I have a 97 F150 4.6, automatic 2x4. The problem is excessive fuel tank pressure. It set a code that it "can't release fuel tank pressure" and there is a LOT of pressure when I take the cap off. What could be the MOST LIKELY villian causing this irritating problem? Anyone have an idea?
Thanks, ss62

 

Does your truck have the factory gas cap?
Have you checked for knicks or blockage in the fuel vent hoses?

If yes to both then get it in the shop.

This code and fuel tank pressure monitoring was programmed into the ECM as a safety measure when the electronic tank pumps came out.

 

I have a similar problem. My Gas cap vents or burps out the
excess pressure. The first time it made this sound it made me jump!
I was standing close to the gas door. Now I don't tighten the
cap all the way anymore. Noone can give me a good answer as to where
the vent line goes and where it ends up on the engine. Is this
technology that necessary on vehicles? Early 150 caps are different
from the caps on 150's mad later in production year. Think my vent
line is clogged cuz a new cap made no diff.

 

>I have a similar problem. My Gas cap vents or burps out the
>excess pressure. The first time it made this sound it made
>me jump!
>I was standing close to the gas door. Now I don't tighten
>the
>cap all the way anymore. Noone can give me a good answer as
>to where
>the vent line goes and where it ends up on the engine. Is
>this
>technology that necessary on vehicles? Early 150 caps are
>different
>from the caps on 150's mad later in production year. Think
>my vent
>line is clogged cuz a new cap made no diff.
The guy I bought my F150 from last September said he had just put a new cap on it. Said it started making a noise like it had eaten a whole pot of northern beans and scared the heck out of him the first time it happened. It was excessive tank pressure blowing by the cap but the light wasn't on when I bought it nor did it come on until about 2 weeks ago. I fail to see why all this is needed on a vehicle but I suppose in the long run it helps make cleaner air for us all. But why all the valves and switches and more valves and more switches just to vent vapors back into the engine. Heck, run a plain simple rubber hose from the tank to the breather and be done with it!

 

>Does your truck have the factory gas cap?
>Have you checked for knicks or blockage in the fuel vent
>hoses?
>
>If yes to both then get it in the shop.
>
>This code and fuel tank pressure monitoring was programmed
>into the ECM as a safety measure when the electronic tank
>pumps came out.
Does the vent hose run to the charcoal canister or straight out of the tank to the motor? There's several hoses under there and none are labeled so which is which! I haven't been under it so I'll probably figure it out. But, a clue would be helpful beforehand if possible.

 

Bud, id deffiniutly get the truck to the shop! i recently had the bed of my 97 off and asked a guy about the 2 large boxes which are mounted atop the frame which are about 5x8 4" deep and he said they were filters which recirculate the gasses in your tank.he mentioned that he had seen some which plugg up on the return side and can put the tank under heavy psi and when you broke the seal with the gas cap you could even get doused with fuel if psi god high enough.good luck