ok brain picking time again! '95 3.0 auto 4x4 4/3 double lift open diff 3.73 stock gears

ok just got the suspension lifted 4 inches but the gas mileage was way down before the lift. just rebuilt the top end with ds new head, due to broken bolts and threads broke off spark plug!

when i first got the truck, i was getting 21mpg now im around 10mpg, i do a lot of long distance driving!

at idle i can feel the miss, in town or at highway speed (around 70-80mph) she runs like a sewing machine on crack! no codes, and over time the only things i haven't replaced are the coil pack and the maf!

what are your alls thoughts and suggestions?
kobin

 

On engines fuel rail will be the Fuel Pressure Regulator(FPR), return fuel line is connected to it, and there is also a Vacuum Hose connected to it.
Remove vacuum hose and check it for gasoline

If FPR leaks, raw gas will be sucked into intake, MPG will go down and power will be GREAT, extra fuel, but if leak is big enough you should get Rich code

Another thing to test for is leaking injector
Turn on the key
Press gas pedal to the floor and HOLD IT DOWN ALL THE WAY.
Try to start engine

It should not start and should not even fire.
Gas pedal to the floor at 0 RPMs(Engine off) tells computer to start Clear Flooded Engine Routine
This turns off fuel injector pulses until gas pedal is released
So there should be no gasoline going into engine so no starting and no firing unless an injector is leaking(or FPR)

This "test" is also good to use on older engines, my 4.0l is at 400k and I do this every morning before starting, pumps up oil to the top of engine before starting :)
Pretty much every fuel injected engine has this routine in computer, not a Ford thing

 

ok no leaking injectors, next commercial ill check the fpr,nascar is on! lol

 

lol nascar is done. nhra is on but i did check the vacuum line to the fpr and no fuel!

 

also the power has not gained or lost any thing that i can telll

 

im fixin to drive 150 miles tomorrow and i barley make it on a full tank of gas

 

If engine is not running Rich then you are losing gas, maybe from filler tube, check it for fuel smell.

Or check neighborhood kids, lol, if they are not greedy they can siphon a bit every few days, you won't notice except when you check MPG............WTF!, 21 down to 10?????

 

thats what im sayin ron! i expected to loose some milage when i did the suspension lift and bigger tires, but i think 11 mpg loss is telling me there is some thing not right or happy. i just replaced the plugs and wires again and the ruff idle is still there. all the plugs looked fine

 

Have you compensated for the odometer/speedometer change with bigger tires?

odometer will be setup for stock tire size, so with larger tire diameter vehicle will be traveling farther on each revolution of the axle or drive line
So if your using odometer as baseline for miles traveled it will be off, as will speedometer
If odometer says you have gone 150miles you may have actually gone 180miles, if you used 10gal then not 15MPG but 18MPG

 

brain fart, i forgot about odometer being off as well as speedo! speedo is 7 mph slow so if my thinking is right, if i drive 2 hours , i add 14 miles to odometer. am i right in my thinking?

 

yes and no, lol.

It varies by speed, your speedo can be off 5MPH at 40mph, and then off by 8MPH at 60mph, same tire size, so odometer would vary like speedometer does

Calculator here: https://tiresize.com/speedometer-calibration/

So depends on "average speed" and won't be as precise as regearing speedo hookup.
1997 and earlier Rangers still used a gear in transfer case(or trans) for speed signal

Rangers used 8 tooth DRIVE gears, I think, the DRIVEN gear is what you change, they are color coded
See what color gear you have now and then use stock tire diameter on below calculator, that will tell you if you have a 7 or 8 tooth DRIVE gear on the output shaft

Look here: Speedometer Gear Calculator and Charts - TCIŽ Auto

 

rotf if the neighbor hood kids can run o-80 mph then they can take the gas, because i fill up just before the interstate. my gps app says my average speed is 70

 

There are free odometer APPs, that would be good baseline to do MPG until you change the gear