Carpokes Porsche Forum

I am considering deleting my EVAP system. I’m currently replacing some fuel components, getting ready for 944 fest, and thought it would be good to replace all the rubber lines for the evap system. But then i looked at the diagrams..
I know i’m capable of doing all of it but it makes me want to just get rid of all of it and have the gas tank vent into the air. I live in Tennessee so i’m not worried about evap/emissions rules. Aside from using a tip valve in case of a tip over to prevent fuel from spilling out of the vents, can i just cap all vacuum lines, and remove the old rubber evaporator lines, charcoal canister, etc. I noticed about three hoses around the filler neck area. two going into it and one near it. Will disconnecting and capping those be a problem if i only have vents at the gas tank itself? I don’t know their exact function, nor most of the other evap lines exact functions around the gas tank. Aside from losing a little fuel over time, are there any downsides? I’m just now entertaining the idea so i’m not set on doing it yet, just mainly looking for information. If i end up replacing all the evap system lines, are they all the same size? It’s a rubber hose with braided cloth exterior. Here are the diagrams i’ve looked at. Thanks

Bump

I'll give you another bump - Tom or someone here will have some ideas I imagine.

Check your PM.
I'd be disinclined to modify personally based on an exercise someone I know went through that was resolved by reinstating a stock evap system on another make car, but its your decision. Some systems are heavily integrated and without knowing exactly what each part does and how it interacts with other parts, it could cause additional issues.

It was done by the PO of my '90 without issue. The canister was removed and replaced with a small K&N filter.

This is something Ive also wanted to do to clean up the engine bay. After reading various forums from years past, it seems a lot of people delete and plug off everything, and then add a small filter right at 30/31 in the diagram. Don't really see it causing any issues as long as you plug any vacuum lines, etc.

So, when you delete this stuff what you get is evaporation of the gasoline you pay good money for, and a stinky ass car in your garage. I can see it for a race car to cut weight, but not a street car. Just my opinion.

944er wrote: Wed Jul 24, 2024 6:55 pm So, when you delete this stuff what you get is evaporation of the gasoline you pay good money for, and a stinky ass car in your garage. I can see it for a race car to cut weight, but not a street car. Just my opinion.

My system is deleted and have yet to notice any stinky garage i still have the hose connected to the tank and will probably route it either to the ITB vacuum or just went it outside . I have not yet had 80L in the fuel tank so we will see how bad it gets then

I removed mine and added a Holley rollover valve (...didn't search for "tip over valve", which brings out a whole bunch of other options I would've loved to see!). Everything except for hard lines #29 and #27 (and their joining flex line) is gone.

Likewise I've yet to notice a smell in...over a year now. Maybe just immediately after filling the tank? Probably obvious/a non-issue, but you probably don't want to leave E85 in there terribly long, if it's atmospherically vented.


Edit: I plugged the vacuum switch bung in the rear water neck with this: https://www.amazon.com/gp/product/B07MPFDCY1 (M10x1.0 mm). For a cleaner look you can pick up p/n 94410431704, but that seems to run >$100!

The smell comes when the gas tank gets warm enough for the gas to evaporate and push fumes out. This becomes very apparent in the desert. If you keep the "two way valve" in the rear, the vapor pressure must exceed 2 psi for fumes to come out, which might not happen in colder climates. If you simply vent the tank to atmospheric, you will notice it at lower temperatures.