Fuel Tank Venting
08-07-2011, 01:52 PM
#1
Fuel Tank Venting My fuel pump was getting really noisy a couple of months ago (96 Z-28), so I had it replaced. Since then, I noticed that when removing the gas cap to refuel, I no longer get the "whoosh" from the air entering the tank.
I looked underneath the car, and all of the lines appear to be hooked up, and I replaced the gas cap, to no avail. I disconnected the purge line at the engine, and sent compressed air back through the system (4-5 lbs. of pressure), and the only place the air was exiting, was the "non-connected to anything, vent line" at the EVAP cannister.
I don't get any codes, the car runs well, but I'm concerned that something isn't right, since there is a change in the car's behavior. Anybody have any ideas?
TIA!
I looked underneath the car, and all of the lines appear to be hooked up, and I replaced the gas cap, to no avail. I disconnected the purge line at the engine, and sent compressed air back through the system (4-5 lbs. of pressure), and the only place the air was exiting, was the "non-connected to anything, vent line" at the EVAP cannister.
I don't get any codes, the car runs well, but I'm concerned that something isn't right, since there is a change in the car's behavior. Anybody have any ideas?
TIA!
08-07-2011, 03:51 PM
#2
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So you're concerned about the "whoosh" going away? I'd say that noise when the gas caps opened is a bad thing seeing as that vent tube is supposed to keep pressure out of the tank itself? No noise when I go to fill the tank and take the gas cap off.
08-07-2011, 04:07 PM
#3
Joe, my concern is this...If I understand the evap emmisions system correctly, there's some minimal amount of engine vacuum in the system that draws the vapors from the tank, through the purge canister, and draws them into the engine, where they're burned.
When you shut off the engine, the residual vacuum holds the vapors in the canister. The "whoosh" you should hear is the release of this vacuum. Also, whenever I now shut down the car, I smell fuel vapors. I didn't before, and do now....
When you shut off the engine, the residual vacuum holds the vapors in the canister. The "whoosh" you should hear is the release of this vacuum. Also, whenever I now shut down the car, I smell fuel vapors. I didn't before, and do now....
08-07-2011, 04:41 PM
#4
Joe, my concern is this...If I understand the evap emmisions system correctly, there's some minimal amount of engine vacuum in the system that draws the vapors from the tank, through the purge canister, and draws them into the engine, where they're burned.
When you shut off the engine, the residual vacuum holds the vapors in the canister. The "whoosh" you should hear is the release of this vacuum. Also, whenever I now shut down the car, I smell fuel vapors. I didn't before, and do now....
When you shut off the engine, the residual vacuum holds the vapors in the canister. The "whoosh" you should hear is the release of this vacuum. Also, whenever I now shut down the car, I smell fuel vapors. I didn't before, and do now....
