this is a weird one...

[Wray-Wray]

this is going to be interesting to try to describe but here i go.....



ok i have 99 mountaineer 5.0 AWD

The motor has been leaning out at anything above 3600rpms
my fuel filter mite have 25-32k on it
i run injector cleaner threw it once a month like clock work
did Lucas tune up in a bottle like 2 k ago
plugs are 35k old
wires are 35k old
pcv valve is 1k old at most and boot around it is perfect
all the rubber lines are ok


I had codes PO171 and PO174 read on my computer
171 is bank 1 running lean
174 is bank 2 running lean

After cleaning my MAF sensor and that not getting rid of the problem(threw the same codes again a month later) and the aggravating hissing noise of a roasted vacuum line was apparently present

i went hunting for vac leaks and i found it, it was a rubber hose that went from a metal line the a believe goes into the lower intake manifold and runs down the side of the wheel well and goes to this round canister thingy(for lack of a better way to describe it sorry) under where the battery is

(also the vacuum line replacement didn't fix my problem....still leaning out but has not thrown any codes yet its been at least a week all hissing noise is gone now!)

if your laying under the truck with your feet towards the rear axle and the front driver side tire is touching the right side of you body fallow the wheel well till it stops it arc towards the front bumper and flattens out there will be a flap you can pull down reveling the canister thingy im talking about(its black, green, and white on my truck)

the vacuum line i replaced(as stated above) the line itself is attached to a fitting that looks a lot like the fittings for a fuel filter (black housing and the white locking clip) it all goes onto the green part of the canister it also has the same fuel filter like fitting where it hooked to the metal line coming from in-between my upper and lower intake manifolds


i had to replace my sway bar bushings in the front and noticed something very puzzling to me....BOTH of my axle seals wear leaking...not a big deal rite? wrong i just replaced them both at the begging of june.....so i said to myself....

those axel seals r brand new....now what could be making them leak....

installation error----not a chance i did it myself(and it sure isn't my first trip to the "ok cor-all" with axle seals)

pressure build up in the front diff and the pressure going out the weakest link because my vent tub is clogged---- very high chance


so i felt around for the vent tube and found it and when i traced it to where it stopped to replace it i found out it connects to that same canister thing that my vac line was hooked up to except the vent tube is connected to the white part of the canister thing along with i believe 3 other lines of which i have not traced to see where they come from yet


now if my vent tube is clogged then the canister thing isn't supplying what its suppost to....send threw the vac line...could that be leaning out my motor? and my axle seals have no connection the the motor leaning out....

or

if the canister thing is bad then its not relieving the pressure from my front diff making the axle seals leak.....and because my canister is bad its letting the vac line just suck in air leaning the motor out?


or do you guys think its something else and these two problems are not related?

and what the heck it that white green and black canister thing there called?



thanx very much in advance

 

[2000StreetRod]

fuel vapor management valve

The fuel vapor management valve is located under the battery tray. It is part of the evaporative emissions control (EVAP) system. The charcoal canister is located underneath the vehicle just aft of the fuel tank. According to my Haynes manual:

"On 1995 and later systems, fuel vapors are transferred from the fuel tank, throttle body and intake manifold to a canister where they are stored when the engine is not operating. When the engine is running, the fuel vapors are purged from the canister by a vapor management valve which is PCM controlled, and consumed in the normal combustion process. The fuel tank pressure sensor relays the inside fuel tank pressure to the PCM which in turn regulates the EVAP system purge control system. . . .

On 1995 and later models, poor idle, stalling and poor driveability can be caused by an inoperative vapor management valve, a damaged canister, split or cracked hoses or hoses connected to the wrong tubes."

If you hear air releasing when you open the fuel tank cap then you probably have excess pressure in the fuel tank and a defective EVAP system.

 

[Wray-Wray]

if its PCM controlled shouldn't it throw a trouble code itself? and its also hocked up to my front diff....idk if that makes any difference on what it is....

 

[2000StreetRod]

Isolate the lean codes

You are correct that there are diagnostic trouble codes associated with a defective EVAP system. If you think that the EVAP system may be the source of the lean codes (PO171 and PO174) then cap or plug the intake manifold vacuum line to the EVAP system, clear the DTCs and then see if they come back.

I believe the suggested fuel filter replacement interval is 30,000 miles. I suspect that premature fuel pump failure is due to clogged fuel filters. I suggest that you test the fuel pressure. If it is reads normal then replace the filter. If it reads low then replace the pump and the filter.

I don't know if a defective EVAP system can cause pressure build up in your front axle leading to axle seal leaks.

 

[Wray-Wray]

ok so im going start with the fuel filter replacement and checking fuel pressure do u know off hand what psi rage i should be in? if not i'll try searching

 

[ranger7ltr]

Ford fuel pressure specs...

For a 1999 Ford Explorer fuel pressure should be 65-72 psi... The pressure is higher with the returnless fuel system that you have and the fuel pressure should not vary at all...

For the pre 1999 Ford Explorers the fuel pressure specs are 30-45 psi... This is due to the fuel pressure regulator being vacuum modulated for system pressure changes due to change in vacuum...

 

[Wray-Wray]

ok cool thank you!

 

[Wray-Wray]

i unpluged and capped the vac line and sure enough my hesitation is gone!

im going to plug it back in before i leave for work in 30 min to make sure...if my hesitation comes back i'll know its the canister bought a fuel filter anyways so im going to replace it.... the dealer has it in stock for $42.13 so i'll pick one up tomm morning if thats the case then i'll swap it out and let u know thanks for the help so far guys!

 

[2000StreetRod]

inspect all lines & connections

I suggest that you inspect all of the lines and connections associated with the fuel vapor management valve before buying a new one.

 

[Wray-Wray]

i plan to do that at the point of install....if i have a roasted line i'll replace that first...then see what happens..buti want to have the parts ready if need b...i have a busy schedule and when i do find time to work on my cars its often spur of the moment

 

[Wray-Wray]

something else happend....i had my fuel vapor canister un plugged and my vac line plugged....my hesitation came back....my fuel pressure is 67psi at idol but drops below 65psi if i jump on the trottle....i have a brand new fuel filter on it i installed today.....i have a CEL code po455 "Evap Large leak" is what the code reader told me i had the fuel vapor canister unplugged to see if my lean code would com back and they didn't but the truck is still leaning out...any ideas guys?...im thinking i have a weak fuel pump or temp sensor is bad what do you guys think?



thanx in advance

 

[Scout3]

Wray-Wray,

I think your fuel pressure is fine. I fought my son's Taurus had 171 and 174 codes for a while. Turned out to be the EVAP system and lower intake gasket. Make sure you really have the EVAPS disconnected and all vacuum lines capped off. Did you clear that code and it came back after capping off the vacuum lines or was it stored in memory? The EVAP system must meet a bunch of requirements before the PCM tests it for operation and triggering a code. You could drive for months with it disabled before it finally throws a code. Also something as simple as a leaking gas cap or not having it on tight could cause the massive vacuum leak code.

Ed

 

[Wray-Wray]

there was nothing stored in the memory....when i unplugged my Fuel vapor canister...i cleared it because i wanted to see if my lean codes would come back and they didn't...within a week i got the po455 code what other parts of my EVAP sytem should i unplug and or cap off? i only unplugged the vac line to my canister and plugged them both...

 

[Scout3]

Wray-Wray,
I am not real familiar with the Explorer yet as I bought a 97 ex about two months ago. I am basing my replies on what happened to my other son's Ford Taurus. I believe the Evaps system should operate almost the same. I am not sure we are all talking about the same components. Others may may be able to clarify this better. You have a canister that is part of your vacuum system, that maintains vacuum when then engine is under a high load condition and does not produce enough vacuum. You also have a charcoal canister to recover gas fumes. You also have a VMV valve that could also look like a canister. I would start at the VMV and follow all lines to check for leaks. I am surprized that your code 455 came back so quickly. My son's Evap has been disabled for almost a year and it only trggered a code once. About ten conditions have to be met for the PCM to trigger the EVAPS to selftest. I think you are looking at the vacuum canister when you should be focusing more on the actual Evaps system. Good luck and keep us informed on how it goes.

Ed

 

[Wray-Wray]

What does VMV stand for so i can look it up in my haines manual...



figured it out sorry just got offa 12 hr **** and its a little after 2am here vapor management valve

 

[Scout3]

A 12 hour s..t, wow you'll need some vapor management after that.... LOL

 

[Wray-Wray]

lol u got that rite...

 

[Wray-Wray]

off on a tangent thinking about my truck could a cam positioning sensor be causing my hesitation problems as well? because of timing being off?

 

[Scout3]

Wray-Wray,
Pick one problem at a time. I would work on the 171 and 174 codes. They can be a little hard to track down. You still have a vacuum leak somewhere. If you have a scanner that measures short term trim levels it would make it a little easier.

Ed

 

[Wray-Wray]

are those the really expensive ones at autozone? and advanced?like $250+