There's also a reverb.
Ok, it's a well know fact that Jaco Pastorius used only Rotosound RS66LD round wound strings.
To get closer to the sound here, you'll need to double all you parts to get that chorusing effect (also used by Mick Karn, by the way), or try to approach it with a very slight delay.
Use only the bridge pickup (no neck pickup as he almost never used it) with tone completely rolled off (the capacitor was a 47 nF with a 250 kOhms pot). Play, as mentioned, over the bridge pickup with a heavy attack.
Boost the mids, but higher at 800 Hz. This is what makes a fretless sing.
And you'll need that Acoustic 360 kind of slightly to heavy distortion, so use this, with the mids all the way up, it's amazing how close you'll get : http://www.one-control.com/blue-360-bass-preamp.html
I owned a Fender Jaco Pastorius Relic Custom Shop bass with this preamp and the settings mentioned. The sound I got was really close to Jaco's sound (just adding a bit of 800 Hz to make the bass sing easily).
He was also using a bass cabinet with an 18 inches driver (Acoustic 361) that is also a great part of his sound.
Good luck in your tonal quest.