Honda Repair: my 91 civic, fuse box, pump fuel

Question
QUESTION: i have a 91 civic hatchback and my ECU code are 4, 8, and 16. i know i have to replace my efi relay because I've changed everything else in the fuel system but, how do i fix the problem with codes 4 and 8?

ANSWER: Could you be specific as far as what was replaced on the vehicle?

---------- FOLLOW-UP ----------

QUESTION: well i replaced the fuel pump, fuel filter, both injectors , all the fuel lines, and pressure regulator. But the main question is what do codes 4 and 8 mean and how do i fix it.

Answer
Code 4: Problem in the Crank circuit of the TDC/CRANK/CYL sensor.
Code 8: Problem in the TDC circuit of the TDC/CRANK/CYL sensor.

Both sensor are in the distributor & are known problems.
Replacing the distributor assembly with a "NEW" one will take care of the codes. You also need to reset ECU by pulling the Hazard fuse in the main fuse box for at least 10 seconds.

Also on the code 16, I think you mat have a code 15 which is a problem in the ignition output signal, which is also part of the ditributor.