Code 45 running rich

[Smuv_Gentleman]

U know ive been getting simular settings, except i have a code 45 with my 92 4.3 CPI. Ive changed my CPI unit, nut kit, pcv valve, and all but I cant find if there is a vaccum leak thats messed up or not.
The funny thing is that my fuel pump went out about 2 weeks ago and directly after I changed it, it hesitated, threw a 45code on me and drinks gas like Michael J on Powera!d. Do u know can U help me out?

[1993blazerlt]

you might want to check out your o2 sensor, when i got that code it was the 02 sensors fault

[Smuv_Gentleman]

Im not fully understanding O2 sensors. will a faulty one make you gas consumption drop from 20mpg to 13mpg?

will try, but also, I did see thta the T-shaped vac stem was broken in the back to the plenum and i've replaced it. I also found another that goes to the charc cannister in the front.

[1993blazerlt]

the o2 sensor tells the computer how much o2 is in the exaust, it then uses that info to adjust the fuel calbrations. It directly affects your fuel milage

[Sparky2263]

Keep in mind, if your mileage dropped and you're getting a code 45, your O2 sensor is doing it's job.

It's saying "Hey, I'm rich all the time and need leaning out!".

Problem is, you covered all the parts bases, CPI unit and nut kit, so what's needed now is some diagnosis. First, ensure timing is set properly. Second, ck. fuel pressure.

[1993blazerlt]

Keep in mind, if your mileage dropped and you're getting a code 45, your O2 sensor is doing it's job.

It's saying "Hey, I'm rich all the time and need leaning out!".

Problem is, you covered all the parts bases, CPI unit and nut kit, so what's needed now is some diagnosis. First, ensure timing is set properly. Second, ck. fuel pressure.

when my 02 went out it started to throw a code 45, if the sensor is starting to go bad it could be producing abnormal voltages causing the computer to add more and more fuel

[Sparky2263]

That is true. But an O2 sensor alone generally will not result in such a large drop in mileage (20 down to 13).

An easy ck. is to pop the brake booster hose loose while monitoring O2 voltages to ensure a rapid (less than .5 sec.) drop to under 100 mV.

All I'm recommending is some diagnosis before spending more money on parts. I have found my customers here would rather pay diagnosis time than parts charges. I also encourage guys who are going to try diagnosing their own vehicles to invest in the tools needed. DVOM, fuel pressure tester, timing light, vacuum gauge, compression gauge, basic scanner, 12V test lamp (nothing fancy needed there), all can be had for $200-300, possibly cheaper. After 2 or 3 repairs, sometimes 1, they've more than paid for themselves.

[Smuv_Gentleman]

..

[Smuv_Gentleman]

I got a good question. i havent checked my fuel pressure yet (my guage has been stolen) but I havent had all of these problems untill I changed my fuel pump, which is changed about once every 1.5 yrs. As soon as I changed it the last time, the hesitaions, rough idle, code 45, and gas consumption started. I wonder if the new fuel pump was bad to start or if the sending unit is bad. (the guys wants $60 for a diagnostic and Im trying to be a little frugal)

could there be a problem with the fuel pump system?
if there was something wrong with the return line of the fuel system and sending unit, would it back up the fuel thrusting more comsumptions and burning more than it should?

[1993blazerlt]

if you are getting more fuel pressure than you should be as in a bad regulator or clooged return line that could cause you to run rich

[Smuv_Gentleman]

ok, it couldnt be a bad regulator because i just changed the cpi unit

[1993blazerlt]

i see you have done the mojority of the sensor test and such, by chance have you checked the compression, spark plugs, wires, cap rotor, cylinder leak down. are you blowing any smoke throught the tail pipe? if so what color

[1993blazerlt]

is your engine running at normal tempature? Hows your oil pressure?

[Smuv_Gentleman]

Ive noticed that the oil pressure gauge isnst as high as it use to be before the fuel pump went out. It had a small leak and a bit of and oil leakage protectant fixed the leak. But the tempature and if fine. I've changed the spark plugs a few months ago and I wouldnt think that thats the problem. I also change the whole distributer and cap.
The smoke is kinda gray but it does have black powder/residues coming from it. Not sure about the compression test and cyl leak down.

[1993blazerlt]

how about the plug wires? Have you checked to see if any are burned? You might want to do a cylinder balance test also to see if there is a dead cylinder for some reason

[Smuv_Gentleman]

ok, i will change the wires and do a cyl check.

[Sparky2263]

i havent checked my fuel pressure yet (my guage has been stolen) but I havent had all of these problems untill I changed my fuel pump.................could there be a problem with the fuel pump system?


Anybody mention a fuel pressure test...................

[Smuv_Gentleman]

Everything worked out... I found out that it was actually a twisted metal line just outside of the sending unit. it was was the return line wich kept most of the gas pushed back into the CPI unit and intake causing excess gas to be pushed through the system and out of the exaust.
Thanks sparky and 1993Blazerit

[Sparky2263]

a twisted metal line just outside of the sending unit.

That would certainly jack the fuel pressure sky-high. Good to hear you got it fixed.