1993 240SX KA24DE guzzling gas. HELP!

[Mew2Senshi: The Driver]

So my dad's S13 with stock KA-DE is wasting gas like crazy, because it's running too rich. I checked for codes and it threw Knock sensor malfunction and Injector Leak codes. How can one fix this? It's his current daily driver. Thanks.

[mastadon]

Well that injector leak might be a clue. Not sure if serious though.

[Mew2Senshi: The Driver]

What could cause such injector leak, though?

[Mew2Senshi: The Driver]

OK, so my dad checked the spark plugs to see if a specific injector is the one that's leaking. No good; all of them were black from running too rich. Still no answer. Guys?

[silverarrow27]

Pop the fuel injectors off and look at the o-rings.