ford ranger and missing gas

[Seanz0rz]

so i have a buddy, has a 96 ford ranger with the 4.0L pushrod engine. the last month or so it has been missing gas. he gets excellent highway mileage, just like he always has, (22mpg) but lately his city mileage has been around 10mpg, unusually low for a 5spd vehicle, and significantly lower than what is typical for him. he also notices the fuel guage significantly lower after it has been sitting a while.

so he is losing gas while it sits. it is not "leaking" in that its not dripping on the ground. there are no CEL's, which he had last year when he had to have his filler neck replaced because of it being cracked.

so my thought is either fuel being dumped through a start injector or other fuel line (i havent had a chance to look at the vehicle, thats in about 45 minutes.) or it leaking through some portion of the emission system. again, no codes, so the vac. in the tank is being maintained.

so do you guys have any idea? hopefully someone here has had a similar experience on another vehicle, and can give me some tips where to start, what to look for, etc. thanks guys!

[corax]

someone siphoning gas when he goes urban?

to find out if an injector is leaking -> if you have a fuel pressure gauge, hook it up, start the engine and shut it down - make sure fuel system maintains pressure - it will slowly leak down after a while, but should maintain, within 10psi, for ~10-15 minutes. if it drops fast, there is a leak - pull the fuel rail/injectors and watch to see which one is dripping

[slosurfer]

I wouldn't go by his fuel gauge, my '96 Mazda truck (same as ford) the gas gauge only worked for a few years. I've run into many with funky gas gauges in those years.

Is he measuring by how much gas he is actually putting in and keeping track of what the mileage is each time he fills it up or going by what his gauge is saying?

[Seanz0rz]

im assuming (like 99% sure) that he is measuring by what he puts in. just noting the fuel gauge moving while he is away to point out that its disappearing while he is gone, not that hes getting really bad mpg (which would indicate other issues, like running rich for a multitude of possible reasons.) he should be here shortly so if there are any changes, ill post up. otherwise im just going to check for cracked/broken lines and whatnot, the usual stuff. dont really know how to even go about diagnosing the problem.

[Robinhood4x4]

I got poor city mileage when my AFM was bad.

A bad O2 sensor will worsen mileage too, but typically trips the check engine light.

[Seanz0rz]

well we dropped the tank, possibly found a hose that might have been disconnected, not sure. checked the tank for cracks, etc and reinstalled it...


all i have to say about that truck is i want to blow it up. i hate ford and it makes me so glad i own a toyota...

[4runnerchevy]

The Ford is probably better off without gas in it. They run better that way. :flipoff:

[04 Rocko Taco]

Sean, its like I've always said, the best thing about Ford is that when one breaks down, you always know what the problem is.....

They circled it and highlighted it in blue, right there on the front of the truck!