The Unlimited Jump Jet option only makes the jump jet fuel burn out faster than if it wasn't active, everything else seems to work fine, except for that, I have tried turning it on while in the main ship, cause I wasn't thinking at the time, then later after a restart only after getting off the ship and trying it then, both ways it burns through the jump jet fuel like crazy, I only get about 2 seconds worth of jump time.
Please do what CyPHeR said above your post.