FASI/FASA does work on limo, but you need to titrate it very carefully, and not add too much fasa/fasi. Also, add it slowly, and wait a bit before adding more fasa/fasi. If you dump a bunch in at once, excess fumaric acid WILL crash out and leave you with a less pure end product.
The reason being, is excess fumaric acid is not soluble at ALL in the limonene. I've had excess fumaric acid crash out when doing fasa on limo with freebase dmt in it before.
I find its best to just salt via fasw (fumaric acid in water) on your limo, and let that evaporate. A seperatory funnel (best method), or a glass pipette/turkey baster works very well here when retrieving your fasw after shaking/swirling/mixing it with your limo pulls.
Then freebase your fumarates/excess fumaric acid with lime, or sodium carbonate, ala a paste dry tek.
Meaning mixing what you scraped up after salting your limo with the fasw and evaporating that water, with an equal amount by weight of lime/sodium carbonate.
Then add enough water to get a paste like consistency. Not too much water, but enough to hydrate it all the way. IE not runny, but not crumbly chunks either.
Let that dry FULLY, dont use heat, a fan in a cool dry area works good, and you could throw in some annhydrous epsom salts at the end (bake epsom salts in the oven @ 400f for 2hrs). This will remove all the moisture and give you a powder, or paste if there's a lot of freebase dmt in the mix, as its an oil at this point. Cant stress enough here that you want it fully dry.
Then pull from your dried paste/powder containing your freebase, with dry isopropyl alcohol, or dry acetone. You don't need much, iirc, freebase dmt is very soluble in dry acetone/dry isopropyl alcohol. The less solvent you use the better. I'd do at least 3 pulls though. 25ml per pull is all i needed for a few grams of freebase i converted to fumarates a while back.
Then add fasa/fasi to your acetone pulls. Since your using acetone or iso, which will dissolve excess fumaric acid instead of crashing it out like what happens with sometimes with limonene, you get no excess fumaric acid, just fumarate salts of the alkaloids.
At least thats the procedure i've settled at after lots of trial/error. IMHO, performing fasa/fasi on freebase in dry acetone/iso works much better than freebase in limonene, in terms of a more pure end product.
The key here though, is keeping your acetone/iso dry. The acetone/iso that has your freebase in it (your pulls off your dried paste), and your fasa/fasi you add to that to crystallize the fumarates out.
A little bit more work, but imho, its worth it, and if you do it right, you get VERY pure fumarates.
From there, its very easy to get freebase crystals, by re-basing your fumarates and freeze-x'ing with warm naptha, or preferably heptane. Just do the same thing you did before, mix with lime or sodium carbonate and water to get a paste. You don't have to dry it all the way, but the dryer it is, the more surface area for the heptane/naptha to pull the freebase out.
Hope this helps, pm/ask questions if you need clarification.
And BTW, Acetone actually is a better solvent here. Its less polar than isopropyl, so dmt salts are less soluble, practically insoluble in annhyrdous acetone. Iso is similar, but dmt fumarate salts are slightly soluble in dry isopropyl. More so in dry ethanol, then methanol.
Basically, if you want alkaloid salts to precipitate out of a solution, usually acetone is the one that they are least soluble in. Not all the time, in every case, but for dmt fumarate acetone/fasa is better than fasi in terms of being the least soluble.
