I just lost 8 MPG!!

[DieselCamper01]

Pulling my 30 ft TT I get about 10-10.5 staying under 70 mph. Empty, which is not often I get maybe 15.5 at best. This is with a 4wd not 2wd. That will make a big difference.

[jinxie]

Thanks for all the replies.
It must be something obvious, but I cant seemto track it down.
The 5th wheel is just standard height. It is 6' in the upstairs master bedroom, so really only about 4' sticking up above the truck.
I thought about bearings, but if I had that much of resistance to roll Im sure the bearing would blow! Also, the truck/trailer start to roll immediately when I take my fot off the brake, so I figure I could eliminate dragging brakes and bearings.
When I fill I just fill it until the hose clicks off, then go up to the next dollar amount. I may be out a little there, but not enough to make a huge difference. I still burned $45 of fuel in 77 miles!
I have 285/75/16 tires. The cruise was set in between 60mph and 70 mph. At 75mph speedlimits, I was getting passed regularily, so the speedo must be close.
Also, what rpm should I be pulling in? I can run it in OD at 1800-2000 rpm, or in direct at 2500-2600 rpm. Is lugging it down better at lower rpm, or does that put too much strain on everything?
Thanks for the help. What can I try because we are going out this weekend again....I would like to see if I can improve the mileage on this trip!

[danskool]

Originally Posted by Kwikkordead

Also, I would want them to be easily removed once arrived at the destination.
I think they make an empty truck look like a tricerotops.

Those wings for the top. I read an article that they didn't help mileage but helped with bugs on the front of the nose.. Most claimed 0 mile improvement. Some claimed 1 to 2 mile increase. I figured if it kept bugs off it must be creating some sort of lift in the wind to get the bugs up and over. As soon as i get caught up. I want to make one or shop around. If it helps with bugs and i get 1 mile per gallon increase. It will pay for itself. I will have to search around and look for that article. It had wind testing and the hole 9 yards.

One on ebay. Looks like one could make one.
http://cgi.ebay.com/ebaymotors/Air-W...spagenameZWD1V

[twags6]

Stock tires are 265/75/16's so the 285's might throw the speedo and mileage off a little. Trucks with a 3.73 rear run just a hair under 70 at 2000 rpm's.

[gunfrk]

A few things that kill mileage are

1. old oil ( change it)
2. old fuel filter ( ditto)
3. Leaking up pipes or doughnut gaskets, at 133k it is indeed possible. This happened to be my major problem.

[jinxie]

I just had the oil changed, but not the fuel filter. I will change that. Is there just the 1? Is it an inline or spin on? Location?
Also, what are the up pipes? I dont have a boost gauge, but I wonder if i should pull a pipe, weld in a fitting and run a gauge and go for a test run.
What should boost be on a stock truck?

Thanks

[danskool]

Welcome to guzzle's PSD Fuel Filter Change Web Page Fuel Filter
3-Gauge Install Pictures Hook boost gauge here

Up exhaust pipes run between motor and firewall. head up from manifolds .

[danskool]

Forgot the boost.

I am all stock. I get a whimpy 15-16 psi boost pressure wot .. 17-18 waist gate unplugged and capped which i don't run normally like this. I even checked for leaks. Spent many hours trying to get more. But it seems i will need more mods and money to get more.

[twags6]

Originally Posted by danskool

Forgot the boost.

I am all stock. I get a whimpy 15-16 psi boost pressure wot .. 17-18 waist gate unplugged and capped which i don't run normally like this. I even checked for leaks. Spent many hours trying to get more. But it seems i will need more mods and money to get more.

You probably already know this, but a cheap way to get more boost is the 6637 air filter and ditch the muffler (and cat if you have it). I pulled the whole section of exhaust from the clamp on the front of the muffler to the tip off. Between those two mods and the waste gate line unplugged, I can trip the SES light and hit about 25-26psi.

[parkland]

Originally Posted by jinxie

Thanks for all the replies.
It must be something obvious, but I cant seemto track it down.
The 5th wheel is just standard height. It is 6' in the upstairs master bedroom, so really only about 4' sticking up above the truck.
I thought about bearings, but if I had that much of resistance to roll Im sure the bearing would blow! Also, the truck/trailer start to roll immediately when I take my fot off the brake, so I figure I could eliminate dragging brakes and bearings.
When I fill I just fill it until the hose clicks off, then go up to the next dollar amount. I may be out a little there, but not enough to make a huge difference. I still burned $45 of fuel in 77 miles!
I have 285/75/16 tires. The cruise was set in between 60mph and 70 mph. At 75mph speedlimits, I was getting passed regularily, so the speedo must be close.
Also, what rpm should I be pulling in? I can run it in OD at 1800-2000 rpm, or in direct at 2500-2600 rpm. Is lugging it down better at lower rpm, or does that put too much strain on everything?
Thanks for the help. What can I try because we are going out this weekend again....I would like to see if I can improve the mileage on this trip!

Sorry bud, but when kwik said something about campers with big fronts stickiong up, this would apply to you.

My camper is 30 ft, and it is all one level, barely above roof of truc, and the only way i can tell its back there is if I pass a car over 140 it gets the speed wobbles.

I normally burn about 10 liters an hour at 100 km/h.

With camper about 12.

Even with strong headwind mileage wont go much lower. I'd say both numbers there will never deviate more than 2 either way.

[Kwikkordead]

Originally Posted by danskool

Forgot the boost.

I am all stock. I get a whimpy 15-16 psi boost pressure wot .. 17-18 waist gate unplugged and capped which i don't run normally like this. I even checked for leaks. Spent many hours trying to get more. But it seems i will need more mods and money to get more.

This is a picture of leaky up-pipes on an E-450 Powerstroke.
See all the black streaks on the pipes. That is exhaust drive pressure leaking out before it gets to the turbo, which will cost you boost effeciency.
When I fixed mine, I gained a couple MPG's. Get the bellowed up-pipe kits vs the donut style. They cost three times as much, but it is a permanant fix.

Originally Posted by twags6

You probably already know this, but a cheap way to get more boost is the 6637 air filter and ditch the muffler (and cat if you have it). I pulled the whole section of exhaust from the clamp on the front of the muffler to the tip off. Between those two mods and the waste gate line unplugged, I can trip the SES light and hit about 25-26psi.

You'll get better performance if you plug the WG back in. Too much exhaust back pressure will kill top end power. Personal experience. I get more power if I run with the WG connected than not.

Originally Posted by parkland

Sorry bud, but when kwik said something about campers with big fronts stickiong up, this would apply to you.

My camper is 30 ft, and it is all one level, barely above roof of truc, and the only way i can tell its back there is if I pass a car over 140 it gets the speed wobbles.

I normally burn about 10 liters an hour at 100 km/h.

With camper about 12.

Even with strong headwind mileage wont go much lower. I'd say both numbers there will never deviate more than 2 either way.

You must have a bumper pull.

[cangim]

I would agree that if you have a 6ft ceiling up top than you have a tall trailer. However, that been said, I usually get about 10mpg towing on average and that is with terrain and such. If there is much of a head wind it drops to around 8mpg. This is with a trailer that is closer to 34' and loaded up probably puts me over 20K truck and trailer combined. Sad part is, unloaded I still get around 14-15mpg, but this is going 80mpg on interstate vs. 65mpg towing. If I didn't feel like I would be run over, I would tow at 55mph which puts me right at 2000rpm in 3rd.

[GEugeneS]

I get 10-12 mpg pulling a 15K trailer, usually closer to 10. I run a dually with 4:10 rear end too. But i rarely exceed 60 mph here in Cali. 8 mpg seems low to me for a small trailer and stock.

[parkland]

Originally Posted by Kwikkordead

This is a picture of leaky up-pipes on an E-450 Powerstroke.
See all the black streaks on the pipes. That is exhaust drive pressure leaking out before it gets to the turbo, which will cost you boost effeciency.
When I fixed mine, I gained a couple MPG's. Get the bellowed up-pipe kits vs the donut style. They cost three times as much, but it is a permanant fix.



You'll get better performance if you plug the WG back in. Too much exhaust back pressure will kill top end power. Personal experience. I get more power if I run with the WG connected than not.

You must have a bumper pull.

It is a bumper pull, and heavy as heck.

She's older, but with solar panels on the roof, 12v battery bank, 120v inverter, sat TV, custom sound system installed (12v system), and the air conditioner installed too, we enjoy it.

I tried pulling it with my 1/2 5.7 chev.... yeah right. On the f250 7.3 she barely levels, and I can pull in overdrive no problem at all.

[mndiesel]

I just got back from a trip to my family reunion in New England and I averaged 10-10.5 mpg with my 12k lb 5th wheel. I had the cruise set at 67-70 and the tailgate off. I get about 17mpg mt at the same speeds. All hand caculated