New member here lookingfor some input.

I've got a 94 F150 5.0 5 speed manual 4x4 that has 157k on it. The truck is mainly used for yard work and getting around in the snow.

I've recently noticed that the check engine light is on, and it seems the fuel economy is waaay worse than it used to be. It used to get 15-18 mpg, but now it takes about 1/2 tank to get to work and back home, putting the mileage at less than 10 mpg...more likely around 5 or 6 mpg.

The truck is not driven often, so I can't say the CEL coming on and the fuel economy issue happened at the same time. Also, I've noticed a whistling sound from under the hood that changes in pitch, and sometimes goes away. I'm guessing a vacuum leak. I haven't run scans or checked codes.

Any advice on what could be happening, based on the limited info I've provided would be appreciated. It's been recommended that the fuel pressure regulator may be bad...just from talking with another guy who had a very similar issue with his 90 Bronco 5.0.

Thanks in advance.

 

You need to read out the CEL codes. Without those you would just be guessing. You can do this with a EEC-4 code reader or by using the "paper clip" method.

 

Go to www.fordfuelinjection.com to walk you thru the CEL check with a paper clip. The whistle is most likely a vac leak and it could take a little to find without first checking the CEL.

A tune-up may be in order. I would also clean the TB, IAC valve, replace O2 sensor(s), install new Motorcraft or Autolite copper plugs, a good set of low resistance plug wires, MSD cap & rotor, a new ignition coil and a new fuel filter.

The 5.0L wasn't known for great mileage but you can perform the above to help out with performance, driveability and a mileage increase.

 

I'm sure the light is on for a reason, fix that, get a driver mod and your mileage might increase

 

The quickest & cheapest EFFECTIVE way to raise MPG is to raise your tire pressures. Go as high as you can tolerate, up to the max molded into the sidewall. Read these captions & follow the links in them:

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