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Ford Explorer Getting Poor Fuel Milage

Q. I'm having trouble with a 1993 Ford Explorer. I am getting poor gas mileage (11 to 13 mpg) average city & highway. Truck got 16 mpg in town and 21 to 23 mpg on the highway when it was new. I change the oil regularly and recently changed the plugs (OEM), fuel filter (NAPA), air filter (K&N) and the two 02 Sensors on the exhaust system.

Ford Explorer Getting Poor Fuel Milage

The injector O-rings were leaking externally onto the intake and were replaced last month. Compression on all cylinders is fine. When I start the truck in the morning it seems to breathe easy and has plenty power and sounds and drives normal.

After 15 to 30 minutes of driving on a hot day and after the engine has warmed up the truck seems to have a power loss of 10-20%. It is also hard to start after I have been driving for a while, stop and get out for a few minutes and then try to restart. Almost seems like starter is weak or the engine has a vapor lock.

The starter has been tested to be fine. Battery checks okay also. Seems like the fan clutch gets louder as the truck gets hotter. Engine temperature gauge has never gone completely to the red zone but somewhere around the "AL" in NORMAL on the gauge.

At the recommendation of a "ASE" certified mechanic, I changed the coolant temperature sensor for the ECU last week but it didn't help. I have smelled gas through the A/C vents for a while, at least six months to a year. Thought the O-ring job on the injectors would have solved this because there was visible gas on the intake. No more gas on the intake but still smell inside truck.

The local mechanic seems to think there is a bad sensor somewhere making the injectors flood out the cylinders. He hasn't pulled a plug yet to see what they look like but will do so the next time I can drop it off.

He put the truck on the diagnostic computer Wednesday 7/09/03 and it gave him two codes. He said one of the codes was undefinable and I'm not sure what the other code was. He said he didn't have an answer for me and would have to spend more time on it at a later date.

My questions are: Are there any known problems similar to mine and what was done to solve the problem? What else can I/we check to determine the nature of poor gas mileage, power loss and smell of gas? I would appreciate any help or advice you can offer.

  • 1993 Ford Explorer Eddie Bauer 4WD
  • 4.0 liter V-6
  • Automatic transmission
  • 147,000 miles
  • Fuel Injection
  • ABS
  • P/S, A/C, Cruise control

Ford Explorer Getting Poor Fuel Milage


A. The first thing I would suspect is a faulty/leaking fuel pressure regulator. When the diaphragm develops a hole or tear in it, fuel passes through it and the vacuum line sucks the fuel into the engine which would result in your drop in fuel economy, loss of power and fuel odor, and hard starting when hot.

You can easily check the regulator with a manual vacuum pump. Connect the pump to the vacuum port of the regulator and draw it down to 15 inches, it should hold for a minimum of five minutes if no leaks are present.

If you see fuel when you unplug the vacuum line, the fuel pressure regulator is bad.

Ford Explorer Getting Poor Fuel Milage

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© 2003 Vincent T. Ciulla

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