Fuel Mileage

[Danoflapper]

Today I filled up and checked my fuel mileage for the first time. I was hoping it'd be 17-20. Turns out it was 12.4MPG. This is all country roads too. 5-10 miles of 1500RPM cruising in between stop signs. After hearing some of you guys getting 20 MPG or better I'm kind of surprised to see numbers that bad.

I don't drive like a maniac but sometimes it'll shift at 2300ish. I think my tiny tires are wrecking my fuel mileage. But then again I'm moving almost 10,000LBS of steel.

For this next tank of fuel I won't let it rev over 1600 and see what my mileage is.

So my question is: Are the tires hurting my mileage that bad? And am I really getting substancially better mileage but the small tires are screwing up my ODO readings?

Thanks ahead of time.

 

[razorback]

use any additive or anything?

 

[DragRag]

I'd say yes, those tires are dinky. Get 235/85r16's for the best mileage. Sounds like your truck is not running that efficiently either. Air filter plugged, or timing way, off, or injection system may be worn out, and out of time.

 

[Danoflapper]

Additive - I use a quart of ATF every fill up.

As for the tires, I don't like them at all but they have a bunch of life left on them so I'll use em up.


The air filter is relatively new. Just a Fram paper one with some foam underneath it.

It could be out of time, It seems to start up nice though. My parent's records show it had a remanned IP 45K ago. Not sure about injectors though. If I take a video of it running will you guys be able to tell if it's in time?

I take it that I shouldn't get such awful mileage on just the tires alone?

 

[Shadetreemechanic]

I think you will see a difference shifting at 1600 instead of 2300.

 

[FordGuy100]

Like said above. Taller tire, fuel additive, freshen up the fuel system (IP rebuild/re-time, new injectors), and you should be golden.

 

[93cc7.3]

plus gravel roads dont help any kinda like driving on half inflated tires

 

[Brianedwardss]

Yeah 12.4 is definitely low but not unheard of. I only get 14, got 15.1 once.

 

[DragRag]

You would be doing yourself a favor by finding those taller tires used or something, your tires are really undersized. The sell your to recoup some of the cash, you'd be much much better off.

 

[Danoflapper]

I think you will see a difference shifting at 1600 instead of 2300.

I highly doubt it will bring me from 12.4 to the 17 range considering there aren't many stops or starts.

Like said above. Taller tire, fuel additive, freshen up the fuel system (IP rebuild/re-time, new injectors), and you should be golden.

I can probably do the bigger tire and for sure the additive. I can't afford to do an IP right now. Injectors are possible. I really would like to put my money into fenders/box/bumper and a pyro/boost gage.

plus gravel roads dont help any kinda like driving on half inflated tires

No gravel, just two lane blacktop.

Yeah 12.4 is definitely low but not unheard of. I only get 14, got 15.1 once.

:O I'd really like to get into the 20s club.

You would be doing yourself a favor by finding those taller tires used or something, your tires are really undersized. The sell your to recoup some of the cash, you'd be much much better off.

I'll start searching craigslist. I got the set that's on it for $300 with the alcoas. I definitely won't put 235s under it if I'm going to get new tires. probably 265s or 285s That probably defeats the purpose of getting different tires though.

Can you guys tell if it's timed correctly by hearing it through a semi-decent video? I can take one tomorrow.

 

[FordGuy100]

It will probably help if you can take a video of it, compare it to our trucks to see if the timing is good.

 

[ericboutin]

With mine I used to get 11 to 11.5 consistently no matter if I was towing or not. I slowed down a bit and I get slightly better than that. I don't know what gears you have but if you are really pushing 10,000 lbs then 12.4 maybe pretty good....

 

[Danoflapper]

It will probably help if you can take a video of it, compare it to our trucks to see if the timing is good.

Mm'kay will do.

With mine I used to get 11 to 11.5 consistently no matter if I was towing or not. I slowed down a bit and I get slightly better than that. I don't know what gears you have but if you are really pushing 10,000 lbs then 12.4 maybe pretty good....

I've got 3.55s All the miles were empty. I just figured the truck weighs 8kish and rounded up for effect haha

Who knows, maybe I'll be stuck under 15MPG

 

[trapper]

do you mean you are putting Automatic Transmission Fluid in the diesel? as im new to the additive stuff

 

[Diesel Max]

On my 92 F250 4X4 with the E4OD and 3.55's I was getting 20 mpg on the hwy running 70-75 MPH. Most of my driving is interstate.

On my 93 F250 4X4 with the ZF5 and 4.10's I'm getting 15 mpg on the hwy running 70-75 MPH.

Gears play a huge part in MPG..........