Campeck

well. I drive everyday with it plugged off and nothing happens and i still pass emissions. so you dont HAVE to do any of this...

FRporscheman

Seems like there are varying experiences on this one. It's too bad we can't all just try it for ourselves, since there's the potential for damage or injury...

In this case, I'd focus my weight-reducing efforts on other things and maybe come back to this one later.

cjeckert

I just know that with the heat in VA i would not want my tank completly sealed...That just scares me to have that much pressure on a 19yo tank.

Campeck

varying experiences...
whos car has blown up. thats your fear isnt it? well it hasnt happened. DO ITTT!!!!

cjeckert

Yet how many people have you seen with engine fires due to burst fuel hoses. You raise the pressure in the tank the presure in the lines increases too.

Campeck

if the hoses have been changed and your fuel system is in proper condition it wont happen...

Little Porsche Boy

Anything can be done. Done right is another story.

The charcoal cannister system is an emissions control device. It's there to vent the gas tank and trap the evaporated fuel and suck it back in during the combustion process. So, w/o it the fuel tank needs to be vented otherwise. In pre-70's cars the tank was vented through the gas cap. But, now we have sealing gas caps so that the fumes can be recovererd. That's why the the gas cap is now tested during smog checks in many states. Some estimates claim as much as 20% of the amospheric hydrocarbons are from evaporated gasoline.

So, if the gas tank is vented properly, the charcoal cannister can be deleted. Whether or not it will pass smog is another story.

If you care about the environment, fix it. Better yet, ride your bike.

If not, take it off and vent the gas tank another way.

aribop

1. The gas caps are vented.
2. There is more venting going on situated in the car body right above the gas cap. Pull up PET and look at all the crap that is stuffed in that space. You've got a couple of hoses going into a plastic expansion tank of sorts called a reservoir.
3. The Euro car came with no charcoal canister at all. The line at the tank that would normally go to the canister is plugged.
The charcoal canister vents to atmosphere after it filters the gas fumes.

Campeck

um.. as far as Im concerned. there is ONE line going into the canister from the gas tank, and ONE line coming out that vents to atmosphere. nowhere on the can or anywhere is there a place for recondensed gasoline to go back into the engine...

am I missing something?
someone who actually knows for SURE on a 944 and has seen the routing please answer.

schwank

Routing is on page 175 of the shop manual volume 1. Doesn't really detail HOW it works but the expansion tank is actually attached to the fuel tank to catch liquid before it leaves the rear area. Vapor only should be trapped by the carbon filter. If you get liquid there, you have big problems. I believed that vaccuum caused the system to close once the car is running, venting the vapor back into the engine. The canister should only be in use when no vaccuum is present, ie, when the car is turned off.

In my experience in Oregon I have never had a visual inspection of the gas cap or any other emissions device, including on my 87 Scirocco. They just put it on the dyno and if your numbers are ok, you get the pass.

But hey, glad I started this topic! Lots of funky info here... at the moment I am certainly leaning towards pulling it and not replacing... remember I have to buy a NEW one to replace since I broke the existing old one. Keep it coming, lots to learn!

Geo

My money is with aribop and Campeck. Besides, I already know it's not going back into my car.

FRporscheman

If I had an extra 944 sitting around, and were invincible, I'd "DO ITTT!!!!". Yes, it's my fear, but we were given fear for a reason.

I heard that stuff about condensed fuel being reused on some other thread, it might be bogus. I would still vent the tank somehow, though.