My 94 has the 3.0 in it, it of course like most of them hasn't gotten really good mileage. but at 240000 it's been good. Lately it has gotten worse, and when you stop somewhere and get out, you can smell gas pretty strong. Like raw unburned maybe. If you try to crank it again shortly after stopping, it spins a good many time before firing. Could it be an O2 sensor going bad? I'm not getting any codes or a check engine light.
Thanks for any input.

 

While this can be caused by a lot of things, it could be that you, duh, have a leak on the pressure side of the pump, and the fuel rail depressurizes quickly when you stop. The pump doesn't start until you start cranking, and it takes a second or so to re-pressurize the rail.

The important part is "leak." Which is the most likely explanation for smelling gasoline.

Use your nose and eyes to localize it. Several of us at this age have had a failure in the Fuel Pressure Damper on the aft right of the fuel rail, which slowly leaks. Use a brown paper towel (gasoline is so clear it's sometimes hard to see on white) to stick up in there; if it's wet, you've found it.

 

Could a bad Oxygen sensor cause a drop in mileage? If so the upstream or down stream one?

 

Yes, but probably not to the point where "you can smell gas pretty strong." It would be the upstream sensor; the purpose of the downstream sensor is to monitor the catalytic converter (if both sensors swing together, the converter isn't doing anything).

O2 sensors are sorta a maintenance item (at a certain age it doesn't hurt to change them out), but I would look for a fuel leak no matter what when you get a strong smell.

 

Ok thanks for the heads up!

 

My 3.0 has 185,000 and I was having the same problem and I was freaking out, it could be much worse than what mine was although all I did was a fresh oil change, cleaned my k&n air filter, changed the plugs+wires, and put max air in my tires. Does it smell like gas on long highway trips or just short trips of a few miles?