Fixed a gas leak but have compression building

dodge
caravan
gas-tanks
gasoline

#1

in-laws had a gas leak and had had the gas pump in tank repaired an the tank back on

then they began to leak as a drip

then it got worse

but only after the car had ran for a while

compression was evident upon removing the gas cap

i finally am in the area closing the three hundred plus mile gap only to see the van on car jacks

as it has been for two years

so in determining an assessment of the issue i drop the tank to find a line that led into the tank in front of the pump was diconected

seemed to be the source of the leak

put a hose clamp onit and reattached it and no more leak

however there still seems to be quite a deal of pressure beneath the gas cap when removed

it is a 93 chrysler 3.3 litre van

if that is any help

anybody know if this pressure is natural


#2

It is indeed normal to have a slight amount of pressure in a fuel tank…2-3 psi. Before pressure builds further, an automatic valve ovens and allows the vapor to bleed off into the “carbon canister” where the hydrocarbon vapors are captured and are purged into the engine when it is operating…If this system is not operating correctly, the “check engine” light usually comes on.


#3

i’m not getting a chk light
engine seems to be performing proper
is the carcan directly linked to the tank?
the line that was unhooked was in front of the modulator feeds in the tank
how do i begin to check the lines or the canister
is this something which is ecconical to replace?
is this something that can operate without by drilling a hole in the gas cap (wich has been suggested)


#4

I think he computer diagnostics in a 93 model pre-date OBDII, so it won’t catch a problem in the EVAP system.
I would leave it alone if there’s no check light, no leaking or smell of raw gas and no performance problems.
Likely normal pressure just pushed off the loose, unclamped hose.
Drilling a hole in the cap will disable the EVAP system, may cause the check light to come on, definitely release pollution, waste fuel and cause the remaining fuel in the tank to degrade over time.

p.s.: You’ll get more tank pressure in hot weather.