I'm using 2 new aluminum fuel cells in an Erod LS3 6.2 swap.
I heard that I had to create an area (air/fuel bubble) at the top of one of the fuel cells in order for the emissions to get a reading of the fuel vapor...is this true?
Can anyone help me out?

 

Mostly they check for the purge function working, and lately they just check OBDII for codes, one of which is for EVAP function.

 

Thanks for the reply.
I am wondering how to hook up the emissions on the Erod so it will pass in California.
I'm trying to find out if the emissions needs to sample fuel vapor from the fuel cell?

 

What year car is it going into? Anything 1974 and earlier is not checked, regardless of engine.
I live in Cali too.

 

I don't think it's "sampling fuel vapor" -- it's checking for pressure in the tank to be sure the system is not venting to atmosphere. I think.... On my car, I had them delete those functions in the ECM as part of the "tune" for the swap. When I pull codes -- nothing about that shows up at all. And no check-engine-light.

 

No. What Michael said above is correct.

Andrew

 

That makes sense.
The vehicle is an 1986 and it has 2 long fuel filler necks that are mounted high in the body, with the fuels cell well below.
I was thinking of tying the fuel filler necks together with a hose, then teeing off of the hose to the emissions.
I under stand that I would also have to change the filler necks to the screw in type, and same with the fuel caps.
According to GM, because its an ERod LS3, the fuel system has be be ups=dated to a vehicle that is 2006 or newer.
If newer vehicle are not allowed to vent vapor into the atmosphere, then how does Ford get away with the cap less system?

 

Omissions....Anyone?

 

There is always a cap...or a flapper door that seals after being filled up..

 

Your vehicle, being a 1986, has a simple Evaporative emissions system in place. It basically draws the vapors stored in the charcoal canister into the intake to be burned via the purge valve. If the original system is there, I'd run the vapor hose (the line from the tank to the charcoal canister) to the top of the fuel cell. Put a loop or two in the line before it goes into the fuel cell to prevent liquid fuel getting into the charcoal canister. That's a death sentence to a charcoal canister. Your ECM is OBD1, so no worries as far as check engine light coming on. Evap isn't monitored till 1996 models.

 

The filler necks are so high in the body work that I'm not worried about fuel getting into the canister.
The original fuel system was a Bosch K-Jet, which was thrown to the curb, but it did have a check valve located in the upper section of the quarter panel.
Do I need to put a check valve back into the E-Rod system or is the idea to create as much of a fuel tank vacuum as possible?

 

You don't want vacuum being built up in the fuel tank.

 

Elaborating on Andrew�s response, doesn�t take much vacuum to collapse a fuel tank. And pressure creates a volatile situation. Be sure vacuum can�t be pulled and pressure can�t build. My swapper had Bosch injection too (early 80�s) - I left the oem tank venting set up in place up to the charcoal canister. Vented the canister into the air inlet piping upstream of the mass air sensor. All the tank monitoring/purge valve software was disabled in the tune. Year 5 of the beta test. Sadly, doubt this approach will appease the CA smog ***** if they�re thorough.