7.3L getting poor gas milage

[Tail_Gunner]

.... I have gone 79 miles on 1/4 of a tank of diesel....

Don't be too quick to judge. You need more than 1/4 of a tank to be able to make a determination of fuel mileage.

My gauge will not come off the full peg and drop to the "F" mark until I've used 9-10 gallons. Half full by volume equals about 5/8 on the gauge. The gauge drops faster from the "F" mark to 3/4 than from 3/4 to 1/2 and so on.

Get a tank full or two before deciding if your mileage sucks or is closer to average.

 

[aklim]

I seem to only be able to fine the ULSD and the B10 around here. I will try the B10 next time. The truck is currently at best buy to get a security, remote start, and keyless entry system put in.

ULSD is the new kid on the block. Actually, it is the ONLY fuel you have commercially. You may lose a little mpg but it is not a lot. Personally, I haven't lost even 2 mpg. It is one and some change.

 

[ajchuck]

Well I like to fill up at 1/4 of a tank so I know it is not about to run out on me. Is there a good time to fill up to go longer? Does anyone's 7.3 shift at 25,35,45 MPH??? I am not wondering if the other owner messed with the settings as well.

 

[aklim]

Well I like to fill up at 1/4 of a tank so I know it is not about to run out on me. Is there a good time to fill up to go longer? Does anyone's 7.3 shift at 25,35,45 MPH??? I am not wondering if the other owner messed with the settings as well.

The impression you gave is that you fill up at 3/4 tank and it went 79 miles. If so, that is hard to get a mpg. When I calculate mpg, I fill the tank till I can see the fuel and I rock the truck to burp it. What is your mpg at the end of the day. BTW, we don't trust the overhead console too much. It seems accurate enough if I were to leave the PCM stock but I don't do that. I'm not too sure the shifting has that much to do with your mpg. However, those seem like decent shift points.

 

[ajchuck]

It seems a little high to me since I am coming out of a duramax. This truck was pulling a good size trailer before I bought it so it is set up to tow. It has air bag suspension so other things can't be stock.

 

[Sleeper Diesel]

3.73 or 4.10 rear end gear ratio that will make a different. my firends duramax has 4.10, my 250 has 3.73 that will affect the rpms when cruising.

 

[FJK]

Don't panic just yet. You have not even run through a tank of fuel yet & are just going off the gauge. Remember, due to the fuel tank filler inside the tank, the fuel nozzle clicks off early due to fuel foaming. If you want to spend the time, you can squeeze another 4-5 gallons of fuel into the tank. What that means is, depending on how you fuel, "full" can be inconsistant relative to a "full" gauge reading. So, fuel consistantly & record the mileage, then do the math. Also, since the injectors are driven by engine oil, stay on top of your oil changes.

 

[orion_134]

For those of you that haven't done the in-tank mods....do them!!!! Mine fills up to the same spot, everytime, the first time. I can only milk in another 1/2 gallon once it clicks off.
Jesse

 

[bears4x4]

mods

what in tank mods

 

[CHPMustang]

We'll get ya'll up to speed Bears

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