Recently i have gotten my truck looked at by a mechanic because i am getting 6.3 miles to the gallon i can't figure out why. they did some stuff but it did'nt help still getting bad gas mileage i believe it is supposed to get at least 12-14 on the highway.

 

What's the question?

 

Is there a Check Engine Light? Test Fuel Pressure.

 

How's it run first of all? Transmission? Miles on the truck? When did you notice the drop in mileage?

One thing I found out that really helps mileage, is to disengage the parking brake when you drive. just kidding.

 

I have a ford 1996 f250 5.8 liter, its got 82,000 miles on it, and i am getting 6.3 miles to the gallon last time i checked. any suggestions. gotten checked by mechanics twice couldnt figure it out. But if you drive about like 15 miles the the check engin light goes on but when you shut off the truck it shuts the check ingine light off too.?

 

Well, if the check engine light goes on, something is wrong.

Get the error codes out of the computer, and find out what is wrong. Could be 20 different things, us guessing with essentially no information is just going to waste our time and cost you money.

Follow this simple picture, then look at the codes list below:

http://www.midimonkey.com/~frederic/f350/eec-codes.html

The connector is under your hood by your driver side hood hinge. Jumper the two connectors as shown, then put the key into the ignition, and turn to "RUN". Not start, not acc, RUN.

Then watch the check engine light blink, and count the blinks.

Viola, there's your first code.

Turn off truck, turn back to RUN, watch blinking, get second code.

Etc.

 

well my truck is a 93 f350 with speed density. i just put a new engine in and am converting to mass air... however my old engine did the same thing it turned out to be a bad o2 sencor and cat converter..... i replaced the cat with one from summit(MUCH CHEAPER THAN ANYWHERE ELSE AND DIRECT FIT)

 

For 6.3MPG it really sounds like the Fuel pressure regulator is stuck closed.

 

What "stuff" did "they" do?

 

they did a tune up and and some other stuff but that is it..

 

We cannot help you unless you provide us with more information. It's that simple. People are repeatedly asking you for more detailed information, and you're not giving it.

 

its a 1996 ford f250 5.8 liter 4x4 xl singal cab

 

then now its been acting up even more when i start off it will like bog down and work the enigine hard but it won't have power then it has power it like kicks in and out like something is holding it back idk...

The check engin light goes on after you drive about 5 miles but the it shuts off when the truck shuts off? that something else to.

 

I don't know what you want from us. We are all more than willing to help, but you won't give us the information we need to do that.

Pull the codes. Tell us what they are, and we'll help you fix them until they are gone. If you're still having mileage and drivability problems, we'll help you fix those too.

But we can't help you unless you're willing to help yourself. So far, it looks like you're not.

 

If you're unwill/unsure of pulling the codes yourself, call your local parts stores and see which will ones will pull your codes for free and let them do it. While there, see if they'll check your fuel pressure too.
Cheers,
Popa Tim

- and get a new mechanic. Anytine the Check Engine light comes on, the first diagnostic step will be to pull the codes and see WHY the computer turned it on... this one just raked you for a tuneup.