Diesel Mileage Update

[mcfly]

I haven't posted in a long time. Some might remember my rantings on the disparate fule mileage numbers between all of the folks here. Some averaging more than 20MPG and others, myself included, averaging around 14MPG.
Last Wednesday evening I changed my fuel filter. I had a half of a tank of fuel left so I did not fuel up prior to my departure. I filled up 200 hundred miles later and my average was 15.3MPG. I drove 440 miles more and again filled up. This time the average was 16.7MPG. I then drove 515 miles and again filled up. That tank I averaged 17.8MPG, by far the best ever since I have owned this truck. I have never done better than 16.4MPG.
I do not drive this truck like a Honda Accord. I drive the **** out of it 75-85 most of the time.
Any way, I guess changing the fuel filter was responsible for this?

-Rick

[Johnson]

What Brand fuel filter did you use? I have had the same BAD mileage as you. I will give it a try IT would make my day if it gives me the same results. average mileage 14.5

[hickcox]

You think changing the fuel filter fixed your mileage numbers! Well if you haven't already done it change your air filter to an oiled foam type filter. I never drilled my filter housing out (like most have), but I use an Amsoil brand and just changing that improved my mileage by 3mpg.

I drive mostly city and have been averaging 18-20mpg since the air filter change back in 2001.

[deerhunter7]

I have to agree with Hickcox on the amzoil air filters. I Swiss cheesed the air box also . Gained
1 to 2 mpg . Just changed the filter at 11,500 miles but that made no difference.. tongue.gif

[Johnson]

I have already tried BOTH the amsoil and K&N and neither gave any improvement, I have the same truck as mcfly and the best has been 16.2 secound tank and now averages 14.5 so I will be willing to try the fuel filter The JUICE seemed to pick mileage up some havn't checked it yet.

[hickcox]

You have to remember having a dually will automatically drag down your mileage some (the extra set of tires), so I've been told.

[afp]

I wonder if these mileage gains (I experienced a 2 mpg increase in the first 2000 miles) aren't due more to the engine breaking in than anything else. I'm told if you work your truck hard, you can get it broken in in 10,000 miles. If you don't work it much (like me right now--no counting the full-throttle juice runs), it will take about 20,000 miles.

Blaine

[Idle_Chatter]

Mcfly, I know it will be difficult, but just for argument's sake, take it down a notch or two and try driving a tankful at 55-65 miles per hour instead of 75-85. I think you'll be surprised. These engines seem to *love* to run 55 and some of the best mileage that I've scored (21 mpg) was on a back-road detour all night one night were I had to keep it around 55. I get high 18's to low 19's driving 60-65 on the interstate. Your heavy foot could be one big factor in your low mileage. Worth a try, anyway.

[dmaxster]

well with 35,225 on now and hope to have 35,800 on by the end of the weekend......but anyways....I have gotten as good as 21.9 when I went down to Indiana.....but have gotten as bad as 14 all with out towing.....with towing I have gotten 12 but also as low as 9 so it depends on conditions and how aggresive you are I guess.....but the average is 18 mpg.....this is empty and hwy/cty.....and I consider myslef pretty aggressive.......but I agree with Idlechatter and the truck does like the 55-60 range and is where i get the best mileage......however when I went to Indiana it is all interstate so that also helps....no starting and stopping.......Dmaxster. :cool

[vince]

I took a trip from Whitehorse, YT to Anchorage, AK a couple weeks ago, about 1500 miles. Here are my fuel stats thanx to a metric converting calculator:
12.3 liter per 100 km.
19.1 mpg US gal
22.9 mpg Imp gal

I was running about 110 klicks or 65 mph.

'01 2500 dmax/allison cc sb

regards
vince

[gdblake]

My truck has 8300 miles on it--the last 6200 pulling a 9000 lb 5th wheel trailer. Driving 62-65 mph with the trailer, I get 11.7-12.4 mpg. Pulling the trailer at 75 mph--10.5mpg. Typical mileage empty at 65 mph is 19.5. Driving one time at 50-55mph on the hwy--no stops--27.3mpg.

[62dog]

vince

I am getting identical mileage to you with identical truck and driving speeds. Even my conversions works out the same. My truck has less than 3000km on it, so I am hoping for a slight increase in mileage as it is broken in.

[GMC-2002-Dmax]

I have kept a record since new, I now have 11,300 miles on her. These are all of the numbers

First tank 16.87, 16.81, 16.38, 16.30, 16.74, 16.81 at 2000 miles.

16.81, 16.99, 16.64, 17.54, towing 6000 lbs 15.78, 17.81, 18.12, at 4000 miles.

17.33, 17.89, 18.33, 17.96, 18.35, 17.48, at 6000 miles.

17.18, 18.20, towing 6000 lbs 14.77, 17.78, Juice installed L4 18.01, 17.55, 17.87 at 8000 miles.

17.27, 17.10, 18.33, 16.38, 17.48, K&N Filter added 18.21, 18.32, 17.33.

I drive about 70% city and 30% Highway. My right foot get's quite heavy and I avg. 45-60 mph rural roads and 65-75 mph highway.

I am happy going from a GMC big block at 10-12 mpg empty to this. ;)

GMC :D

[RRHOGGER]

It is very unlikely that your fuel filter would affect your milage unless is was plugged bad enough to cause the high preasure pump to cavitate trying to pull fuel through it - if this were the case it would also cause drivability problems as well. What probably happened is you expected the filter change to make an improvement (an improvement that you badly wanted) and subconsciously made a small change in your driving. I have experienced this myself and have seen it happen with many customers. I think you get great milage for the way you drive! I drive hard myself and often get 20 to 30% poorer milage than my wife who never goes under the limit. :D

[TBC]

smile.gif My 01 D/A wheel drive ext cab short box has 16,300 miles and on the last tank (with aux tank) I drove 920.8 miles with the most of it city driving. Some hwy driving was mixed in but not more 200 miles on country roads. I got 15.55 MPG and this was all us air cond. I am a let lead footed at times. I have averaged over the life of the truck 13.4 MPG with towing a 8800 lb TT, city, hwy and all. I had a 4X4 w/454 Suburban and could not get 13.4 consistantly on the highway empty. I am well pleased with this truck. BTW it is running better now than ever and is stock except for a K&N and I drilled the air box Saturday. Except for a fuel manifold leak and busy shifting this truck has been flawless. Love to drive this truck.