Excessive Fuel Tank PSI...
07-12-2011, 08:40 PM
#1
Excessive Fuel Tank PSI... Whenever I drive the car for awhile and go get gas; when i unscrew the gas cap alot of built pressure jets out. I know its pressure because the fumes burned my hand that had a bad cut on it. I thought tanks were supposed to have suction not pressure. Im running a fairly new stock gas cap too. Is it normal, or is it something i should concern myself about? Thanks
07-12-2011, 10:40 PM
#3
Actually, if you removed the EVAP system, pat yourself on the back for being a dumbass...
There is NO WAY to relieve pressure in the gas tank outside of the EVAP system. It is a requirement that only air can get IN to the tank via a one-way vent valve, but all vapors MUST go through the EVAP system to get burned.
I played that game too, about 11 years ago... Went through 6 SX Performance big-dog fuel pumps before I scorched my arm and almost blew up the car taking the gas cap off... There was some serious vapor pressure in the tank...
In all seriousness, I laugh when I see half of these retards talk about removing the EVAP system... It is there for a *REAL* purpose... People like to think they know better, but the only other way is to NOT have a sealed fuel system so vapor pressure can get out... Talk about a fire hazard...
There is NO WAY to relieve pressure in the gas tank outside of the EVAP system. It is a requirement that only air can get IN to the tank via a one-way vent valve, but all vapors MUST go through the EVAP system to get burned.
I played that game too, about 11 years ago... Went through 6 SX Performance big-dog fuel pumps before I scorched my arm and almost blew up the car taking the gas cap off... There was some serious vapor pressure in the tank...
In all seriousness, I laugh when I see half of these retards talk about removing the EVAP system... It is there for a *REAL* purpose... People like to think they know better, but the only other way is to NOT have a sealed fuel system so vapor pressure can get out... Talk about a fire hazard...
07-12-2011, 10:47 PM
#4
If you still have a functioning EVAP system, then checkout the main feedline running from the back up to the front. You will probably notice it is clogged with charcoal from the canister.
If so, replace the canister, then blow out the lines all the way up to the EVAP solenoid and replace the solenoid. I just did all the above on my '95 Z28 as part of it's rebuild.
If so, replace the canister, then blow out the lines all the way up to the EVAP solenoid and replace the solenoid. I just did all the above on my '95 Z28 as part of it's rebuild.
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07-13-2011, 09:34 PM
#8
Or, if you are talking about doing that in the engine compartment, you do know that before the charcoal canister there is a check-valve the only works if there is vacuum present... ie, if you don't have vacuum it will not relieve pressure out of the gas tank.
I have yet to hear a resonable excuse for removing the EVAP system outside of "because I want to".
07-13-2011, 11:40 PM
#9
And what, have gas fumes at the back of the car?
Or, if you are talking about doing that in the engine compartment, you do know that before the charcoal canister there is a check-valve the only works if there is vacuum present... ie, if you don't have vacuum it will not relieve pressure out of the gas tank.
I have yet to hear a resonable excuse for removing the EVAP system outside of "because I want to".
Or, if you are talking about doing that in the engine compartment, you do know that before the charcoal canister there is a check-valve the only works if there is vacuum present... ie, if you don't have vacuum it will not relieve pressure out of the gas tank.
I have yet to hear a resonable excuse for removing the EVAP system outside of "because I want to".
I do actually agree with you on this. If the system as designed is deleted, then something should replace it if you continue to run a pressurized system.
07-15-2011, 06:53 AM
#10
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when i got my car someone deleted the evap system and it built pressure , me being me i just went and got a small drill and drilled a hole in the cap so that the system can vent . i know it sounds ghetto and whatnot but unless your cornering very hard with a full tank , u aint gettin fuel that far up to lose any and its by far safer than a unvented tank
07-15-2011, 09:42 AM
#11
And what, have gas fumes at the back of the car?
Or, if you are talking about doing that in the engine compartment, you do know that before the charcoal canister there is a check-valve the only works if there is vacuum present... ie, if you don't have vacuum it will not relieve pressure out of the gas tank.
I have yet to hear a resonable excuse for removing the EVAP system outside of "because I want to".
Or, if you are talking about doing that in the engine compartment, you do know that before the charcoal canister there is a check-valve the only works if there is vacuum present... ie, if you don't have vacuum it will not relieve pressure out of the gas tank.
I have yet to hear a resonable excuse for removing the EVAP system outside of "because I want to".
07-15-2011, 09:50 AM
#12
FYI........the correct way to vent a tank is to run a line from the top of the tank over the height of the tank down out of the car and extend the tube below the tank............this way if the car flips over the fuel will stay in the tank............
07-15-2011, 10:39 AM
#13
Ok so heres a question. Could i just run a line from the charcoal filter, thatll hook up to the throttle body? or does that solenoid need to be operating it? (the one by the intake)
Or could the vacuum valve (thats inline after the charcoal filter) get deleted and have that line run into the CAI to get sucked into the engine? Just a thought i had.
Or could the vacuum valve (thats inline after the charcoal filter) get deleted and have that line run into the CAI to get sucked into the engine? Just a thought i had.
07-15-2011, 08:13 PM
#14
The vacuum valve you are referring to is there to only vent fumes when there is proper vacuum "seen" in the line going to the motor...
Theoretically you could remove the EVAP solenoid, but you run the risk of sucking in too much flammable gas vapor when you shouldn't... ie, it may backfire upon startup if there is sufficient pressure in the tank and if you have sufficient vacuum in the manifold, it will just dump gas vapor en-masse...
Besides that it would also be considered a vacuum leak at idle and such if it is not controlled with a solenoid valve. The charcoal canister does allow fresh air in if the system does not have pressure. That is why there is a fresh air inlet in the charcoal canister along with the tank connection and the "purge" (ie, EVAP line) port.
So, ultimately, with the LT1 PCM, again, you really don't want to mess with the system the way it was setup from the factory.
Theoretically you could remove the EVAP solenoid, but you run the risk of sucking in too much flammable gas vapor when you shouldn't... ie, it may backfire upon startup if there is sufficient pressure in the tank and if you have sufficient vacuum in the manifold, it will just dump gas vapor en-masse...
Besides that it would also be considered a vacuum leak at idle and such if it is not controlled with a solenoid valve. The charcoal canister does allow fresh air in if the system does not have pressure. That is why there is a fresh air inlet in the charcoal canister along with the tank connection and the "purge" (ie, EVAP line) port.
So, ultimately, with the LT1 PCM, again, you really don't want to mess with the system the way it was setup from the factory.
