I am planning a carb to TPI swap in my 85 Trans Am, using a complete setup from my 88 parts car. Thinking of using a 4th gen plastic fuel tank in place of the 88 tank as it is a bit rusty and would need refinishing. Been reading through all the threads here on TGO and looking for just a bit of clarification:

1) Would a tank from a V6 4th Gen work just as well as an LS1 tank? From my understanding, the only difference is the V6 tank does not have the built in fuel-pressure regulator. I am planning to use the factory fuel lines and the FPR on the fuel rail. In that situation, wouldn't the V6 tank suffice? They are occasionally in the local scrap yards - I've never seen a LS1 car in the yard.
2) EVAP - Leave it unhooked, but run the line up the the throttle body? No emissions in my area and would be nice to get the charcoal canister out of the engine bay.

Thanks for any guidance!

 

New 3rd gen tanks are really cheap. Way less than the value of your time to pull a 4th gen tank and deal with mounting the filler neck, etc.

GD

 

I haven't heard good things here about aftermarket tank fitment with the filler neck, plus I have an original 88 tank with the correct baffling that I would use it I stick with a 3rd gen tank. Considering the 4th gen for the built in charcoal canister more than anything else.

Option 2 is to get my tank professionally cleaned and move the charcoal canister somewhere out of sight.

 

I've personally used two of the Spectra style tanks and both fit perfectly. Mostly it's either shipping damage (which should be something taken up with the seller/shipper) or user error. My 86 has one and my 91 has one. Both have the filler neck perfectly centered and did not require any modifications.

Not worth cleaning them for the price of a new one. And not worth messing with the 4th gen tank IMO.... again cost vs. effort for what amounts to a fuel container. Cleaning the stock tank is also inadvisable because the "slosh" container inside them is plastic and usually garbage. The new tanks have an entirely metal slosh container welded into the tank. Much better design.

GD

 

One nice thing about the 4th gen tank is there is no fuel odor even without EVAP. That integrated charcoal canister is sweet.

 

What's the advantage of not running the factory EVAP system?

Even on the swap i did in my 2nd gen, I went through the trouble of adapting a 3rd gen EVAP system into an aftermarket EFI swap fuel tank. No fuel smell, no over/under pressure building up in the tank (even on blisteringly hot days), etc... with the correct EVAP system, the aftermarket tank runs like GM designed it that way.

Unless you consider it so unsightly to have in the engine compartment that its worth the hassle of adapting a 4th gen tank to get rid of it...

And then hopefully you get the lines hooked up correctly to make it work properly. Not to mention that its able to pass smog when the inspector opens the hood and notices that a primary piece of emissions equipment appears to be missing....

Also consider that the 4th gen canister may have electrical component to its operation like the solenoid on my 1992 canister i swapped in. The solenoid is controlled by the ECM (which i also have hooked up for proper operation). Your earlier ECM may not be set up for that.

 

Right up there is the removable filler neck so you can drop the tank without dropping the rear axle.