Engine/Transmission (1994 - 1998) poor fuel mileage towing

[PetesonM]

I took my truck for the maden towing voyage with about a 8000 lb in tow and got dissapointing results with the fuel mileage. This is on the '95 and towing relatively flat (wisconsin) I got a little above 10mpg. Everything on the truck worked flawlessley other then the fuel level sender which seams to be less than accurate. But after it showed I was empty after just 200 miles I filled up and put in around 20 gallons. I have a #10 forward, star wheel forward, afc with the light spring, pretty much everything I can do to get fuel in there so I understand a small problem but this is a little rediculous.



Where is the first place I should start looking at adjusting things. It wasn't smokey if I didn't want it to be and pulled better than I expected. I love this truck but would like to get into the upper teens like others commonly do.

 

[GAmes]

Weight isn't nearly as much an issue as speed and the aerodynamics of the trailer. What were you pulling and how fast?

 

[PetesonM]

I have a fairly low to the ground 18 foot dual axle car hauler with a not humungus but rather built Jeep Cherokee on it. We were driving between 65 and 68mph. It was rather windy but most of it was a cross wind.

 

[GAmes]

I have a fairly low to the ground 18 foot dual axle car hauler with a not humungus but rather built Jeep Cherokee on it. We were driving between 65 and 68mph. It was rather windy but most of it was a cross wind.

Crosswinds are nearly as bad as headwinds. I didn't see where you advanced you timing. 15. 5 to 16 btdc will improve you mileage, as will dropping your speed a little. Just stay over 1800 rpm. Stop and go (traffic lts, etc) also play hell with your mileage if you like to accelerate quick and wait till the last minute to slow down and stop.

 

[PetesonM]

Timing is right in the 15. 5 to 16* mark and this was almost all highway driving. Very few stops or slowdowns.

 

[NHays]

Whats your gearing and tires?

 

[PetesonM]

4. 10's and 285's that measure around a true 32" or so.

 

[Driftwood Ram]

What kind of mileage did you expect?? I get between 10 and 11 with 3:54's towing the Alfa. Oo.

 

[HLEschenko]

10. 6 - 11. 7 with a 5000# 24 foot travel trailer here.

 

[Champane Flight]

12

I have gotten a high of 18, and a low of twelve. It will not drop under twelve, headwind, fifthwheel, and boat. 3:54s... five speed... two wheel drive. .

 

[CorneliusJ]

97 4x4, 3. 54, auto, #10 plate, 3k gsk, 245. 75. 16 80psi, 17,000 combined weight. 13. 5 on flat, 10-11 in mountains, 60-65 mph. 22-23 mpg on flat, not towing, 60-65 mph.



Jim

 

[NHays]

With my truck from above. I get 17-19mpg on highway empty at around 70-75mph. 12-14 mpg pulling 30ft Goose with 14000lbs(GCW 26,950lbs) of tractor without a cad, on slightly hilly terrain moving 60-65 mph, on flat i get 15mpg. I get 16mpg pulling an empty 14ft stock trailer in the wind. I am easy on the starts and stops when I have a trailer. Before I switched to a SuperB turbo I was getting 10-12 mpg loaded and 20-21 mpg empty. I noticed the HX35 is a good cruising turbo that ran best when empty and not so well loaded. the SuperB is nicer when loaded but not as nice when empty. I also run Toyo M55 285/75R16 triers. I try to stay in fourth gear when pulling and let rpms do the work, If I lug when I pull my fuel milage suffers. When I am empty or pulling an empty trailer I lug the engine, and it does fine. I notice that if the GCW is under 12,000 lbs i can run in fifth and get good milage, much over that and I have to slow down and keep it in fourth. not a power issue, just a lugging issue. I wish I had 4:10s sometimes, but 3:54s are nice when unloaded. My truck has two sweet spots. ~2000rpm unloaded in fifth, ~2500rpm loaded in fourth.

 

[dpuckett]

Is your trailer a lighter duty (maybe 7-9K GVWR- 5-6 lug 15" wheels) or heavier duty (12-14K GVWR- 8 lug 16" wheels) version? Reason I ask is a friend of mine has a 16+2 trailer with 15" bias tires that I swear pulls as hard as a 40' 24K GVWR gooseneck flatbed (based on pyro and boost readings at cruise), and that is empty. I hauled a dually on it from Houston to Cape Girardeau, and added a 7K truck (Ok, so it was a little overloaded); on the return trip lost 1mpg going the same speed on the same roads. Point it, is could be your trailer, combined with bad aerodynamics on the part of the load.



Daniel

 

[RDelissen]

4. 10's and 285's that measure around a true 32" or so.

that's your culprit right there ... even though I've got slightly smaller tires (265s) on a bad day towing my Jeep around it'll also drop to just above 10 mpg :-laf



But it averages around 13 towing though and that's at an elevation and with plenty of mountains around



Just take measurements over a lot more towing mileage than just 200 miles and then report back (the wind will make a huge difference like mentioned already) and I'm glad mine will pull long and steep hills in the southwest at 65 mph towing junk around and not having to worry about it. I'll gladly pay a few extra bucks on diesel a year to have that 'luxury', since that's what I bought the CTD for

 

[rsaderlund]

Don't forget to take in to account the odometer difference with the tall tires, unless you had it corrected. With my 305's I get 14 towing a 8000 lb 5ver.

 

[Vaughn MacKenzie]

I have two 12v trucks (see sig for truck info) and neither one gets as good of mileage towing as the two 24-valve trucks I had in the past did. I am almost convinced 24 valves do better under load.





Pulling a light 17' single axle camper my '96 gets 13. 5 - 14 on average at 62-65 MPH all highway. When I pulled the same camper with my '03 once it got over 18 at the same speed (that truck was HO shortbox 4x2). The last time I towed the camper was with my '98 and it got 12. 3, but it's a stock auto, stock timing and I was rolling along faster (almost 70). Still it should be in the same ballpark as the '03, not way worse.



I've towed my dad's old boat (17' boat) a considerable distance with my '01 HO 4x2 as well as with the '96. The '01 got 18, the '96 did 15. 5.