I know..i know...there are a bunch of topics....but im getting 6-8 MPG!!! HELP!!

[riffman]

Like i said..i know that there are a bunch of these topics out there, but i can't seem to find the right stuff that i need to do in them.

Heres the scoop. 6-8 mpg, anywhere i go....highway, in town, blah blah blah. the only thing i have really seen to change is the o2 sensor. What else do i need to change? the filter has been changed....but do i need a new ingition sensor?

heres the specs on my truck.
92 xlt
4.0 L stock
5.5" stupid lift up front
custom soa in the rear
2" body lift
it was on 35" dunlop mud rovers
3.73 gears

im in the process of swapping in a dana 44 but would like to get the engine better before i finish the swap.

HELP!! anybody? What needs to be changed?

 

[GJarrett]

Fuel Pressure Regulator would be the #1 suspect. In addition to that, also try searching for it under its abbreviation FPR.

[Edited by GJarrett on 01-15-2001 at 12:42 PM]

 

[mattadams]

and if its not the fpr, get a locking gas cap, maybe someone is siphoning you . A few other things to check...
Air filter, sounds stupid but if this is incredibly gunked up, the engine will have less air and as a result, less power... to produce the same amount of power as usual then it has to work much much harder.
While your doing the air filter, check your air intake, pull it off and check the throttle body as well. Look for any crud. Despite the fact is says not to clean it, use some air intake/throttle body cleaner and get some of the grime out. if theres a lot of gunk in there it oculd also be related to bad filter or bad air intake line...
Spark plugs

I don't think either of those could bring you down to 6-8mpg though... so check the fpr and get a locking gas cap .

 

[riffman]

wow!! those were some seriously fast relpys!!! where exactly is the FPR?

 

[Ira]

Start out with a compression test. If all seems to be good, look at the FPR next. If you are only getting 6-8 MPG, I would guess that the FPR is either stuck, or has a hole in the diaphram. If you want to eliminate this totally, buy a fuel pressure gauge that hooks into the Schrader valve on the fuel rail and test the pressure. I got mine at AutoZone for about $30.

You didn't say anything about a check engine light. Generally on this model, the O2 sensor has to be defective before the light will come on. The sensor will usually go bad shortly after the FPR because the increased amount of fuel tends to clog up the O2 sensor and will not allow the reading to get to the computer, thus the Check Engine light.

Another possibility, stuck brake caliper. I know it is a long shot, but if you get one stuck it will also affect the MPG. You can check this out by raising the front end and spinning the wheels by hand. You will quickly be able to tell if it is stuck due to the increased effort to turn the wheel. Then proceed to the rear and check them.

My money still lies on the FPR. Don't expect to get 20 MPG with your big wheels. They will also affect your MPG. Also, if you have not recalibrated your speedometer since adding the bigger wheels, you may want to do that. This will also change your MPG as the mileage is not right with a speedo that is out of calibration.

[Edited by Ira on 01-15-2001 at 12:49 PM]

 

[mattadams]

Originally posted by riffman
wow!! those were some seriously fast relpys!!! where exactly is the FPR?

It's a pain in the butt to change that's what it is! Basically it just says how much fuel to send to the engine... have you noticed a different colored exhaust or any check engine lights or anything? Those are often symptoms of a bad fuel pressure regulator...

 

[riffman]

the only light that is on sometimes is the check oil light..no check engine, nothing like that...

 

[Ira]

It took me less than an hour to change mine out. The FPR on mine, is on the front passenger's side of the intake manifold. Look for the fuel line (mine has a braided steel cover) coming into it and then it goes into the fuel rail. It should also have a vacuum hose connected to it to operate the FPR.

 

[Dennis Myers]

Hey Riffman,
You could leave your 35's on the back and put 32's on the front and coast down hill every where you go that would help you fuel milage.
Check your FPR and O2 sensors like everyone has said.

 

[Dennis Myers]

One more real thought, have you corrected your speedo for the tires and gears? If not you might be getting better or worse milage than you think.

 

[Brian1]

Originally posted by Dennis Myers
Hey Riffman,
You could leave your 35's on the back and put 32's on the front and coast down hill every where you go that would help your fuel milage.

Go downhill all the time! LOL!

 

[riffman]

actually...believe it or not..i already figured that in!! i figured out the actual circumfrence of the tire, and based that on my mileage...its not as bad as i thought it would be...its only adding 1 tenth for every mile.

 

[Jdog25]

http://www.explorerforum.com/forums/showthread.php?threadid=23984