Fuel vapor purge; what are you guys doing with it?

I was curious what you guys were doing with the fuel vapor purge system?

Are you guys leaving it in and adapting it to the throttle body / intake manifold or just deleting all of it?

I figure a vented gas cap will be needed also if i go the delete route.

I left mine in to avoid fuel smell in my attached garage. I left out the temp switch and metal regulator but hooked the plastic switch to the back of the ls1 intake manifold. I ran the outlet hose to my intake between the air filter and the MAF. This way the canister gets a little vacuum any the time the engine is running and air drawn through it gets metered. Been working great for a couple years now.

Rich

Rich, do you have any pictures of how you routed all of that?

Rich L. wrote:I left mine in to avoid fuel smell in my attached garage. I left out the temp switch and metal regulator but hooked the plastic switch to the back of the ls1 intake manifold. I ran the outlet hose to my intake between the air filter and the MAF. This way the canister gets a little vacuum any the time the engine is running and air drawn through it gets metered. Been working great for a couple years now.

Rich

i did the same on a customers car we built this spring . it works good

Oh! Pictures! Nothing really good, unfortunately, as the car is under a tarp in the yard while my Mom's car is under the knife. Here you can see the line coming forward to the intake, wrapped in heat sheathing.

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And here you can see the vacuum lines. The source is to the top at the back of the intake manifold. It splits toward the right through a check valve to the HVAC controls. And toward the bottom to the plastic diaphragm type vacuum switch at the EVAP system.

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Hope that helps,
Rich

Thanks for the info Rich, its much appreciated. Ill probably do the same as i would like to avoid the gas smell also.

Rich L. wrote: but hooked the plastic switch to the back of the ls1 intake manifold. I ran the outlet hose to my intake between the air filter and the MAF. This way the canister gets a little vacuum any the time the engine is running and air drawn through it gets metered.

Thanks, for posting the pictures. Is the plastic switch you speak of the blue and black valve in the second picture? Where did you get if from the Porsche or GM motor? Could the outlet hose connect to the brake booster port in the back of the intake manifold, capped in your picture, at the back of the manifold? Or, could it connect to one of the ports that are capped on the throttle body? Thanks, for any input. My garage smells like a gas can.

That looks like a vacuum check valve in the second picture. I'm using the GM vapor canister purge valve that mounts midway along the fuel rail and feeds back into the throttle body, along with the GM vapor canister vent solenoid that connects to the charcoal canister. I don't know if it works yet, haven't been able to work on the car in awhile, but it is the factor setup for my engine.

The lines broke on mine taking them off of the throttle body. I should have been more careful.

Right, the little black and blue guy is a check valve. It's a 944 part used to let vacuum through to the HVAC controls and keep it trapped when the engine is shut off. This lets the HVAC stuff work for a while even without the engine running.

The vacuum switch looks similar but it bigger, maybe 3x the size, and has 3 inputs. One is the vacuum signal, connected by the little black tubes, and the other two are the bigger ones that are the actual vapor lines. One comes from the t-fitting at the firewall, which splits to the tank and canister, the other goes forward to the connection at the air intake.

Rich

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Ah! A diagram!

So in this, I discarded #17 and #21. I kept #15, what I've been calling a vacuum switch. I hooked it's little input tube #19 into the back of the ls1 intake manifold. The bigger input is #14 and I left that as original connecting to the t-fitting #13 which goes to the tank and canister. The switch output #16 I ran to the air intake. I actually deleted the little hose #16 along with the regulator #17, using the longer hose #22 which doesn't really show in this diagram very well. But that hose connects where #16 does in this diagram and goes to my intake, as shown in my pictures above. It's the one with the heat shielding wrap on it.

Is the picture worth the thousand words?

Rich

That's worth a million! Thanks Rich, that's excellent, and way simpler that what I did,I may redo mine now.

That helps a lot, thanks. I will look in my box o junk to see if the parts are still in there.

Rich, thanks again for the info and diagram. Finally got around to hooking everything up on my car.

What are your guys thoughts on running line #16 from the evap to the port on the intake manifold (after throttle body). I would like to have run it pre-MAF, but with the way the intake on my car is setup that wont be possible without some big changes to how everything is hooked up. Im not sure how much air would be moving through it but should i be concerned about unmetered air?

Well that's where the Chevy EVAP connects but that's after a PCM controlled valve. Do you have the solenoid and programming in your computer? If so, you wouldn't need the vacuum switch. You could run a hose right from the t at the firewall to the solenoid.

But to your original question; I'm not sure. It would probably affect mixture to have the unmetered air and the computer would adjust fuel trim. But I don't know how much.

Rich

All of the LS1 based evap stuff was sent to the dump a few months ago. Im not sure if the PSI engine harness even has a connector for it (dont think it does).

What i may try is putting a T of sorts where the air temp sender plugs into the air filter. Then, run the sender on one side and the hose for the evap on the other.

Can you draw a pic of what you are talking about?

87-944S wrote:Can you draw a pic of what you are talking about?

x2 im looking for a good one also i have nothing hooked up you guys running cats( on the exhaust ) with ur Vents ?