terrible gas mileage

Maximous · Post by **Maximous** » Fri Dec 01, 2006 7:33 pm

i just towed a trailer from my brothers house to my moms, about 115 miles, from a full tank, i am now down all the way to 1/4, 3/4s of a tank for 115mls???? also, the truck squatted pretty quickly while loading, which made me pretty mad, it has helper springs on it plus the RS9000X shocks on the highest setting, i have 30in tires, 3.73 gears and i was running 75-80 the whole time, the truck has like 33 thou milage, and has been getting worse and worse on mileage, last time it was at the dealer they mentioned some feul system clean thingy that was a standard thing at a certain mileage, i chalked it up to "Lets see what else we can get this dummy to pay for" they wanted like 150 bucks to do "stuff" to the fuel system, could not doing this have something to do with the terrible mileage, or has anyone else dealt with this and have an answer???? i really appreciate any help as i cant keep putting 35 bucks in gas in a truck that only gets 240s to the tank

04crewvt · Post by **04crewvt** » Sat Dec 02, 2006 3:20 am

A rough estimate of your MPG from what you stated would be around 9.5-10 MPG. You don't say the size of the trailer or the loaded weight but if the rear is sagging it's a good bet you were over the 500lb tongue weight on the trailer so my guess is your load was near max? Also you were running at high speed for towing most trailers are not rated to be towed at that speed and the truck would be working awfully hard under those conditions. I would say if these assumptions are right you got just about what I would expect form our trucks.
As for the fuel system have you changed the fuel filter yet? at 33k it should be due for it's second change from the factory original.

F9K9 · Post by **F9K9** » Sat Dec 02, 2006 4:17 am

You didn't mention if, you filled it up and actually checked the mileage. I have filled up at ¼ tank before and it only took 5 gallons. Just trying to give you a glimmer of hope there, Bro

Maximous · Post by **Maximous** » Sat Dec 02, 2006 6:05 am

the trailer was loaded with washer/dryer, sofa/recliner and a half empty keg haha, i have never changed a fuel filter (unless the dealer did it, it goes there for every oil change) and i filled it up from just under half a tank, but that doesnt matter because i reset the trip, so this sounds about right to yall????? i remember once before i changed my tires that i got a 300+ mile tank, now i am good to break like 260, is that actually just distance lost due to the different size tires, in other words i am still running about the same?? i know for a fact that their is a difference between actual speed and speedo reading

F9K9 · Post by **F9K9** » Sat Dec 02, 2006 6:34 am

You're going to read less miles traveled per tank with the larger tires. I don't think you're averaging any less than the rest of us. A true test would be an interstate trip using the cruise and staying at 65 mph.

Maximous · Post by **Maximous** » Sat Dec 02, 2006 10:34 am

65, are you kidding, "i cant drive, 65!!" haha, that was another question i was going to ask, what is a good cruising speed,

PS i filled up today, 149.5mls on the trip, my fuel quage was on and had been for probablly 10-15mls

F9K9 · Post by **F9K9** » Sat Dec 02, 2006 10:53 am

Maximous wrote:.................... "i cant drive, 65!!" haha, that was another question i was going to ask, what is a good cruising speed,

Then you're going to pay the dues for anything above 2,000 rpm. At 65 mph and my 33s (tire size calibrated) I'm running about 1700-1800 rpm and 2000 rpm at 75 mph.

04crewvt · Post by **04crewvt** » Sat Dec 02, 2006 12:58 pm

So you got 149.5 miles on approximately 13-14 gallons of gas at 75-80 MPH with a 1500lb load +/- including trailer and stuff. I assume you were in 3rd gear not overdrive which is not recommended for towing in our trucks for a guestimate of 10.7 to 11.5 MPG. I think you are doing about all you can expect without slowing down and keeping the RPM's below 2000 like Reed suggests.
Anything over 60 towing a trailer with our trucks is going to be awfully hard on gas no matter what you try.

kermit · Post by **kermit** » Sat Dec 02, 2006 3:09 pm

speed kills... gas mileage, that is.
Anytime I tow, even if its just my 14' jon boat, I ride the throttle and let the truck pick up speed down hill and slow it down up hill -- which is just keeping the rpms below 2000 like previously stateed.

LonestarZ · Post by **LonestarZ** » Sat Dec 02, 2006 8:45 pm

When was the last time you changed your fuel filter?

If your still on your factory fuel filter at 33K miles trust me that needs to be changed. Might even see a couple MPG's improvement. I know I did when I changed mine at 30K.

Maximous · Post by **Maximous** » Sun Dec 03, 2006 6:48 am

yeah i guess i should get around to changing that, just maybe!!!!

F9K9 · Post by **F9K9** » Sun Dec 03, 2006 8:33 am

LonestarZ wrote:When was the last time you changed your fuel filter?

If your still on your factory fuel filter at 33K miles trust me that needs to be changed. Might even see a couple MPG's improvement. I know I did when I changed mine at 30K.

Welcome aboard, Dave

LonestarZ · Post by **LonestarZ** » Sun Dec 03, 2006 2:11 pm

Thanks man.. now if I could just get someone with a Chevy ZR5 to sell their rims.

F9K9 · Post by **F9K9** » Sun Dec 03, 2006 4:26 pm

LonestarZ wrote:Thanks man.. now if I could just get someone with a Chevy ZR5 to sell their rims.

Sorry, I already sold mine and have been trying my best to spend the thousands ever since

cdnuser · Post by **cdnuser** » Mon Dec 11, 2006 6:04 pm

Just a thought...what gear where you towing in?

I use 3 for towing.

I also find my truck wants to sit at 3 grand. But then again I drive on the fastest highway in Canada. AVG speed on the 401 is 125-135 KMs about 80-85 m/hr

I need to do a full tune-up very soon

Maximous · Post by **Maximous** » Mon Dec 11, 2006 7:46 pm

i was in OD, i was sitting at like 2500, i think, but i was noticing today that i cruise around 2000 so not much difference

2kwik4u · Post by **2kwik4u** » Tue Dec 12, 2006 5:20 am

Maximous wrote:i was in OD, i was sitting at like 2500, i think, but i was noticing today that i cruise around 2000 so not much difference

I bet the throttle angle was a good bit more, and it kicked down more often.....Resulting in poor milage.

if you want something that gets good milage while towing, go buy a diesel 2500. The crew simply won't get good milage while pulling a load.

DLP · Post by **DLP** » Wed Jan 17, 2007 4:43 pm

I realize this is an older post. Haven't been around for a while. I have a 8x16' trailer with a pop-up and 2 quads on it. At about 3000 RPM and 65MPH in Drive pulling 3950 pounds I get between 16 and 18 MPG. I might be just a bit off on the RPMs. But I write down every fill-up with gal, ode and trip info so I know the MPG is correct. I do know that at 75 to 80 the MPGs drop to about 12 to 13. It pulls fine but the motor is running pretty hard and I can only imagine what the tranny is feeling.

Post by **Walt** » Wed Jan 17, 2007 8:05 pm

I moved this past weekend, and on our trip to the new place, pulling a load, I went through a tank of gas in less than 160 miles.

My wife's brother has an '04 single cab Silverado Z-71, pulling a 12' enclosed trailer, my wife's father has an '02 Silverado 2500HD with the 6 liter V-8, pulling a 20' enclosed trailer. Then there was little old me.

I had a 16' tandem axle open trailer loaded down. The big enclosed trailer carried furniture, the 12' enclosed trailer carried misc stuff and clothes, and mine carried the girls playhouse (1000lbs), 800lbs of concrete mix, a load of landscaping bricks (probably upwards of 1000lbs), and misc other outside stuff.

I had a 10 minute head start on both of them, but my wife's father caught up with me (I was staying under 65mph, he was moving along at close to 80mph). So I got in behind him, and we kept a pretty good pace, at least until we made it to a ridiculously long hill. My brother-in-law never caught up in the "Z".

My father-in-law said he was surprised I kept up with him. He told me I needed to get my tranny and drive train checked after that. He was speechless when I told him that I had a fullsize tranny.

ludwis · Post by **ludwis** » Thu Jan 18, 2007 5:00 pm

Now I know who to thank for our high insurance premiums.

2kwik4u · Post by **2kwik4u** » Fri Jan 19, 2007 11:31 am

Walt wrote: He was speechless when I told him that I had a fullsize tranny.

Great story, but please tell me you have an external cooler on that "fullsize tranny".

That is by far and away the first mod I will have done to the truck before I tow anything any further than across town. I saw tranny temps near 210-215 just driving aggressively while datalogging shortly after I bought the truck. The 60E likes to be closer to 175-180 for tranny temps, as I've seen.

In the end any truck that does ALOT of towing, I would suggest an 80E conversion when the time comes to replace the weak 60E.

Post by **Walt** » Fri Jan 19, 2007 1:00 pm

Nope. Not yet atleast. I rarely tow anymore. Usually it's my open trailer and maybe a pair of four wheelers going to the next county once a month or so.

WVHogRider · Post by **WVHogRider** » Fri Jan 19, 2007 1:34 pm

He*l, on my last tank, I got 14.5 miles/gallon with less than 100 lbs in the bed and no trailer. I'm re-doing the miles/gallon with this new tank.

Maybe it's time for a tune up--- ~80K, might be time.

Fuel filter was changed over the late summer.

killian96ss · Post by **killian96ss** » Fri Jan 19, 2007 7:15 pm

WVHogRider wrote: Maybe it's time for a tune up--- ~80K, might be time. Fuel filter was changed over the late summer.

You only replaced that fuel filter because we gave you such a hard time for running the stock one so long.

If you are @ 80k and still using the original parts then I would recommend replacing all 3 pre-cat 02 sensors, cap & rotor, spark plugs, spark plug wires, and PCV valve (clean it real good with carb cleaner or replace it).

You should also clean the IAC valve, throttle body, IAT sensor, and MAF sensor.

How about the transmission filter, differential fluids, t-case fluid, coolant, radiator cap, gas cap, air filter???????????????????????????????

Steve

WVHogRider · Post by **WVHogRider** » Sat Jan 20, 2007 5:10 am

killian96ss wrote:
WVHogRider wrote: Maybe it's time for a tune up--- ~80K, might be time. Fuel filter was changed over the late summer.
You only replaced that fuel filter because we gave you such a hard time for running the stock one so long.

If you are @ 80k and still using the original parts then I would recommend replacing all 3 pre-cat 02 sensors, cap & rotor, spark plugs, spark plug wires, and PCV valve (clean it real good with carb cleaner or replace it).

You should also clean the IAC valve, throttle body, IAT sensor, and MAF sensor.

How about the transmission filter, differential fluids, t-case fluid, coolant, radiator cap, gas cap, air filter???????????????????????????????

Steve

Almost all too true. Yes, but I performed most of the work on the truck because of you guys giving me a hard time, or should I call it "advice". Fuel filter & the middle O2 sensor was changed this summer. Transmission filter & fluid changed at 35K. The K&N air filter, IAT, MAF & throttle body get cleaned at every oil change. Coolant was flushed/switched late this summer to the green stuff with a new cap. New gas cap as well this summer.

I never touched the drive train fluids, ignition items, PCV or IAC.

I like to do preventative maintenance, but I also have the mentality of "if it ain't broke, don't fix it". Sometimes I confuse myself. I'll look into the getting everything done, but winter has finally set in (it's like 10-20 degrees now).

I'll need advise on where/what the IAC valve is and possibly changing the t/case & differ. fluids.

WVHogRider · Post by **WVHogRider** » Tue Jan 23, 2007 6:49 pm

This past tank was 13.5 miles/gal, but some of that is due to utilizing the 4x4 high & low due to the snow and hauling people. I had to make several short trip (5-10 miles) for people in 4wheel just to be safe.

I'll ask my what is the "best tune up parts" ? in one of the other posts.