LS vapor purge

[socorob]

I would like to hook my purge valve up on my LS1 to my original Datsun vapor canister. I know the GM PCM looked at a lot of things to determine when to open it to purge the canister. I was thinking to do it in a sort of old school way, having the valve open up at startup for a set amount of time. I would just hook up a timed relay to open up for X amount of seconds on start. My questions I've been searching around here for the last hour or so are:

1. Is the solenoid 12 volts (I'm assuming it is).

2. How many seconds should it open when the engine starts, to purge the canister?

3. Is there another way that people usually hook these up?

 

I also asked this on LS1 tech.

[Michael Yount]

LS3 in my 1982 Volvo 242 -- FWIW, I just hooked the canister up to the inlet air piping through a barbed fitting -- placed in between the air filter and mass air sensor.  No gasoline fumes at all, tank vents as it should -- works just fine.  Left the purge valve completely off and capped the fittings.

[Richard Oben]

I have the Datsun vent system mostly capped.  Kept the vent at the filler and the one on the top of the tank.  The one on the top of the tank runs to the vapor tank on the Z and then the one from the tank runs through the Z vapor line to the front and goes in the air intake behind the MAF and ahead of the throttle body. I did not keep the purge solenoid either but I can only assume it would work.  My concern was without the vapor canister and its pressure sensor would it throw a code.  JMHO, Richard. 

[socorob]

I have the tank running to the vapor canister and that's it. I just want a way to purge the tank once in a while. On LS1tech, from what I can gather, GM didn't open the solenoid until the car was in closed loop, among some other factors we can't replicate on the Z easily. Apparently it would be bad (unmetered air) to run it through that valve right after startup or have it just sucking into that port at all times, as the car is still in open loop just after startup. It looks like you need to let the O2 sensors get hot to start working for the car to go into closed loop. At this point it looks like I will set the relay to wait 5 minutes after startup, then open a few seconds to purge the tank. Unless I find more information to the contrary, I'm still reading a lot on it.

[Richard Oben]

On the Z the vapor line runs into the Air Cleaner and PVC so not a lot of suction.  The LS runs the PVC to the manifold and gets air after the meter.  I am pretty sure any vapors will be minimal and should not cause any harm to start up.  JMHO, no real knowledge, just knowing assuming the computer runs rich at start up a little vapor is not going to be an issue.  Richard.