Ok. I drive my Ranger about 30 miles a day. Lately I have had to fill up every three days. Thats only 8 MPG if my calculation is correct. What could be causing this terrible gas mileage?

 

how are you calculating it?

 

worn suspension components, low tire pressure, super dirty air filter, dirty fuel filter, failed/failing oxygen sensor(s) (sometimes they toss a code, sometimes they don't), possible exhaust leak, super lead foot

Give some more specifics....

• how are you calculating mileage?
• do you have larger tires?
• when was the last time you changed your oil (including filter)?
• when was the last time you changed your air filter?
• when was the last time you changed your fuel filter?
• when was the last time you checked tire pressure or had your tires balanced and rotated?

 

Yeah, really?

 

(miles/gas input) / 2 ??

 

Im calculating it based on the miles driven divided by the gallons in the tank. If I drive 90 miles (three round trips to work) and have 13 gallons in the tank then that is how im calculating.

I have a K&N intake. I check the air filter regularly. I also check the MAF regularly. I do have a spindle lift w/ 33 BFG's. I have a si/do flowmaster. I had the oil changed about 2000 miles ago so I will be due in about another 1000. The fuel filter was replaced around 11000 miles ago. The tires were just balanced when they were put on about 4 months ago. I dont have a lead foot so I know that is not the problem, I dont even gun it at green lights. It is possible that there is an exhaust leak but I wont know until I put it on the jack Saturday.

 

That happened to me once. Turned out to be a hole in the gas tank. I figured that out when I filled it up and let it set for a few days. When I came back I had half a tank left. Might want to check you fuel tank and fuel system for leaks.

Does the exhaust smell rich?

 

Number one: youre odometer is reading approx 10% slower/less than you actually are going because of those 33's and I assume you don't have a calibrator or a tuner to correct for the tire change.

Number two: try out a couple tanks with Lucas Oil fuel treatment/injector cleaner. That stuff is the shiz!

 

plugs? wires? what was the stock tire size and what gears do you have?

 

Figuring on 13 gallons is faulty. take your milleage, divide the number of gallons it takes too fill back up by the mileage, and thats the actual (close) MPG. I have a 15 gallon tank, and I never put more than 14 gallons in on fill up. Also, as previously stated, bigger tires will throw the actual miles on the odo off a bit.

 

Ive tried the Lucas treatment the past few fill ups. I dont have a tuner. I was thinking about plugs and wires. I bought the truck 3 years ago with 85000 miles on it. It now has 115000 miles. God only knows how many miles those plugs have on them. I like to do all of my work myself but these plugs in the SOHC seem like a b*tch to do. If any one has any pointers on how to do them easiest let me know. I got under her yesterday to look at the pipes and it appears that the RTV sealant has worn away from where the y pipe meets the cats. If that little leak could be causing all of this then I would be happy.

 

take the plastic inner fenders out and go through the wheel well, youll be able to get to your plugs much easier.

 

Stop!!!

Before you try throwing money at it, WHAT DOES THE EXHAUST SMELL LIKE?

Most people's comments have been related to bad combustion, which would to un-burnt fuel in the exhaust which you might be able to smell. If it smells like the engine is running rich then you know that it's bad combustion. At 8 mpg I'm pretty sure you're going to smell it.

Stupid question: Is the check engine light on?

 

Definitely change the plugs and wires. They are a pain on any 4.0L, but doable. Just takes a little time to figure out how to reach them.

 

Thats not a stupid question, but no Im not throwing a CEL. The exhaust as far as I can tell is about the same. I will try to smell it again today as I leave work.

 

Putting plugs in are not a problem..I don't no why anyone would complain about it on the 4.0 I didn't pull the inner fender or tire or any of that. I don't think it's your plugs, you would have to notice lack of power or it missing.

 

Smell it when you start up and then after the engine is warm. This may give you a clue as to what's going on open loop (cold) and closed loop (warm) engine control.

 

Just a quick check that the CEL bulb is good. The CEL light comes on momentarily when you start the truck, right?

(Trying to chase something down, all the while thinking that the CEL hasn't tripped when the bulb has really just burned out could lead to a real head scratcher and a lot of wasted time)

 

Have you noticed a lack of power corresponding with the decrease in gas mileage?

 

^^Brings a good point. It may be possible that the check engine bulb is action burnt out. Does the light turn on when you turn the key to 'on/run'....just before you turn it to 'start'. Where all the lights turn on for a few seconds.

 

I dont get why people cant calculate gas mileage correctly. fill up the tank, reset the trip meter, drive for a while, fill er up again, divide the mileage by how many gallons you put in. that is the ONLY accurate way to figure it out. how many times a week you fill up means nothing... lol

 

Well. Im sorry that not everyone is a super genius like you! Wow you should be on the board of directors at some major university. You must be the smartest man alive. I cant believe they havent written a book about the smart *** who tells everyone else that they should know how to calculate gas mileage when it really hasent mattered to them before this.

 

The check engine light works fine. It comes on when I turn on the engine for the first few seconds and Ive got an entire led setup so it is super bright. Im still playing with it all. I checked the exhaust and nothing smells out of the ordinary. I have noticed a very low idle if that helps any in diagnosing it.

 

thats only if you have stock tire size...... or your spedo is corrected

 

8MPG......wow

Unless you have a 454 under the hood, that's some crap mileage. When I forst read this thread I was thinking "hole in the tank or fuel lines?"

But that would be a call for Captain Obvious...LOL