i just finished swapping an ls into my 90 crx w/ a pr4
im getting code 43, "fuel supply system" and im wondering what could be setting this code.
the car still runs fine and code only comes on occaionaly

 

bump

 

Could be your fuel filter, or even your primary o2 sensor...

Search "fuel supply system"

 

im running obd0, how woul i test my o2 sensor and my fuel filter is new

 

9 chances out of 10 its the o2. The nonobd cars use a 1 wire o2 so if you use a voltmeter you can check the o2 sensor voltage. If you are uncomfortable with that grab another o2 and install it, clear the code and see if it returns after a few weeks of driving. hth