GTA91

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I've seen some guys have these on their LS1 3rd gens and some don't. What should I do? It mounts in between the driver's side valve cover and the intake. It has a line that runs to the TB also, and then a fuel line coming out of it and a electrical connector. What are you guys doing? I removed my charcoal canister also. Can I run the line from the LS1 fuel vapor solenoid over to the hard metal line that used to connect up to the charcoal canister or what? Will this work? I'm kinda dumb with some of these systems on our cars. Thanks for any help, pictures greatly appreciated.


thanks!
-Jeremy

Ace

iTrader: (2)

yep.. it would go to the vent line on the tank.. it will just act like the charcol canistor instead of ventin it out there.. just pulls the vapors back into the engine with vaccuum..

i did it the hard way and used the return line and an ls1 tank

GTA91

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So that will work? Can anyone else confirm that?

Awesome!

Knyghtmare

The vapor solenoid on the LS1 engine works off of the pressure sensor in the 4th gen gas tank. The 3rd gen gas tank doesnt have this, so the LS1 PCM isnt getting a signal when to turn it on.

So in my opinion the best way to do this is to plug in the solenoid using the plug off the LS1 engine harness and use LS1 Edit to turn the solenoid on and keep it on at all times. Then you can just delete the 3rd gen charcoal canister and its wiring all together. Then delete the PVC charcoal canister hose and get a rubber one that you can run to the LS1 Solenoid.

If you dont and you hook up the solenoid and it doesnt turn on, the pressure in the tank has no where to go and it starts to blow by the fill cap and makes a loud whistling noise. It did on my car. I just loosened the gas cap a little till I could get hte solenoid turned on.

GTA91

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Thanks. I'll do it like that and tune it "on" all the time!

GTA91

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So you just hooked up your the hard metal line from the gas tank (over by the charcoal canister) to the solenoid thing on the intake and tuned it to be on all the time? I was going to do this but a friend said it might eventually suck gas all the way up to the motor and put extra gas in the motor there at the TB connection. Anyone???

Knyghtmare

Yeah pretty much, and I havent had a problem with it.
From the charcoal canister there is a small PVC hose and I took that all the way off and I put a rubber line from where that connecter to the selonoid. Its not directly from the hardline there is a soft line with a filter on it too. You shouldnt have a problem with it either. I dont think there is enough pressure from the tank or enough vaccum to suck any gas from the tank.

If you wanted you could just let it vent into the air too. Not very envoromentally friendly, but I dont think we are hippies here.

GTA91

iTrader: (1)

Just to make 110% sure... you have the hard metal line from the gas tank... it comes up the passenger frame rail and stops near the charcoal canister. Then you have the factory 3rd gen rubber hose with its little filter on it, and then a hose from that over to the 4th gen solenoid near the driver's valve cover. Then you just tuned it to be on all the time??

Thanks for the help!

Knyghtmare

Yeah. Here is a picture, look at the very bottom middle, it shows the filter thing I am talking ab out. After the metal line there is rubber hose then the plastic filter with its plastic fittings, then there was a PVC line running to the 3rd gen canister. I romoved the PVC line and added the rubber line shown and routed that to the solenoid.

GTA91

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Thanks! That's what I did last night. Hope it works out ok!

GTA91

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OLD post... but anyways... I did run my line like we discussed but we never "tuned" it on all the time. I've been driving it some (maybe 1000 miles on the swap) and haven't had any issues but I do need to turn it on. I've heard some 4th gen stories about the motor not running right with excessive fuel tank pressure (which I may have). Any thoughts on that???

MrDude_1

i BELIEVE by default, if it doesnt see the fuel pressure sensor and throws the code, it keeps the vent open.

id double check that on the hptuners forum, or LS1tech (or both)

GTA91

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That's cool... guess I can check it and see if its sucking or not

StevenK

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Pics!

Lol, everything you do I'm always asking for pics.

GTA91

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Pics of what? Just remove your charcoal canister and all that BS, then you should just have a hard metal line left sitting there. It is what runs back to the gas tank. Take a rubber hose and attach it to the hard metal line and then run it up to the LS1's fuel vapor solenoid. You're done! Now you just have to figure out if you have to tune it on all the time or if it will be on by default since there isn't a fuel tank pressure signal... that's what I'm trying to figure out yet...

0078red1

did you ever figure it out man

GTA91

iTrader: (1)

I'll have to look at it and see what's going on with that sensor and the PCM. I've been running it this way for years... can't remember if we just disabled the code and let it run all the time or what.

*The way I did it is definitely the easiest way to plumb it all up.

0078red1

Iv been doing the same for sometime I haven't hooked it up but when I got my harness worked for my swap the senoild was left on the harness. But good thing I haven't gotten a check engine light yet lol any help would be great thank you I love your swap man and read lots of stuff that helped me out