would tow the boat and hardly notice it was back there. That's not the case.

Does this sound normal? Should my mileage drop off this much on a diesel pulling a toon? Do you think I might have a brake sticking off and on or something? I just expected better MPG than this and thought the truck would handle it well.

Please, please, please..... let's not start the Ford vs Chevy vs Dodge argument here. Just trying to find out if this sounds about right.

Thanks for any thoughts.

 

[Doug N.]

Re: 8-9 MPG while towing - expected better

That sounds a little bit low. The mileage I get towing a 40' fifth wheel with the 7.3 l powerstroke would bring tears to your eyes, though. How fast are you going? It helped me a bunch to take my foot out of the engine compartment. The wind makes a big difference too. I try not to have to accelerate too fast either. I noticed a big difference when I checked my tires and got the inflation right. I can tell a big difference depending on the fuel; bad fuel dropped my mileage by 4 mpg. Try getting the higher grade diesel fuel.

Sometimes I get real picky about mileage; other times I figure I'm helping the environment by recycling...dinosaurs.

 

[BigB9000]

Re: 8-9 MPG while towing - expected better

my caprice gets about 27 highway
about 8 towing a jetski.

Turned out to be a collection of bad sensors (couldn't handle the weight I guess)

 

[Lrider]

Re: 8-9 MPG while towing - expected better

Welcome to owning a boat, I get about 6 mpg towing my 8,000 pound boat with my 2,000 pound Jeep Wrangle

Then again I only get about 12 towing nothing

 

[JRJ]

Re: 8-9 MPG while towing - expected better

8 to 9 is ridiculous, but some diesel trucks and motor homes only get 5-6. There are so many variables. Weight is just one. Speed, mods for horse-power gain, tires, gear ratio, road and weather conditions, not to mention the engine displacement all play a part. Good luck.

 

[KermieB]

Re: 8-9 MPG while towing - expected better

I have a V6 '08 Ford Escape that's rated to tow 3500 lbs and I have 2500 lbs of boat and trailer. At 70 MPH on interstate, the car gets about 28 MPG. Towing the boat on the intestate (I slow down to 60) I get about 18 MPG.

I'm good with it....

 

[Silvertip]

Re: 8-9 MPG while towing - expected better

You are towing one of the least aerodynamic rigs on the highway and wind resistance is your enemy. Towing a pontoon is like towing a barn door and the faster you go the worse it gets (and it gets worse quickly when you get over 50 MPH). It doesn't matter whether you have a diesel or gas powered tow vehicle. They both suffer. Slowing up even 5 MPH can help. As an example, both my fishing boat and pontoon when loaded for a trip weight within 500 pounds of each other with the pontoon being heavier. Fuel economy drops dramatically with the pontoon in tow and towing in OD is out of the question except on flat roads with no headwind whereas the boat is simply not an issue either way. It is not the weight difference but rather the shape of the boat that causes the drag.

 

[buzzhd]

Re: 8-9 MPG while towing - expected better

heck i get 10 mpg with my Dodge 3500 w/5.9L pulling my 30ft toy hauler. its like pulling a barn. when pulling my 20ft Sea Ray I get 16mpg and empty around 18mpg.

 

[Charlie in TX]

Re: 8-9 MPG while towing - expected better

Not a Ford vs comment but a Ford 6.ut0 PSD. It was a mistake. They never should have put that motor in. I had a 'o4 6.0 PSD. Loved the truck, hated the motor.

Having said that, your mileage sounds on the low side. At least if you are getting 15 hwy unloaded. You can get that with any of the big 3s gas motor. I don't know this for a fact, just 5 or 6 6.0l PSD owners talking over a few beers. These motors run pretty well when everything is set just right. Over time they fall out of peak adjustment. Get it to a good mechanic and see if they can get it back to where it needs to be.

 

[woolznaz]

Re: 8-9 MPG while towing - expected better

That sounds a little bit low. The mileage I get towing a 40' fifth wheel with the 7.3 l powerstroke would bring tears to your eyes, though. How fast are you going? It helped me a bunch to take my foot out of the engine compartment. The wind makes a big difference too. I try not to have to accelerate too fast either. I noticed a big difference when I checked my tires and got the inflation right. I can tell a big difference depending on the fuel; bad fuel dropped my mileage by 4 mpg. Try getting the higher grade diesel fuel.

Sometimes I get real picky about mileage; other times I figure I'm helping the environment by recycling...dinosaurs.

Yeah, those 7.3's did really well. I think the 6.0's get better than the 6.4's. It seems like the more they make diesels "better and better", the fuel economy gets worse and worse.

As for speed, I don't really have a very heavy foot. I take off pretty gradually and basically baby it, especially when towing. I have not used any fuel additives and I just buy the basic diesel fuel. I'm not even sure where to get higher grade diesel.

By the way, I know a lot of tree huggers would faint, but I think you are exactly right with your recycling dinosaurs quote. You cannot get more environmentally friendly than to run the wheels off your old 7.3. My neighbor has gone through 3 Priuses with his nose in the air like he cares more than others while I keep driving the same old cars. Who's more green?

Anyway, thanks for the replies so far. I was just surprised how much the mileage dropped off with a 6,000 lb box behind it. I still expected 11 or 12 MPG.

 

[cobra99]

Re: 8-9 MPG while towing - expected better

I would consider towing your boat with the cover on if you have a towable cover. I have a friend who has the same problem towing a 25' pontoon with an 03 powerstroke f350. I think that wind is your biggest enemy when towing. The pontoon boats sit higher on the trailer and there is nothing to block the wind off the cab of the truck. Keep trying different scenarios and good luck

 

[Doug N.]

Re: 8-9 MPG while towing - expected better

Go to the semi island and get #1 diesel. Usually #2 is OK; #1 costs more but it is like buying premium gasoline. I filled up once in texas and got a bad batch of #2 and I could tell immediately that it was awful fuel.

I'd say that if you get your boat on the water, it's worth the fuel to get it there.

Best of luck.

D

 

[Fisherball]

Re: 8-9 MPG while towing - expected better

A good friend spent 20 years owning a small towing business. It always uses at least the same amount of gas to move 2 vehicles. His truck would use as much gas to tow the car as it would take to drive them both the same distance, usually more. When I bought my current boat 120 miles away my Blazer got over 23 MPG empty going 60 mph. Coming back with the boat it got 8 mpg.

 

[freeisforme]

Re: 8-9 MPG while towing - expected better

I had a 1997 Ford 7.3 Power stroke dually, 4x2, it got 18 mpg on avg. but only 11 over the road pulling a 4 horse stock trailer through the mountains. Several complaints to the dealer and Ford, got me a new trans and an ECU reprogram, after that it got 15-17 towing, and 19 empty. It did so for 120K till I sold it.
The trailer it pulled was heavy, had tandem axles and hauled four horses and tack. The next truck as a 6.0 Power Stroke, I dumped that after only 4 months. It did fine for mileage, got 18 loaded or not, but couldn't stay out of the shop. The last two trucks were just as bad. I wish I kept my 7.3L 1997.

I've got a Dodge now, not great on fuel but consistent and so far reliable. I get 16-17 all around, maybe a little better over long trips. As with the Fords, it rarely leaves the yard without a trailer.

If you getting less than say 11 towing such a light load, I'd see what the dealer can do to remedy that. My 1986 GMC with a 454 dually did at least that when towing.

Just for comparison, I just drove a 28' box truck from NY to FL, with the air blasting and loaded to the limit, it got 9 per gallon and that was with a DT466 in a Penske rental truck and driving with no concern for mileage.

 

[dave11]

Re: 8-9 MPG while towing - expected better

For comparison I have an F250 Super Duty with the V10 engine. Pulling a 2500# boat on the highway I get just under 12MPG, and just over 15 MPG without the boat.

 

[sprintst]

Re: 8-9 MPG while towing - expected better

+1 on the wind resistance. You're pushing a lot of air. My neighbour was talking about towing his loaded trailer with Bobcat, etc and getting great mileage but when he tows his travel trailer which is lighter his mileage drops dramatically.

It's like carrying drywall sheets off the truck into the house in the wind. Tried to get them in the house before a storm kicked up provided a great example for me.

I'd still keep an eye out for people with same truck/engine combo to see what they get for base mileage as there may be tweak via ecu upgrade or chip install.

You are towing one of the least aerodynamic rigs on the highway and wind resistance is your enemy. Towing a pontoon is like towing a barn door and the faster you go the worse it gets (and it gets worse quickly when you get over 50 MPH). It doesn't matter whether you have a diesel or gas powered tow vehicle. They both suffer. Slowing up even 5 MPH can help. As an example, both my fishing boat and pontoon when loaded for a trip weight within 500 pounds of each other with the pontoon being heavier. Fuel economy drops dramatically with the pontoon in tow and towing in OD is out of the question except on flat roads with no headwind whereas the boat is simply not an issue either way. It is not the weight difference but rather the shape of the boat that causes the drag.

 

[AlmostFamous]

Re: 8-9 MPG while towing - expected better

+ another 1 on wind resistance. At work we run Ford PSDs, they range from 2004-2010s. I can pull our test rig which weighs about 8,500 lbs and get 10-12 mpg. But the rig is very low, 25' long and only about 5 feet tall, maybe less than that.

Now, if I pull our 28' enclosed trailer EMPTY, I'm lucky to get 7-9 mpg, and god help me if there is a headwind then its 5-7 mpg. It's got a raised roof and there is just a TON of wind resistance. Which is what you have with your big tri-toon. A good cover would help streamline it and maybe grab a few extra mpgs.

Now, we have found that there is a break over point on speed. On our trucks it seems that any thing from 30-60 MPH, MPG stays fairly steady. Now we start pushing 65-70+ MPH, the MPGs really start to fall off.

In short, I think you are getting about the right MPGs for what you are pulling.

 

[25thmustang]

Re: 8-9 MPG while towing - expected better

For comparison I have an F250 Super Duty with the V10 engine. Pulling a 2500# boat on the highway I get just under 12MPG, and just over 15 MPG without the boat.

I have the exact same truck, F250 V10. I get in the 11-12 mpg range unloaded. Towing a 25' boat (maybe 6500 lbs or so) I got 9-10. Towing my car on the trailer (4500-5000 lbs) I get right around 10.

 

[smokeonthewater]

Re: 8-9 MPG while towing - expected better

perfectly normal towing that parachute.... I get 6 towing my 10,000 lb fifth wheel and 4,000 lb jeep I get 9 towing my 9,000 lb boat and I get 12 empty. I have a 7.3 with 305,000 miles on it. The 6.0's get better milage empty but they drop more with a heavy (or high drag) load than the 7.3's
You might actually get better milage pulling a 30' glass boat.....

Drop your speed to 5 mph under the limit and you will likely notice a profound improvement..... Also stop using the brakes any more than you have too..... you have been to the ramp before.... you know the turn is 1/4 mile ahead, take your foot off of it and coast...... You are losing speed on a hill but you have another to go down..... do you mash the accellerator and then ride the brakes down.. nooooo let your speed fall and come back up on the downhill..... If you have to stop or pull over to let traffic by, try to do so at the top of a hill


EDIT: btw my figures are HAULING BUTT empty or loaded , Also my truck has 4.56 gears and weighs about 10,000 lbs empty and holds 140 gals of fuel.... I am not a patient person and I generally pass everything on the road.....pedal flat on the floor on the uphills while watching the egt's climb. 26,000 lbs cruise set on 80 mph..... 1000 miles one way. .... not bragging but rather just adding context for figures

 

[g4olfer]

Re: 8-9 MPG while towing - expected better

I am pulling a 26 ft Bennington Tri tune with a 5.O mpi so weight of the boat should be pretty close, my duramax is getting 12-13 pulling at 65 MPH. A friend has same year ford as you and he had to chip it and then mileage came up dramatically. I haven't chipped my 09 GMC yet, but did it on my 06 and mileage picked up approx 2-3 while pulling and 4-5 when not pulling.