Please help guys, I'm at my wits end. I'll start at the beginning... I was on my way to work about 3 months ago, and it started acting like it was running out of gas (gauge said about 1/8 tank)and it cut off. I thought maybe the gauge had stuck and I was out of gas. I called a coworker and he brought me some gas. Car started after several minutes of trying but would barely idle and wouldn't take the gas at all. I thought maybe I'd sucked gas up in the fuel filter, so I replaced it. No luck. Since then I've replaced the plugs, wires, distributor cap, rotor button, I added a fuel pressure gauge on top of the fuel filter and it says my fuel pressure is exactly right. I replaced the coil and tps, and have checked every other sensor I could find by checking the resistence just like the manual says. Now the car will idle fine, but won't take the gas unless you go extremely slow. If you dump into it, it bogs down and will cut off if you hold the pedal down. If you let off, it will pick back up and idle, meanwhile it's puffing black smoke like a dadgum freight train. I've taken the plugs back out and they are completely black. I'll clean them and put them back and no change. I don't know where else to check, and my Z71 is eating me out of house and home since it has become my dd the last 3 months. It gets about 14 mpg instead of my Civic's 32 mpg. Any help will be greatly appreciated. Thanks!!!

 

Any cels?

 

sounds like its running way to rich with dirty injectors
put an injector cleaner through it

or it could be your O2 sensor as if its stuffed it will cause it to run rich

 

only 41, which if I'm not mistaken is O2 sensor. That's probably been there forever because I've had the car 3 years and the cat was gutted before I bought it. I live in SC and there are no emissions here, so I haven't worried about replacing it.

 

I also took the fuel rail off and the injectors out and cleaned them very carefully. Didn't have any way of checking the injectors, except putting a long screwdriver on them and checking to make sure they were all clicking with the car running. They were really, really dirty, though

 

And your wondering why your dumping black smoke. Are you sure that's the only code you have? And its fuel on your spark plugs and not oil right?

 

Yep, that's the only code. It would smoke a little before, if I got into it pretty hard, but never anything like this. I didn't change anything from the way it has been for 3 years now, except a really good tune-up. With the cat being gutted, I hadn't given much thought to the O2 sensor code, but is it possible that after several years of it being that way, that could be my problem all of a sudden?

 

I wouldn't doubt it. Does the smoke smell like fuel or oil? Is it black like you said or blue?

 

It smells like gas, like it's flooding. In the last 3 months it's been sitting in the yard and when I'd get an idea or ask someone something to check, I'd go start it up, and it's used over 1/4 of a tank of gas in that time. I've taken down my dirt road, less than a quarter mile 2 or 3 times and starting it in the yard.

 

Well you need to fix the o2 and get a cat..and Id run some injector cleaner through there, if not just get new injectors

 

Possibly the temp sensor also and if its dumping that much fuel you may want to make sure its not washing down the cylinder walls. Can eat up a set of bearings quick if you dont watch it.

 

I understand that to clear cels and make it exactly right, they need to be fixed. My question is why after several years would it be absolutely fine one minute and like it is now the next minute? It seemed to me like it would have been a gradual change if that was the problem. I've run injector cleaner through it as well.

 

IAT?

 

No, sorry I should have been more specific. The coolant temp sensor. Ive seen them go bad and make a vehicle flood like crazy. Should be two on urs one in the thermostat housing and one under the dizzy, if I remember right. The one in the thermostat housing should have two wires and runs to the computer. It adjust the fuel according to the engine temp (change this one if its bad). The one under the dizzy goes to the gauge in the instrument cluster.

 

Replaced coolant sensor in thermostat housing (old one broke while I was trying to take it out to test it) and it's still the same. Any other suggestions?

 

What is the fuel pressure at?
I had a similar problem, where the fuel regulator was not regulating, pump was delivering 100 PSI to the injectors,(with no return circuit) flooding engine, killing 02 sensor and the cat as well..fuel pump will sound loud, gas will leak past the rings into the oil, and raw gas will also be exhausted...

check to see if any fuel in the return line while engine is running..fuel pressure should be 40-60 PSI at fuel rail.

 

My pressure gauge is on top of the fuel filter before the fuel rail. And it is exactly what the repair manual calls for. I checked it with the vacuum line on the pressure regulator on and off and it's dead on both ways.

 

sounds like your map sensor to me... an o2 code cause it to run slightly rich but not like you're describing... I had this happen after my b20 vtec swap... it wasn't the actual sensor it was the tune looking for the wrong sensor... so check and double check your map sensor

 

any numbers on the gauge? you should see fuel returning to the tank from the regulator at idle when you disconnect the vacuum hose, the regulator function is to maintain steady pressure of 40-60 psi,( down from 100 psi supplied by the pump)
so if the regulator fails, the injectors will get full pressure of the pump, which in turn results in too much fuel being released by the injectors into the manifold/cylinders, the plugs get soaked, etc etc, to the point of no detonation.

what is the PSI on the fuel? the pressure cannot be too high nor too low, it has to be right, hence is the fuel pressure regulator.

 

The pressure is 33-35 psi with the vacuum hose connected, and 44-45 psi with it disconnected. Haynes repair manual says 31-37psi and 40-47psi, respectively. So according to them, that should be good. The car is outside and I don't have light to check for fuel in the return line tonight, but I will as soon as I get off work tomorrow.

 

Does it flood and smoke right after you start it up or does it have to warm up a little first? By warm up a little Im talking like 30 seconds.

 

It has to warm up a little(10-15 seconds), but not even 30 seconds. Right at a cold start-up, it does run better.

 

try another temp sensor they can be bad out of the box.
here is how you can clean your injectors (although i dont think it is your issue.)
1. remove the injectors
2. get a harness plug that fits your injectors and wire up a 9 volt battery terminal
3. plug in the injector to your newly made harness.
4. plug in your fresh 9 volt battery
5. spray carb cleaner thru your injector.
6. repeat with 3 remaining injectors

 

its your o2s i would bet like 100 bucks on it. that 15 seconds is how long it takes for a heated o2s to start working, before the o2s is up to temp it is in an open loop mode that relies on pre-programmed fuel trim values, once the sensor gets hot the ecm goes into closed loop and lets the o2s tell it how much fuel to deliver...

2cents...

 

Replaced O2 sensor... still the same problem. It does exactly the same, but my cel is off now.