Danno74Z Posted December 19, 2011 Share Posted December 19, 2011 Hello, Working on my Z car conversion again and I have a couple of question on the EVAP system and the LS1. I'm in the process of installing a fuel tank and the tank has itself has a small vent by the sending unit and another larger one by the OUT and IN for the fuel pump. The original 74 OEM tank had hoses all over it like an octopus which all lead to the small expansion tank in the quarter panel. Also, the vent in the neck in the filler tube also has a hose going to the ET. It then appear (and correct me) that the vapors are drawn out of the ET to charcoal canister by vacuum via the intake manifold. Does this sound correct? What are you guys doing with the Datsun charcoal canister in the engine bay? Are you pulling a vacuum off the LS1 to get rid of the gas fumes and if you are does this effect the LS1 fuel mixture in any way? Thanks and all have a Merry Christmas Danno74Z Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted December 20, 2011 Share Posted December 20, 2011 I trashed all that stuff-I hope it works. We like global warming in Alabama and have no safety inspection or smog inspection. Smoke a doobie and you wont care either (that's a Colorado joke). Give me liberty or give me death! Quote Link to comment Share on other sites More sharing options...
zgeezer Posted December 20, 2011 Share Posted December 20, 2011 (edited) It is a good question for anyone who intends to build a California smog legal car. The JTR manual pretty much describes how the Datsun system works. My LM7 truck engine has what appears to be a computer controlled solenoid on the top of that tall intake manifold. It appears to control one plastic line that runs to the truck's evap canister. The second hand ebay special loom from some builder in Mena, Arkansas does not have a fitting for the solenoid; sooooo, I think mine must be deleted in the CPU. The idea of driving around with an open vent tube does not thrill me. I would like to hear from other LS1 swappers who retained the smog stuff. G Hello, Working on my Z car conversion again and I have a couple of question on the EVAP system and the LS1. I'm in the process of installing a fuel tank and the tank has itself has a small vent by the sending unit and another larger one by the OUT and IN for the fuel pump. The original 74 OEM tank had hoses all over it like an octopus which all lead to the small expansion tank in the quarter panel. Also, the vent in the neck in the filler tube also has a hose going to the ET. It then appear (and correct me) that the vapors are drawn out of the ET to charcoal canister by vacuum via the intake manifold. Does this sound correct? What are you guys doing with the Datsun charcoal canister in the engine bay? Are you pulling a vacuum off the LS1 to get rid of the gas fumes and if you are does this effect the LS1 fuel mixture in any way? Thanks and all have a Merry Christmas Danno74Z Edited December 20, 2011 by zgeezer Quote Link to comment Share on other sites More sharing options...
bjhines Posted December 20, 2011 Share Posted December 20, 2011 I don't know the LS1 ODBII system that well, but... I know that ODBII systems usually check the condition of the EVAP canister and that the tank is air tight. On startup, the computer will open and close a series of valves to draw a vacuum on the entire tank and evap system and hold it for a set time. Then the computer opens the evap purge line and then checks the O2 sensor readings for enrichment from the Evap canister's contents. If this system fails any of the tests twice in a row; a variety of codes are logged and a check-engine-light will activate. Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted December 20, 2011 Author Share Posted December 20, 2011 I don't know the LS1 ODBII system that well, but... I know that ODBII systems usually check the condition of the EVAP canister and that the tank is air tight. On startup, the computer will open and close a series of valves to draw a vacuum on the entire tank and evap system and hold it for a set time. Then the computer opens the evap purge line and then checks the O2 sensor readings for enrichment from the Evap canister's contents. If this system fails any of the tests twice in a row; a variety of codes are logged and a check-engine-light will activate. Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted December 20, 2011 Author Share Posted December 20, 2011 Hello, Way back when I had the tuner remove all the emission controls such as the rear O2 sensors and the evap stuff so to use the computer to purge the charcoal canister is probably not going to happen and I really don’t want to add it back. I guess I’m at a loss right now on what to do. I need a vent of some sort not build a vacuum in the tank nor do I want to smell gas fumes inside the car. Probably add a roll over vent valve to the small vent on the tank but what about the vent where the fuel pump drops into the tank and the one in the filler neck. If others could help out on what they did I would appreciate it. Dan Quote Link to comment Share on other sites More sharing options...
Aero Z Posted December 21, 2011 Share Posted December 21, 2011 What fuel tank (from what model/year) and filler neck style are are you using? It sounds like you're at least using the z filler neck. A lot of people here use the LS1 plastic tank and that's what I'm using. I had trouble with the vapors coming out of the tank through the vent/evap line (which was just cut). I'm still tweeking it but I could smell the vapors the worst when I was filling it up and at a full tank so it seems it was venting out through that line. As you use fuel it also needs air to come into the tank which can happen thru the filler neck since the cap isn't sealed, if you're using the z filler neck/cap. I recently added a fuel breather to that vent line and that pretty much got rid of the smell. I have considered you could probably keep the Datsun expansion tank and reroute the new fuel tank vent line into that and then keep the routing from Datsun expansion tank to the datsun filler neck. I have the camaro filler neck which I put up into the plastic datsun neck that i cut off and basically just keep the flange. A solution will depend on the fuel tank you're using and the filler neck/cap. some related links: http://forums.hybridz.org/index.php/topic/44974-ls1-fuel-tank-filler-neck-in-stock-location/page__p__378593__hl__camaro__fromsearch__1#entry378593 ( I kinda copied this but kept the upper end of the Z filler neck and shoved the camaro neck up inside it so it looks just like the original and keeps the Z cap) ls1 plastic tank info: http://www.thirdgen.org/techboard/ltx-lsx/342745-ls1-fuel-tank-plastic.html Hello, Way back when I had the tuner remove all the emission controls such as the rear O2 sensors and the evap stuff so to use the computer to purge the charcoal canister is probably not going to happen and I really don’t want to add it back. I guess I’m at a loss right now on what to do. I need a vent of some sort not build a vacuum in the tank nor do I want to smell gas fumes inside the car. Probably add a roll over vent valve to the small vent on the tank but what about the vent where the fuel pump drops into the tank and the one in the filler neck. If others could help out on what they did I would appreciate it. Dan Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted December 21, 2011 Author Share Posted December 21, 2011 Aero Z - Thanks for the information and links on the EVAP system. I have a little twist to the tank I'm using and I will post some pictures when I know what I'm trying to do will work. If I use the existing expansion tank like you suggest how do I get the fumes out of it? Currently, those fumes get sucked up to the charcoal canister and get burned - correct? Dan Quote Link to comment Share on other sites More sharing options...
cheesepocket Posted December 27, 2011 Share Posted December 27, 2011 Danno, sent a PM also. I attached a PCV hose from the vent at the top of my tank to a modified fuel filter make for a small engine that I got at a swap meet. I cut the plastic filter in two, then stuffed it with activated charcoal from a pet store. Then I glued it all back together, and routed the outlet from that filter to the outside. While not ideal in the world of EPA, the car doesn't stall due to vacuum buildup, and it doesn't smell like gas fumes ever. Quote Link to comment Share on other sites More sharing options...
mpramsey Posted December 28, 2011 Share Posted December 28, 2011 Danno, sent a PM also. I attached a PCV hose from the vent at the top of my tank to a modified fuel filter make for a small engine that I got at a swap meet. I cut the plastic filter in two, then stuffed it with activated charcoal from a pet store. Then I glued it all back together, and routed the outlet from that filter to the outside. While not ideal in the world of EPA, the car doesn't stall due to vacuum buildup, and it doesn't smell like gas fumes ever. I rewired my 280Z LS1 Build with a complete (entire car, not just engine harness) 2002 TransAM wiring harness. I am using the 2002 TransAm Fuel tank too thus the TransAM wiring allowed for OEM functionality of the purge/vent system. I gutted all the original 280Z fuel vapor cannisters and just capped the filler neck vent line connection. No issues with any fuel vapor smell. Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted December 28, 2011 Author Share Posted December 28, 2011 Hey Guys (Cheesepocket, mpramsey) Thanks for the replies...Really appreciate it. Today, I spent the entire day working on the fuel system. A lot of dirt under there - WOW. Cut out the wheel well using a spot weld removal tool, cut and welded in a new floor and then trimmed up the area for the new tank. A lot of work! Cheesepocket - I like your idea with the filter and charcoal. I might have to try that. Danno74Z Quote Link to comment Share on other sites More sharing options...
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