Fuel system screwing up

[N-Smooth]

So my 93 xj 4.0 decided that building up pressure in the gas tank and a screaming fuel pump is cool. It will seriously hiss for ten minutes when I crack the gas cap to fill it up and if I take the cap all the way off the fuel will shoot out several feet... Yeah it's awesome. Anyone have an idea?

I dented the tank pretty bad but that was several months ago and it just started doing it. Also I replace the pump, strainer and filter like a year ago.

 

[BEACH]

Thats awesome. Sorry wish I knew the answer. If you wanna bring it down to my shop I can have one of my guys take a look at it for ya.

 

[skippy]

You probably just have a plugged breather.....Does it still run good???

 

[jmaxj]

my XJ did that and i just swapped to a new cap and blew out the breather hoses and it hasn't done it since.

 

[N-Smooth]

it runs fine actually. it has to be a plugged up something, not sure if it's a breather or if the charcoal canister is screwed up or what. i crawled under there and couldn't see any damaged lines or anything :-\

 

[N-Smooth]

my XJ did that and i just swapped to a new cap and blew out the breather hoses and it hasn't done it since.

i was wondering if the cap could be part of the problem, they are supposed to release pressure at some point, correct?

good call on blowing out the breathers, it would be real easy to hook up the compressor and give it a go. are there two breathers on the top of the tank and one by the pump? i can't remember but i guess i'll find out when i get under there anyways.

 

[MikeGyver]

The gas cap lets air in not out. You can't vent hydrocarbons to the atmosphere. As fuel is used a vented gas cap allows this space to be filled with air so the tank doesn't collapse.

Pressure should be relieved through the charcoal canister purge soleinoid (if XJ's have one) into the intake manifold. Check that route to see why pressure isn't venting properly.

 

[N-Smooth]

the tank has two rollover/vent valves on the top and they connect together and run all the way up to the charcoal canister which has vacuum from the airbox and the manifold. part of this system is screwed up, i just don't know where. the passenger side rollover/vent feels loose on top of the tank, i'm wondering if it was pushed up into the body when i smashed the tank. but if it was broken i don't know why pressure would build... :-\

a new tank is $140 from the zone but i can't find the rollover/vents on their site so i dunno what to do about that or where to get them

 

[utah340six]

just take it out and shoot it.
pull the vent lines apart and see witch way its pluged, tank or canister direction

 

[N-Smooth]

just take it out and shoot it.
pull the vent lines apart and see witch way its pluged, tank or canister direction

you saw the way i treated it at lil' moab so we can't be surprised by problems like this

i'm going to pull the lines and shoot some air up them and see what happens but i get the feeling that it's the valves or the canister that are causing the problem

 

[DaveB]

I have several charcoal cannisters if you need one. I would check the plastic vacuum lines that go to the cannister they are notorious for cracking and making leaks.