My 98 B4000 has started to get poor gas mileage. It went from about 18-19mpg in town to around 15.5 to 16mpg. It has around 90k miles on it now and about all I have ever done is changed the oil and put gas in it.

I know it is probably due for a tuneup. Plugs, wires and a fuel filter. Where is the fuel filter on these vehicles? Any special tools to replace? I have the fuel line/AC disconnect tools that I use on my 89 Mustang GT. Replace the O2 sensors as well? Hopefully there are just two and not four. $60+ a piece gets expensive after 2.

Thanks
Casey

 

Sounds like you have a good plan. The filter should be on the frame rail under the drivers seat, with a shield. You will need a special tool but I'm not sure which on works on the 1998s, does anyone know what needed for that year.

 

At 75K, I did plugs, wires, air filter, and fuel filter on my '99 and picked up 2 miles per gallon. Also keep in mind that cold weather will cause some decrease in fuel economy.

My '99 had three O2 sensors, one on each bank and then one between the catalytic converters. They do make removal tools for fuel filter and O2s, most auto parts stores carry them.

 

Thanks guys. I kind of thought that the cold weather might have had something to do with it. I'll look at the fuel filter and see what it takes to get it off. I have several of the A/C and fuel line disconnects so hopefully one of those will get it off.
I'll change the plugs, wires, fuel filter and air filter as soon as it warms up a bit. O2 sensors if I feel rich......

Thanks
Casey

 

Do everything else before the O2 sensors.

The sensors get the air-fuel mix and the computer reads that. Nothing more.

If you've got injectors running lousy or something like that, all you're doing is applying a band-aid to a fracture, so to speak.

As mentioned, winter fuel mixes suck for mpg's.....try said tune-up first.