Changing FPR

[ducksplus]

How do i go about changing my fpr.. how do relieve the fuel pressure off the gas line so i can remove it without loosing gas everywhere..... The line is under pressure right/?? Where do i start?

mike

 

[ducksplus]

Does anyone know??

 

[410Fortune]

91 4.0L OHV.

There is a shrader valve on the fuel rail near the FPR.
You can relieve fuel pressure here, or you can do the old trick, pull the fuel pump fuse while the truck is running an let it die.

Replacing the FPR is pretty easy, 1 vaccum line, 1 bolt, 1 o ring. Make sure you put ATF, oil, or vaseline on the O ring before you torque the new one down or you will leak.

Good luck!

 

[ducksplus]

this shrader valve your talking about is the thing with the cap that looks like a tire valve? if so i have pushed it and nothing happens.. i had a 98 ranger and when i pushed it a little gas squirted out and you could tell it relieved pressure. does this not having pressure on it mean my fpr is bad?? why does it not squirt gas like my ranger did?
MIke

 

[410Fortune]

well yes this is the schrader valve for reliving/checking fuel pressure.

If you dont have any pressure in the line then either the truck has sat a while since it ran and the pressure has leaked out/back into the tank (normal, pressure is only held for a while after shutting down) or your fuel pump is not coming on pressurizing the system.

The fuel pressure regualtor does just that, it uses manifold vacuum to control the pressure in the fuel rail and injectors, The fuel pump puts out approx 80 psi and regulator at idle should hold the rail at 35-38 psi, anything over the 35-38 is retunred to the tank.

Maybe you should tell us what the problem you are having is?
What makes you suspect the FPR? The first thing to check is to verify the in tank pump is coming on.

 

[ducksplus]

Well i have had the diagnostic codes of
koeo 11 .. which is pass
cm... 41 which is lean on right side
koer 41 which is rich on right side.. which doesnt make since to me to be lean and rich but thats what im trying to figure out..
im getting 10 mpg which is not good... i have changed my maf and iac and o2 sensor... others seem to think it is my fpr or an injector problem.. the truck runs ok it just drinks alot of gas and smells like its really really rich.. and when i first got the truck before i changed the maf sensor every morning when i started it it would blow black suit out of the pipe and it would cover the ground black...so im just trying really to get my lost power and gas milage figured out.. the truck is in awesome shape and it is a one owner before me and i know the guy... it just has a drinkin problem???? do you think its the fpr??? or what is your imput...

thanks a bunch!!
mike

 

[410Fortune]

well instead of throwing parts at it I would check the fuel pressure at the rail, this will tell you if the FPR is okay or not.

I suspect leaking injectors, manifold vacuum leaks, etc.
A compression test, a feul system leak down test and pressure test would be good idea's and much cheaper then just buying more and more new parts.

It could be your 91 engine is just worn out.....

You get those codes after replacing the 02 sensor?
Being a 91 it should only have 1 02 sensor, and you listed the same code twice, 41.

 

[ducksplus]

no sorry the koer test was a 42 not 41... the cm was 41... that was before and after the o2 was replaced.. the motor has 180k on it.. it is all hwy miles.. its giving me a lean and a rich code on the same side... im going to replace the fpr then i guess ill have to take it somewhere to figure out if its just wore out or not...
the cel comes on about fifteen minutes after running then stays on unti motor is shut off.. then next time same thing happens...??? im really fustrated with it right now..

MIke

 

[410Fortune]

okay so it sounds like a code is popping up while its running, once its warmed up (into open loop mode) this is called a driveability code.

You only have a single 02 sensor so there is no "side" even though thats what the code defenition is.

Can you pull the code from memory after you shut the truck off?

 

[ducksplus]

after i shut off the truck and do the koeo test i get first the code of 11... whish i know is pass... it does the pause thing then gives the cm code of 41 which is lean... thats where it confuses me.. and i have done this test a few differnt times and its always the same.. ive reset the computer and drove then done the test and still the same???
mike

 

[410Fortune]

Could be the PCM itself. Are you sure the first two beeps or blinks are not for the V6 code?


Do you have anyone with a 91-92 Ranger or Explorer 4.0L with the same trans as you? If you do you might try swapping the PCM real quick and see what happens. I have seen 4-5 to date computers (PCM) completely fail.

 

[ducksplus]

im positive im reading the codes right.. so you think maybe its the computer??

 

[410Fortune]

I have seen it before, throw false or no codes, cause driveability issues.
HOWEVER since you are getting a code, that is the first place to start.
Sometimes replacing the sensor is not enough, because it could very well be the wiring to the sensor ( I am talking 02 here)

I would also like to see you check the pulse and amount of exhaust flow you are getting, power loss/poo running can also be a cogged/ing cat.

The 91-92 models are tricky, they have EGR, a MAP or BAP (same), and a single 02 sensor)

Now you did not say what exactly it is doing, if you just have a strong smell of gas it may be as simple as a bad canister purge solenoid.

Can you tell me what happens when the CEL comes on? Does it run rough? Loss of power? what?

 

[ducksplus]

When i start my truck it usually takes about 5 or 6 seconds to start.. then the idle goes up and down a little.. not bad but a little.. then i got to drive and it has a little hesitation, I replaced the maf, but after i get it warm it doesnt hesitate as bad.. when im driving it feels like the power is not like it should be.. and when the cel comes on i cant tell any difference.. im getting 210 miles to my 19 gal tank. but driving it seems to drive ok.. it just smells really rich and drinks gas with some performance issues like the hesitation..thats about how it runs..
Mike

 

[410Fortune]

CHECK THE TORQUE ON THE UPPER INTAKE MANIFOLD BOLTS

classic sypmtoms of a vacuum leak at the manifold.
Do a search for more on this.

Also have you checked all your vacuum lines? checked manifold vacuum or checked for leaks?

 

[ducksplus]

ive traced the vacuum lines i see and can find?? what kind of leaks are you talking about???

 

[410Fortune]

I am talking about any sort of broken plastic vacuum line to look for, you can check for them with the old spray around while the engine is running.

But also these early OHV 4.0L's are notorious for having the upper intake plenum come loose, causing leaks in the manifold, you will lose manifold vacuum and cause all sorts of issues. In extreme cases coolant can get in the combustion chamber, etc.

If you check the 10mm bolts you might find many of them are finger tight = sometimes sngging them up (careful steel bolt in aluminum) can buy you time, but the best fix would be to replace upper and lower intake gaskets (easy to do and not to expensive) Every OHV 4.0L I have owned has had 150-250K miles on it and needed the top end re-sealed.

 

[ducksplus]

ok so your saying i can spray a little soap and water to check any leaks around lines and such.... and just check the upper manifold bolts ?? i guess i can spray about any where to see if anything is leaking??

 

[410Fortune]

both. Two seperate issues.
Check the torque on the bolts, and also check for vacuum leaks at the vacuum lines.
I personally HATE the plastic ford vacuum lines, they get hot, old, brittle and well they just plain suck. You wont find any of those on my truck, I use good old fashioned rubber vacuum hose instead.

 

[ducksplus]

alright ill check all this when i get home this afternoon.. I really appreachate you trying to help me out!! ill post later tonight on this thread what i come up with.. Thanks again...