TXjeepTJ

iTrader: (8)

im getting ready to set up my system in order to get the gas fumes from the tank to my Throttle body. is the 'LS1 Evap canister purge solenoid' what i need to do this?

heres a pic of it, im geting ready to buy this- just making sure this is what i need


https://ls1tech.com/forums/attachmen...4&d=1209328788

G-Body

iTrader: (4)

Yep, you need that EVAP purge solenoid. I ran from the vent on my tank, to a charcoal canister, and from the charcoal canister to the solenoid

TXjeepTJ

iTrader: (8)

blah... i got the evap solenoid and just went outside to hook it up.. turns out i dont have the plug on the wiring harness to plug it in

soo i guess i cant run it that way? should i just connect a line straight from the vents on my tank to the throttle body?
i got my harness from efi connection, and its an engine harness only

hosspowerinc

iTrader: (22)

Why run it at all? Its just for emissions.

bczee

iTrader: (12)

On my Stock Chevelle Ssytem that I used, I just run a charcoal canister to the Fuel tank and as it is stock, then then pull some vacuum to the vacuum port on the can., for the vacuum, I used the LS1 port that is used for the EVAP solenoid. I have not had any indication of flumes so far, almost a year and a 1/2.

TXjeepTJ

iTrader: (8)

soo you just connected the throttle body port to the charcoal canister then to the tank- no solenoids or anythign electric? so the throttle body is constantly sucking in the fumes?

bczee

iTrader: (12)

Yup...

You can used the EVAP Solenoid, but I don't know if using the solenoid would do any good anyway, as it is controlled by the PCM and gets its input singal from the gas tank sensor, which I don't have.

G-Body

iTrader: (4)

I don`t have the fuel level or pressure sensor installed either, but it seems to work with the EVAP purge solenoid. I can watch the PCM open the EVAP purge solenoid (I watch for the command using HPTuners) So I don`t know for sure. I know that some have said you need the fuel level sensor, but mine seems to work without it. However I noticed that with HPTuners I can reset the input for the fuel sender......so I`m thinking of trying to reset it to work with my factory 0-90 ohm sender and seeing if it makes any difference....of course I haven`t found the time to do that yet.....but it would be a nice idea if I ever get around to it...

bczee

iTrader: (12)

G-Body (or anyone else) Is it the Fuel level sensor or the Fuel tank Pressure sensor that it gives the PCM it input signal from.. I thought it was the pressure sensor, but I could be wrong.

I am asking cause one of these days, I plan on swapping a Gen III/IV into something that will require all of the smog related equipement and this would give me some future info.

thanks..

ghettocruiser

iTrader: (17)

The EVAP system uses both tank pressure and fuel level to determine when it needs to purge the system.

My understanding was, that if either of those were missing, the system wouldnt function. When I had my system hooked up, I could smell the evap tubes and I couldnt detect any fuel vapor. Then, I hooked my fuel level up to the system, and after awhile, I could pull the hoses and smell fuel. That led me to believe that infact the system wasnt working without the fuel level.

The problem, as Ive said in a couple other threads, is that you can either have the gauge use the sender wire from the tank...or the PCM for the evap. You cant have both. The PCM sends a signal voltage down the sender wire to read the level, but the gauge does the same thing. I think.... I know the aftermarket gauges do...nto sure if you are using stock gauges.

So the two are fighting to see what the fuel level is. I think the gauge looses.... My autometer would just peg, and my EVAP seemed to work.

Its another one of those things that Im not srue what to do about. I have the 4th gen tank EVAP system set up. I havent decided if I want to fool with it, or just leave everything off the tank and let it vent (evap delete).

J.

bczee

iTrader: (12)

Ghetto.. thanks for clearing up some of the technical working of the EVAP.. We will all have research for a better solution..

Question.. how would someone with a 4th gen F-Body hookup a aftermarket gauge ?.. would hate to have to senders in a tank !... one for the PCM and one for after market gauge..!

ghettocruiser

iTrader: (17)

Thats the bummer... If you have a 4th gen F-body...You'd have to clip the purple sender wire before it goes into the PCM. Thats even per autometer's tech. Its the only way to run an aftermarket gauge. Its a flaw to the serial data set up in my opinion. There is probably a way to accomplish this. If there was a way to make a resistance reading deteriorate at the approximate rate that the fuel is leaving the tank. The pcm could use that and purge on a schedule rather than depending on the actual tank reading. But that sounds really complicated. haha.

Its not really a major issue for the 4th gen guys though. Couple reasons. One is there isnt a direct replacement gauge for the LS1 sender. The only one that works 100% is the $100 programmable gauge. In fact...the only way to get a gauge to even swing the right way is to send it back to autometer and have them reverse the air core. So that sort of deters some of them I think.

Another reason...is if someone with a 4th gen is replacing their cluster with autometers, something tells me there is more done to their car, and EVAP might not even be on their mind.

I just wish there was a way to confirm what the EVAP does wthout the fuel level signal. If it just stops working... Or if there was a way to trick it to work with HP tuners... something... Just not a whole lot of confirmed info.

J.

Novas Forever

I just wish there was a way to confirm what the EVAP does wthout the fuel level signal. If it just stops working... Or if there was a way to trick it to work with HP tuners... something... Just not a whole lot of confirmed info.

Ditto for me!

John Overton

the evap will work without the level working but it will not run the fuel system leak test, the pcm has to be able to verify that the fuel level is between 15% and 85%

ghettocruiser

iTrader: (17)

Can I ask where you got that info from??? Not that I dont believe ya. Just looking for some solid info other than the he said/she said.

Thanks!

J.

TXjeepTJ

iTrader: (8)

ok, im about to do an evap system w/out the purge solenoid.(thats a line coming from the tank-to charcoal canister to TB port). would this screw up something though? a constant suction from the TB straight to the gas tank just seems kind of sketchy, since its constantly sucking would that create a pressure problem in the tank?

also, real quick question- i googled this but just want to see what you guys say

setting up an evap system, does it improve gas mileage and make it drive better? i read that it improves your gasmileage and improves detonation giving you better power or something like that

loloone

iTrader: (4)

Great thread, I'm research into doin an LS1 swap in a Fox and wanted to CARB/BAR the car her in Calif. I know it'll be hard but if I can do it, I'd be golden!
Anyone else know? I also wonder if I can make the EVAP work with another tank? Hmm

TXjeepTJ

iTrader: (8)

i did some reading and testing and found out something pretty helpful

since my wiring harness did NOT come with a connector for my evap purge solenoid, i basicly thought i COULDNT use it.

this is what i found out:

the evap purge solenoid WILL STILL WORK without even being plugged in. on the gas tank side of the solenoid("can"side), it will hold a constant Hg(suction) of 6-7Hg. IF IT GOES ABOVE 7Hg, then the solenoid will AUTOMATICLY release the excess into the Throttle body.

i tested this w/ a lil hand pump suction deal i have. i put the suction on the "can" side of the solenoid which is the line coming from the tank. i pumped up to 15Hg and the solenoid immediately released the excess suction through the other end of the solenoid(going to the TB) it constantly released suction until it hit 6.5Hg where it then held it constant(plugging it up)

so this means you can use the solenoid as a way to regulate suction, if fumes in the tank exceed over 6.5Hg then it will release it into the TB. if its at 6.5Hg then the solenoid 'plugs' up the TB port so you dont have a constant suction on the tank(you would have a constant suction on the tank if you didnt use the solenoid)

hope this helps

bczee

iTrader: (12)

Good info..

Another question.. your finding are good or or for neg pressure in the tank (vaccum), what happens if there is positive pressure in the tank?

TXjeepTJ

iTrader: (8)

well there should never be a +pressure in the tank as long as your fuel pump is running. fuel pump=vacuum lol