Fuel system question - electical

[srubano@xxxx]

Ok, as of now I have been working on my fuel system and I am in the 
process of testing everything. Now my question is this... In the 
workshop manual D:04:14 it states that if a DWELL meter is connected 
to the Diagnostic plug pin that is connected to terminal 17 of the 
ECU module (which is the orange wire) I can measure the pulses cycle 
signal off of it for the Frequency valve. I am doing that I am 
setting my DWELL meter to a 6-cylinder setting and I am reading it 
off the scale (high end)! I hear my frequency valve going also. If I 
am correct in assuming that the pulse signal measured from this point 
should be approx 45 degrees than something is wrong with my system! 
Could it be I have a faulty O2 sensor? a Rich CO mixture? I placed a 
meter on the O2 sensor to measure the voltage (mV) and I get a 700mV 
reading....I know normal operation should be around 500mV. I guess 
this means that I have a Rich CO setting then? I tried to "lean" it 
out...but it doesn't affect anything electrically (Duty cycle or mV 
reading on the meter from the O2). Is it safe to say that it's a bad 
O2 sensor? One thing I have not checked (which is my next test) is 
taking readings off the O2 sensor when the engine is cold (just 
started).
I hope not since it's new. I am testing my CPR valve but so far it 
seems good (using a Bosch fuel pressure gauge). I have checked for 
vacuum leaks and I did not find any. I rechecked all of my vacuum 
hose connections and they are all going to the right places. The 
problem I am having is that the engine backfires in the exhaust when 
I rev the engine, that's why I am performing these tests. Timing is 
set at 13 degrees TDC, all new ignition components minus the coil. 
Fuel pressure measured from the center of the fuel distrib (where it 
goes to the CPR) 75lbs (5 Bar).