The pressure of the fuel in the fuel rail should not have any bearing on the pressure created by the injector itself. Therefore atomization of the fuel will always occur. Unless of course the injector was starved for fuel...but then his mileage would be HIGHER since he is actually using LESS fuel. But the engine will run like crap.

 

monsta ,the injector doesn't create the pressure
the fuel pump does ,all the injector is ,is a solenoid valve that opens and closes on command pulse.

if the pressure is down in the fuel rail the atomization of fuel is not efficeint(still can't spell)
thus yes his vehicle runs like crap but also requires more fuel to get from point a to point b

I gotta be right Haroutd said I was worthy of wisdom!

We are all right I declare!
Now no buckshot please!
Rich

 

I stand corrected.

 

I must add to this discussion that the pressure in your fuel rail is contolled by a regulator. The regulator maintains the correst pressure at all times, most are vaccum controlled or you can buy an adjustable one but in either case with a clogged filter or no clogged filter pressure will be the same. If filter was clogged to point of lose of pressure then cylinders would start to go lean and computer would just increase pulse width of injectors to compensate. With a extreme pressure lose the O2 sensor would see a very lean condition and set off a code. my .02

 

I stand corrected also ,totally forgot about the fuel pressure regulator. but if the pcm increased the pulse width (means the injectors try to stay open milliseconds longer ) the use of fuel would be
increased correct?

We are all correct !!!!!!!!!!


Wait except monsta he can never be right !

sh sh shish ,I didn't say that yeti! did!


Rich

 

Unless its a Diesel... then Monsta could have been... gulp... right.

Matt

 

I don't want to start a battle here but, the computer will increase the pulse-width only to compensate for a lean condition or an increase of air being metered by the mass air sensor. If by some chance fuel pressure drops and O2 sensor see lean then pulse width increases to match same amount of fuel that would be used with correct fuel pressure. This happens to a certain point of correction. The computer and the O2s work to maintain a stoich condition which is approx 12.5:1 air fuel ratio. I still say that pressure will remain constant even with a dirty filter, a fuel pump is capable of supplying way over 100psi of pressure, normal psi for fuel rails is 42 for most fords and 60 for most chevys. In either case it would take a lot to lower the pressure in the rails. Also as I stated earlier the computer and O2 sensors always maintain the same stoich condition, unless you have custom programming or are at wide open throttle, or bad O2 sensors. Under normal driving the computer reads O2 sensors and is constantly changing pulse width.

 

BFT2002!,
your not starting a battle and don't feel that way!
I don't know everything ,thats why I came to this site. as you problably did ! Or maybe you do know everything! he! he !
these kinds of discussions keep my mind young!
he he .
I take it you are involved with fuel injection engineering or have some associated background on this subject !
I will study your info and see if I have an semi educated answer for you ! maybe!
but give me time !I 'm old mind doesn't work too fast anymore!
All your input is completely welcome here on any subject !

Stick around and we all will learn .

by the way
welcome to FTE if no one else has welcomed you !

Rich

 

Please reply to earlier post, it was the correct answer.
really guys if the filter effected gas milage i would just filter my gas before i put it in the truck and then remove the inline filter altogether for the biggest increase on mpg possible, and my gas milage would go from 8-9mpg, to maybe 30mpg??? (i dont think so) .... get my point
once again if your hoping a cleaner filter will increase milage, your just wrong.
Jetjock16.

 

Jetjock
your allowed to think what you do !
but to demand that you are correct means nothing
thats the kind of attitude not needed !

Now a discussion like the above post would have went further in this topic ,than what you have presented ! you have made good points also!

again we don't know all the info behind this gentlemens filter change do we! so how can one say it didn't efect his mileage.I certainly wouldn't

BFT2002 ,has given us much useful info ,I hope he stays around to enlighten us with his knowledge
of other subjects.

Just my $.02

Rich

 

well i don't own a superduty, but i did change the fuel filter on my 95 f150 3 weeks ago. i went from 8 mpg up to 11-12 mpg and that is all i changed. same gas station, same driving style, and same cold as ***** temperatures. my truck is running much better with more power now, and its not sucking fuel quite so bad, so my vote is.... yes it does give you better fuel mileage if its clogged and you replace it.

 

Forty, i understand your point, and i definatly dont want to come off as a rightouse jacka$$, as my post may make me out to be, there is just soo much good real info on this board that it twirks me wrong to argure about something like this that is just off, the dynamics of the argument crazy, i am a mechanic, i do understand how things work, and this is just like arguing that 1 plus 1 equals 3, it is just frustrating, i love to help people by posting the correct answers to questions/problems but i hate it when anyone offers the correct answer around here and everyone pipes in with their opinion on a matter that is factual.

ie

1+1=2 if you dont think so your wrong.
reply:


no, actually 1+1= 3 in my opinion cause of this

reply:
no 1+1=4 cause my friend did that

on and on and on

defiantly worth arguing about if it is a SUBJECTIVE topic, but in this case it is factual, the topic is OBJECTIVE and there is only one right answer, im sorry
i will not post on this topic anymore and i appoligize to anyone who thinks im being rude, im only frustrated at this topic, but willing to help any of you any time, so please post away
Jetjock16.

 

Guys, wow I had no idea this would be such a hot topic. I guess anything about saving $$ on gas is interesting!

Anyway, I still have the old filter and for the sake of investigation I would be willing to do one of a couple of things to help get more info for this.

1.) replace the old filter and run the test again. (would take 2 weeks to get results)
2.) test the current fuel pressure and then replace the old filter and test the fuel pressure.
-I just cked on the price of a guage its $40 so it would be better if someone in the austin, tx area who already has one could come out and help me with this one
3.) ship it to someone who wants to try this.
4.) Open to suggestions!

 

Well, lets see if I can add some gasoline to the fire!

OR

Here is what I think I know about this!

It is the VOLUME of gas that an engine needs to run properly.
That means not only pressure, but also rate of flow (GPH)!

Think of it as pressure and size of pipe (magical calculation) = GPH.

The new fuel filter does not increase MPG, but restores MPG by allowing the volume of gas to flow as was designed.

A clogged fuel filter will not reduce line pressure, but does reduce the rate of flow!

Therefore, the PCM (with O2 sensor reading) will increase the time that the injectors stay open.

But the injectors can only stay open for, or up to a certain length of time. This is due to the designed duty cycle of the injector.

Once that maximum time is reached and the engine still needs more gas, the engine will lose power.

Also, because the flow rate is less than required, the nozzle on the injector will not be able to properly atomize the fuel, leading to loss of power but still not create a "lean" condition (not 100% sure on the mechanics on this point).

Injector timeimg is related to cam timeing and phasing with crank.

BTW, (I might be wrong) the O2 sensor is really more like a switch, were it has only 3 settings, lean vs. correct vs. rich. As I understand it it is a relatively simple sensor.

OK!!! Abestos suit on, fire away!!!

HarryO

 

Harryo!
Come on in the water is warm!

Charles I got a better Idea just throw some dirt in your fuel tank !!!!!!!!he he he

Better yet Monsta will come over and drop some little turds in the tank ,that should increase your mileage! Rich