I don't know about you guys, but all the Fords with modulars I've had, a '96 t-bird 4.6, a '97 cougar 4.6l, and my V10...

NONE of them have any pressure or vacuum when I open the gas cap.

Of course, they all have California emissions package too, being I'm in Metro NY.

 

well i have a 94 bird, 97 towncar, 00sd, 06fusion,and just sold my 04f150 and they all have vacume esp. in the summer. non california. i don't see how a pressurerized system couldn't be closed, you want air coming from your intake air, not your fuel feed, right?

 

I have no idea what you're saying in your last sentence...

My thought was that his fuel cap wasn't allowing air in to equalize the air pressure. You see, as the fuel leaves the tank something must take its place. That would be air. If the air cannot get in then there becomes a point when the fuel will not exit the tank very well. This is referred to as vacuum induced, fuel starvation.

Wooshing air entering the tank when you open the gas cap is a sure sign of this. However, air escaping is okay and can be caused by the heat from the vehicle or the ambient air temps.

I read the original poster's statement that the air was entering the tank when he took off the cap. Maybe I read it wrong.

BTW, don't ALL vehicles have to have evaporative emissions (gas vapors from the tank) equipment? Is it really just California? My 05 isn't a Cali model and I surely have a charcoal canister that traps those evaporative emissions in it.

 

AFAIK...there has been zero differences in the fuel system emissions requirements of California or any other state for over a decade now...ALL the fuel systems must comply with the Federal clean air and evaporative emissions laws... Calif and other green states are concerned with exhaust end of the game and thus some what different combustion timing and power robbing lean burn strategies, but not really that much different from the "tune" in the rest of the states... so lets stop confusing the issue with a bunch of Cali vs non cali crapola that is meaningless to the motor coach fuel system in question.....

From another post:

read up all about how it works here:

www.motorcraftservice.com/vdirs/retail/default.asp?pageid=diag_theory_retail&gutsid=diags heet&menuIndex1=17

You can read the theory of operation and OBDII tests and why for the entire evaporative system in a 05 or 06 non diesel around page 32 through 41 ..... interesting reading even for the non technically inclined


several things are not adding up and I suspect some bad info is clogging the thought process (colored crap is my rambling thoughts)

Vehicle sitting 80~90 days in humid area (less then full fuel??)

1/4 tank of gas left and it started hesitating real bad under acceleration (sounds like clogged fuel filter or weak pump to me)

Stopped went to top off the tank and there was so much pressure/suction on the gas cap it wasn't even funny (sounds like someone stuck on a NON venting cap to me)

Filled it back up and made it to Vicksburg,MS barely going 45mph

Advanced Auto Parts put a diagnostic tester on it and the thing read where two of the plugs were not firing

RV repair shop did another diagnostic test and determined that three plugs were misfiring

(OK now we got two different scans showing plug mis fires)

put in some stuff called c-foam or something like in the tank and said it was bad gas (sea- foam / c- foam who cares, more expensive snake oil... IMHO) (BTW some brands of gas will NOT sit 90 days and be any good--- some will)...BUt how the hell did plug mis fires lead them to bad gas????

made it about 100 miles to Birmingham and it started doing it again

did try loosening the cap and it did it after about 25 miles of driving

got the word that the tank was full of rust and needed to be replaced

(the curiosity here is plain old rust is easily kept out of the pump by the pickup screen...mud n dirt is another problem) An it's really too new a vehicle to have a lot of accumulated dusty dirty muddy sediment (OTOH-- it would explain a clogged fuel filter and fuel starvation induced power loss)

Now if we could just factor in those pesky scans with plug mis fires...hummm

 

lean missfire

 

what i'm saying is that if the fuel pump is sucking air through your gas cap to inject into the gas as it pumps why would you need an air intake? two completely different systems esp. when dealing w/fuel injection, just a thought anyway, i was just thinking that the fuel line should be full of gas not air? that is why they are pressurized, but after seeing some of the replys my thoughts are now that mabey some air does need to get into the tank, i can buy into the equalized theory, but a bad cap can cause all kind of running issues been there, bought the front row seat!!!

 

Just because there is air in the tank it can't get into the line unless the tank is empty. Fuel is pulled from the bottom and the air is on top. Like sucking a drink through a straw.

 

ok now take a cup that's 1/3 of the way full and spin it (like driving over a rough road) and you will also suck air w/your drink? what's all this mean i don't know, i was just inputing that all my cars have pressure built up when i releash the cap,,,, and back to the emmisions thing i don't think it allows for fumes to exit, that is why you have a return and a charcoal canaister, so you diffentely don't have air escaping? and the fed regulations didn't take affect on (8000 ?)and up gvw chassis untill somewhere around 2000 mabey later....cail. did have differnt laws....

 

WOW!!!
WHAT A THREAD. WHO HERE IS A CERTIFIED FORD MECHANIC?
NO ONE?????

WELL THEN I SUGGEST WE ALL PERHAPS TAKE WHAT THE ORIGNAL POSTER IS TOLD BY THE TECH AS THE TRUTH.

I HAVE TRIED TO PATENT THE "OVER THE PHONE MECHANIC" BUT THEY KEEP KICKING ME OUT OF THE OFFICE. huh???

ANYWAY..... I AM JUST TRYING TO SAY THAT MAYBE, JUST MAYBE WE DO NOT KNOW EVERYTHING ABOUT THE ENTIRE SITUATION AND AT THIS POINT THE SITUATION IS RESOLVED, SO LETS DROP IT AND SPEND MORE TIME THINKING ABOUT THE 2ND GUNMAN ON THE GRASSY KNOWL OR MAYBE KICKING THE DOG.ECT...

 

Are you saying (shouting?) that unless folks are certified Ford mechanics that they cannot participate in threads in which the author asks for help?

We most certainly DO NOT know the entire situation. I definitively agree with you there!

Kick the dog? Why you cruel $@%#

 

oK sorry if it came off like I was shouting. I use caps all day and did not ever notice it.

I am not saying that at all, It just seems like people get into arguments over little things and lack of knowledge. These people have been taken care of and are on their way, Why speculate what really went wrong now?

Kick the dog? Just to keep it in line and remind it who is MASTER

 

Well guys we are on our way finally! Ended up and replaced the tank,fuel pump,filter and sending unit. After talking with the Service Tech this morning apparently Ford has had several problems with this and decided to cover it under Factory Warranty! WooHoo!!!!! Saved us approximately $1800 but in the long run cost us a helluva lot more gray hairs than we had before. All in all I would like to sincerely thank everyone who put in their opinions on what the problem could have been and helped us get through this. Too all the members on the FTE Site have a Safe & Happy 4th of July and safe travelings to all!

The Wilshires

 

Glad to hear the good news. Hope ya have no more problems and enjoy your trip.

 

well,was the tank plastic or steel????,did ford ever say what they thought caused the rust/clogging problem,they fixed the issue but what caused the issue.thank's ahead of time.

 

Yeah...my wife does the same thing to me...