jwbbuck

Do I need to run my vent to a purge solenoid and maintain some pressure in the tank to keep the ECM happy? There are only 4 wires coming out of teh factory fuel pickup assembly that I am using (from 2002 F-body) and I'm using an ECM from the same vehicle. I think the wires are: fuel pump power, 2 for fuel level and a ground, so I'm planning on running the vent line to atmosphere.

bczee

iTrader: (12)

What car do you have or putting theLS1 into?

oange ss

iTrader: (50)

you'll either need to run factory tank vent/evap system or vent the tank to atmosphere and delete the codes

95GreenZ28

iTrader: (70)

So you can vent it somewhere else besides going into the EVAP line? Sorry to bust into your post but I have been wondering the same thing. Then just haves the codes deleted?

ghettocruiser

iTrader: (17)

Im trying to come up with a solution as well. When I swapped into my 87, I built in the 4th gen evap lines and parts and figured it would work. Well...it wont work without the fuel level wire going into the PCM...and the aftermarket gauges wont work unless you disconnect the fuel level wire to the PCM. So...after I confirm that the EVAP system doesnt work now, I need to figure out what I can remove.

A few threads on venting the tank, but nothing seems like solid solutions. Im about to redo my set up...and Ide like to leave the evap stuff out of the equation.

So...in a nut shell...Ill be watching this thread. haha.

Justin

oange ss

iTrader: (50)

before the advent of emissions, tanks were vented to the atmosphere thru a filter setup,the problem with that, besides the enviromenal concerns, is you're gonna smell gas all the time and could be dangerous....most vehicles in the 80's and into the 90's used a charcoal canister and purge valve controlled by a vacuum switch or even a thermoswitch, this would be better than the simple vent design, but would still not be monitored or controlled by the pcm which would require the deletion of all evap codes...

jwbbuck

I had Wait4Me Performance modify the ECM, but I'm not sure exactly what they did concerning Evap system. I've been running the tank vented to atmosphere since I put the car together and I'm already tired of smelling gas. I may try running a charcoal can and leave the purge solenoid fitting open. Does anyone make an aftermarket charcoal can?

oange ss

iTrader: (50)

could probably adapt any can from a junkyard vehicle to your project, just make sure it's not too old or too beat up, you cant leave the purge open, if the pcm commands a purge event you'll be sucking in air ......

RE AND CHERYL

iTrader: (31)

Wierd... I just finished my LS1 swap in my 94 Z28. I used the 94 LT1 fuel tank, and ran the vent line to the purge solinoid near the fuel rail. I removed the wires and the codes for the tank pressure sensor and vent valve in the back and the system works fine. Purge solinoid opens for a few seconds when the car first starts just like it's supposed to.

I would not vent the tank to the atmosphere if you can help it. The rate of fuel evaportaion will be higher in the summer and condensation will get into the tank easier during the winter.

Re'

jwbbuck

I don't have the purge solenoid and vapor pressure sensor controls in my ECM and I would prefer to not use the solenoid. I'm not sure how the EVAP system works on a non-computer vehicle. I assume the system purges only a low engine vacuum (WOT) and that the valve allows high tank pressure to bleed off when the fuel tank pressure gets high due to heat. I would not to avoid a potential vacuum leak and plumb the purge hose somewhere forward of the throttle body. Sound like a decent plan?

Rodder

iTrader: (2)

tanks were NOT just vented to atmosphere before EVAP systems. Pre-EVAP cars DO have a vent in the fuel cap, BUT it has a check valve in it so that air can come IN to the tank, but fuel vapors can't get OUT. This keeps your garage from blowing up, and causes the big WHOOSH you hear when you remove a properly-working fuel cap on an old car.

67pete

I've installed the cannister in mine with all of the controls except the tank pressure sensor. What I did there was to in stall 2 resistors in series(2.2k & 1k), the 2.2k is connected to C2-46 and the 1k end to ground and with the middle tap connected to C1-64 the PCM is happy.

Steve VanS

iTrader: (1)

Hi 67pete

We're almost done with our swap of an LS1&T56 into a 1985 BMW E30 see

http://youtube.com/watch?v=2DbI3m6vs4Q

for our video of engine stuffing. So now its on to the wiring integration. We plan on using the fuel sender from the '99 donor Camaro, but not the fuel tank pressure sensor. We will use the evap canister, but are not sure about the evap vent valve. We will have the purge valve on the engine operational. We are hooking up to the stock harness connectors C220 and C230 for functions not directly on the engine. Did you go directly to C1 and C2 with your resistors, or to C220 & C230? Got any tips?

67pete

I installed the evap vent tube back into the fill line on the high side, you probably could vent that out into the air...~
The resistors are in the harness near C1 & C2, as I'm slowly weeding out all of the wires I am not using.

fast98

iTrader: (16)

all you need to do is put a resistor inline to the pcm so that it thinks the fuel tank is half full and your evap systems will work. let me know what year harness and pcm your using and i can be of more assistance

ghettocruiser

iTrader: (17)

I was thinking about trying that... but wasnt sure if it would even work...or just fry my PCM.

My harness and PCM and motor and fuel tank are all from a 99 Z28.

ANY help you can give me on that would be great!

Justin

ragefear

iTrader: (1)

just jumping on the wagon here, gonna need this for my 280z swap

76LQ9TA

iTrader: (1)

You can also install a filter breather valve on a vent line from the tank. This will allow the tank to release pressure and prevent it from pulling too much vacuum. The valve will release under a certain vacuum or pressure. There is a filter on it to prevent contamination. This has been installed on my car for 6 months. I never have a fuel odor in my garage. This is the same valve that is listed in the tanksinc. install instructions. It is a gm part used on the side tanks for large trucks. 10033125 It's around $22.

BLWN1

iTrader: (6)

Hmm this is interesting and nice to know.. Iworking out fuel system now..

KC Henry

I have a plug on the end of my Purge Valve that's just above the Drivers Front Coil Pack, and I have noticed that there is a LAAAARGE amount of air comes rushing out of the gas tank when I remove the cap to put gas in.

It almost seems like its building LARGE amounts of UNSAFE Pressure in my old 1978 Caprice Fuel system, is this ok or hard on the Fuel system at all toe be Pressurize with such great amounts of Pressure ?

Should I remove the plug from the Purge Valve and will it help relieve some of the undue stress/pressure that is getting put on my 29 year old Fuel system ?

I have a 1978 Caprice 2 door coupe with a 98 LS1 Swap btw.