Hey everyone, I'm new on here and hoping ya'll can help.

I have a 98 ranger with the 4.0L OHV. Its my daily driver but I let a friend borrow it the last few weeks becuase her car had no A/C. I fixed her car and got my truck back yesterday. I filled it up, drove it, and it sucked down a quarter tank of fuel in only 18 miles on the highway. I dont notice a nasty smell from the exhaust as if its the cats. Thers no check engine light on. It doesnt seem to be under powered. Maybe a leaking injector. I dont smell fuel nor do I see any leaking.

Any thoughts??

 

I would pull a spark plug and see if it shows rich fuel mix.

Your '98 would have the higher pressure "returnless" fuel system.
You would need a pressure gauge to test for leaking injector, 50-60psi would be expected pressure with engine off.
The returnless fuel system doesn't have a fuel pressure regulator on the fuel rail but it does have a Pulse Damper with a vacuum hose attached.
These rarely fail but if they do leak the vacuum line is there to suck any leaking fuel into the intake to prevent a fire.
Remove this vacuum line and check it for fuel or fuel smell.

MAF sensor is the main sensor the computer uses to set fuel/air mix, this sensor can get dirty over time which effects MPG, but not usually in a few weeks.

 

as per what RON said

also check the spark plugs , probably need new spark plugs

i would also ask your friend what brand / octane of fuel she was filling the fuel tank with

always re-fill your fuel tank with the same brand / octane of fuel

 

I have a 2008 XLT 4x4 and I try to buy non ethanol at a fuel dock where my dad works, but due to my job I sometimes can't make it their in time before running out of fuel. I find that the non ethanol fuel is more fuel efficient than say regular "gas station'' fuel with ethanol. Try non ethanol fuel if this is available to you. Hope this is helpful.