I just bought a 2003 XLT Ranger with 4x4 and 140,000 miles on it a week ago, but have been averaging 11mpg on the last tank with even city and highway driving.

The last owner did the following work to it in the last 20,000 miles:
-New timing chain kit
-Water pump
-Full engine gasket set
-Spark plugs and wires
-Oil change
-Coolant change
-Knock sensor
-Head bolts
-Alternator
-New muffler

He was a mechanic and did all that work himself - any guesses on why it’s still getting such horrible MPG? He claimed to have gotten 15-18mpg up until he sold it to me.

 

Welcome to the forum

Check odometer if thats what you are basing the MPG on

You can try GPS for speed and odometer testing

One tank is really not a good test

You can pull a spark plug or two and see if its tip a darker color, Rich running
If not then you would be leaking fuel from somewhere

Yes, 15-18 MPG would be optimal, 11MPG means something is wrong, with calculation or fuel system

 

thanks for the reply! I checked the speed and odometer with an app on my phone, speed was maybe off 3-4mpg but odometer was dead on.

I’ll do more fill ups to test it but if I’m leaking gas would I always be able to smell it?

 

If its leaking out of the tank it could be, there could be some emissions issues along with it that just havent shown up on the PCM yet, you could of course take it to an autozone and see if there are any pending codes.

Does it feel like its down on power or straining?

 

I just calculated a tank of highway only miles and averaged out to 11.8mpg (nearly the same as city driving too). I ran the codes and there was nothing that popped up. No noticed loss of power or anything else out of the ordinary. Other than the low MPG, the truck runs great.

The previous owner put a new muffler on right when he sold it to me, could that have anything to do with it?

 

No, new muffler is fine, you would notice a power loss if it wasn't

As said check spark plug tips

There is only two ways gasoline can leave your vehicle, thru the engine to make power, or from a leak, thats it, simple really

Well there is a 3rd way, siphon hose at midnight, lol.

In the winter you won't always smell gasoline, test is when you are filling up the tank, do you smell it, or do you have to TRY to smell it, a small leak won't smell much in the winter time, temps under 50degF

 

At what average speed, anything over 60 MPH is going to hurt your mileage, 65 even more, 70 even more.

With mine, 55 to 60 on a 250 mile round trip, I average 15.6 mpg = able to do trip with stopping for fuel.
Exact same trip with cruise set at 65 = 13.7 mpg = have to stop 30 miles from home for fuel.
Exact same trip with cruise set at 70 = 11.2 mpg = have to stop 80 miles from home for fuel

 

Complete guesses these.
Injectors spraying too much fuel? Does the oil smell gassy?

 

I own a 2004 4.0 4X4. I drove it for a couple thousand miles and was getting
19.5 mpg. Then my mileage started to decrease. At 16.5 I started doing research.
After buying a scanner and reading up on the vehicle for a month i could find
nothing wrong. Then I found an article that suggested that if i disconnected
the ground lead from the battery and used aligator clips to ground the
disconnected lead , that this would discharge the capacitors in the
Power Train Control Model and allow it to reset .

It Worked!!! But I am having to do this more frequently and ford no
longer produces these modules.