Gas smell at startup

[Astrak]

92 Eldo 4.9, ever since I have had the car every time I start the engine it smells like gas really bad. I have run diagnostics and I think it is in ECM inputs I am showing that both right and left banks are running rich(left and right should be at 128 they are both at 111) also if I rev the engine in neutral I get a really bad rotten egg smell. Could these problems both originate from bad O2 sensors? Or a bad Cat?

[BodybyFisher]

Have you checked the FPR? It sounds like you are dumping fuel. Pull the vacuum hose off of it and see if you smell or see fuel present. Start the car with the hose off, and see if fuel spits out as you rev it. Lastly, put a hand held vacuum pump on it, and see if it will hold pressure.

Your gas mileage must be poor also, I would imagine

[Cadillac Jim]

When you are done with BBF's advice, check it again. If you still smell gas, check for dirty or leaking injectors.

[Astrak]

Have you checked the FPR? It sounds like you are dumping fuel. Pull the vacuum hose off of it and see if you smell or see fuel present. Start the car with the hose off, and see if fuel spits out as you rev it. Lastly, put a hand held vacuum pump on it, and see if it will hold pressure.

Your gas mileage must be poor also, I would imagine

I don't know what the mileage should be, but since I have had the car I have always averaged 20 to 21 mpg 50mph in town driving. This would just be mostly to work and back which is ten miles and I only hit about 5 stop lights on the way.

[BodybyFisher]

Jim, I initially thought about leaky injectors, but they should induce a fuel trim problem, if I am not mistaken due to a bank to bank imbalance. His O2 sensors are also balanced at 111 each so the L/R bank O2 sensors are 'seeing' the same air/fuel mixture. But they are LOW at 111 compared to where they should be at 128 indicating that a LEAN mixture is being commanded.

An oxygen sensor will typically generate up to about 0.9 volts when the fuel mixture is rich and there is little unburned oxygen in the exhaust. When the mixture is lean, the sensor's output voltage will drop down to about 0.1 volts. When the air/fuel mixture is balanced or at the equilibrium point of about 14.7 to 1, the sensor will read around 0.45 volts.

When the computer receives a rich signal (high voltage) from the O2 sensor, it leans the fuel mixture to reduce the sensor's reading. When the O2 sensor reading goes lean (low voltage), the computer reverses again making the fuel mixture go rich. This constant flip-flopping back and forth of the fuel mixture occurs with different speeds depending on the fuel system. The transition rate is slowest on engines with feedback carburetors, typically once per second at 2500 rpm. Engines with throttle body injection are somewhat faster (2 to 3 times per second at 2500 rpm), while engines with multiport injection are the fastest (5 to 7 times per second at 2500 rpm).

It seems to me that the PCM/ECM is trying to LEAN out the mixture, and it has run out of latitude to do so. I would look at the Fuel Pressure Regulator first

[Astrak]

FPR could be a reason, I haven't noticed any cut-out in power while driving normally except whent he AC compressor is on there is a very noticeable drop in power more so than what should happen with the compressor on. In my Chrysler I had the FPR go bad but it was very noticeable as the engine would cut out while driving unless the pedal was held to the floor.

[BodybyFisher]

I would start there, let us know what you find