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Towing pontoon boat...TERRIBLE MILEAGE

Max Attitude

Max Attitude

Typical White Person
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My dad picked up an 06 LBZ. We drove down to Marco Island, FL this past Sat towing our 22 foot pontoon boat. Got 9-10 mpg. Do you know how much a programmer will help the mileage? Is that mileage normal for pulling a pontoon boat? I read about someone else complaining about mileage pulling a pontoon before ...I think on DP. Everyone there blamed it on the pontoon creating a lot of drag but it felt like it wasn't even behind us. I was expecting at least 12mpg. The truck also has a solid fold tonneau cover on it. We were basing mileage according to what the dic said but I also know it was very bad cause I have the same size tank and know what I average per tank.
 
I gotta admit, pontoons boats are bad for drag, but 9-10mpg, sound like you've got something else gong on. what style of trailer was it on? the one that fits between the pontoon or the kind the the pontoon sits in a cradle?
 
The kind where the pontoons themselves sit in cradles. It's a galvanized trailer, 2 axles. My guess is around 3-4 thousand pounds total.

Outside of towing the truck seems to do great on mileage.
 
the reason I asked is because of that style the boat sits up alot higher for more drag. did you happen the check the trailer brakes to make sure they weren't dragging? the whole low use deal. what do you normally get for mileage?
 
According to the dic he gets around 17.5 average....19-21 on the highway. Haven't hand calculated it much yet...he just got it a short time ago.

The speedo is off by about 2mph according to the gps.
 
I'd be double checking the trailer. the only other thing that comes to mind' is your running outside the powerband and that's killing the mileage.
 
What I've learned having owned 2 different generation DMax's, is that no matter the size, weight or shape of the trailer, anything hooked to the hitch gives terrible mileage.

My best was 14.8 out of my 07 pulling about 8000 lbs in an enclosed tandem axle, running at 70 mph.

9-10 is pretty horrible though. His air filter might be due for a change. They may look fine but those Donaldson's will clog up. Just ask RayMich.
 
Soooooooo, I went and looked at a skid loader. Unloaded I got 17.8 running 70mph. I bought it, hooked up my 25ft gooseneck and guess what? 10.6 on the way, 9.8 loaded on the way back. i don't care what anyone says, we have trucks. They aren't made to get good mileage. If you buy a truck for mileage get a 2wd Nissan or Yota. Otherwise, enjoy the power, cus it don't come free.
 
Well with these trucks you should be able to pull off better mileage than that. The fuel filter I changed right before we left. The air filter was good according to the indicator but I'll check that before we leave for home tomorrow. We drove anywhere between 70 and 78mph. When we drove 70 the dic said 9.8 mpg. 75 and higher was in the 8 mpg range.

He has Goodyear Wrangler Silent Armor 265's and the speedo is off by 2-3mph. Is it safe to say we're getting maybe 1mpg better than the dic thinks because the tires throw it off?

I know it's a truck but dropping 10mpg on the highway seems a little crazy just by pulling a 3-4k pound pontoon. It doesn't struggle whatsoever.

Another thing I noticed....if he hammers down on it unloaded it'll blow a little black stream of smoke....is this common for stock tuning? I know mine didn't do that but his has more power stock also.
 
Unit453 said:
What I've learned having owned 2 different generation DMax's, is that no matter the size, weight or shape of the trailer, anything hooked to the hitch gives terrible mileage.

My best was 14.8 out of my 07 pulling about 8000 lbs in an enclosed tandem axle, running at 70 mph.

9-10 is pretty horrible though. His air filter might be due for a change. They may look fine but those Donaldson's will clog up. Just ask RayMich.
Click to expand...

Yours was double the weight...yet you managed to get about 4-5 mpg more. Something isn't right here. The trailer you pulled may have been more aerodynamic but jeez.
 
I would not say it's terrible. Pontoon boats are not the most aerodynamic things to trailer. Look underneath the thing. All those pockets under there equate to wind drag.

I have a 10K camper and I average 10-12 mpg on the highway. I also have a small 12' trailer I use for my 2 4-wheelers. When towing the bikes I avg 13-15 mpg. The difference between these in weight is astounding but all the wind drag on the small trailer with the bikes just sitting there is probably about the same. Maybe more.

The camper is completly closed except the axels. The only wind drag comes from the front of the camper. It' like holding a 4x8 sheet of plywood above the cab.
 
Max Attitude said:
Well with these trucks you should be able to pull off better mileage than that. The fuel filter I changed right before we left. The air filter was good according to the indicator but I'll check that before we leave for home tomorrow. We drove anywhere between 70 and 78mph. When we drove 70 the dic said 9.8 mpg. 75 and higher was in the 8 mpg range.

He has Goodyear Wrangler Silent Armor 265's and the speedo is off by 2-3mph. Is it safe to say we're getting maybe 1mpg better than the dic thinks because the tires throw it off?

I know it's a truck but dropping 10mpg on the highway seems a little crazy just by pulling a 3-4k pound pontoon. It doesn't struggle whatsoever.

Another thing I noticed....if he hammers down on it unloaded it'll blow a little black stream of smoke....is this common for stock tuning? I know mine didn't do that but his has more power stock also.
Click to expand...


First of all, you might as well throw away that little filter minder thing. Those are completely worthless and should not be used to judge how well its flowing. Its its blowing black smoke, that means its overfueling and not getting enough air. Basically, on a stock truck, I'd bet his filter is shot and isnt allowing enough air to get in so its dumping fuel. Its the only thing that makes sense.

He has Goodyear Wrangler Silent Armor 265's and the speedo is off by 2-3mph. Is it safe to say we're getting maybe 1mpg better than the dic thinks because the tires throw it off?
Click to expand...

Yep. If the speedo is off, so is your mileage. Its not accurate anymore so its impossible to tell how many miles you've actually gone with gallons burned. You're short changing yourself.

If its off by 3, then with the speedo readin 60, you're actually doing 63. So in 120 miles on the odometer, you actually traveled 126 miles. In 1200 miles, you actually traveled 1260. Unless my math is off, which it probably is, there's no way to accurately calculate your mileage.

I have to do this on my car since I'm running 18" wheels instead of the stock 16's. My speedo is off by 4 mph at 60. So in every 300 miles driven per tank, I have to add 30 miles to it to get an accurate number. And last tank of fuel it was the difference between 17.5 mpg or 20.5 mpg actual mileage, using the difference in the speedo.

3 mph may not look like much but over the course of an entire tank of fuel, you're losing 20-40 miles that should go to your benefit.
 
Ok, checked the filter....looks fine but man that's a weird filter. I don't know if you could ever really tell it's dirty. I don't usually go by that filter gauge but mine on my truck doesn't seem to be off by too far....I always check it every oil change.

The oil on his truck was supposedly just changed when he bought it. Also, they had to replace the oil pan gasket before the purchase...so i would hope they had put brand new in. I just checked it and it's pitch black! So we're getting the oil changed today and a new air filter. Hopefully with a combination of these things we'll yield some better mileage.

Thanks for all the replies fellas.
 
I'd be curious to know if this did anything.

When you take out those Donaldsons, blow through one end and put your hand at the other. You'll see just how well they do flow. If sand and shit comes out the other side, you'll know it was getting bad.
 
I kinda hit the filter on the ground and sand came out...bad filter?

We're trying to find a shop in florida near us that does oil changes for a reasonable price. A couple shops said $100 (yikes) and a couple didn't know what a Duramax was. We don't really have the stuff to do it ourselves..we may end up buying an oil catch pan and crawling under it with a channel lock in the condo parking lot.
 
Drain plug takes a 16MM wrench IIRC, you should consider replacing it with a fumoto oil drain valve, I think I'm gonna get one after my last fiasco. It is so easy to give these things an oil change, but then I've done it on all my vehicles. Parking lot would be ok, try and find a big piece of cardboard to lay on and make sure your catch pan holds 12 quarts.
 
I've been saying I'm getting a fumoto oil drain valve since 2004 when I bought my LLY. Just havent gotten around to it yet. Mainly, because I'm retarded and evidently enjoy oil everywhere, especially running down my arm and pooling into my skid plates.
 
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