I'm not familiar with the term TBI for Honda's but I assume that means Throttle Body Injection? On older Honda's I am familiar with the DPFI system (Dual Point Fuel Injection). I assume this is what you mean.
Let me ask you, what differences did you see in your Fuel Economy? I know there's so many mixed feelings about it. MPFI has the potential to be more efficient if the maps are altered but the DPFI was designed for efficiency from the factory.
yes, I meant the dpfi system.
I did the swap a really long time ago. and back then I was really keeping track of my mileage. Its always been good even now with mpfi and a Ford Probe GT IHI RBH5 turbo. My dad used to drive it and claims the gas gauge would seem like it didn't even move..... I honestly don't remember.
I do love the VJ11 on those GT's. Fun cars. Parents had the Mazda 626 GT (same thing, 4 doors), and I don't think we got more than 340 or so miles from its 12 gallons. Fuel gauge was slow to move too. I think it's just a "feature" of gas gauges, all my vehicles do it.
On the Evap system, my ol' protege plumbed the tank gases into the intake manifold through the charcoal canister with a check valve (active when running). For those who ran without the CC evap (reduced weight=2lbs) it made a marginal change in FE, within driving conditional error. It did make the car smell like gas if left unchecked; if closed off pressure builds creating issues with the FPR.
As you state with the water example, the system only works when the tank of fuel is heated to build pressure. In AK I found it only affected it when the temps were above 65-70F. So 9 months of the year it did next to nothing (save deal with changes from fuel levels).