My 2003 Chevy Monte Carlo was running just fine then my hubby had a flat tire and then the car wouldn’t shut off all the way, then it started and wouldn’t stay running. I’ve replaced the EGR Valve, throttle position sensor, camshaft sensor, O2 sensor, the ignition lock and cylinder and switch, and the shifter assembly inside the car. After replacing all of this the car will start but won’t stay running unless you have your foot steadily on the gas, the moment you remove your foot off the gas it dies. I can smell gas under the hood when we try to keep it running. I’m stumped and at my wits end with this car. What else could it be?

 

First thing I would check would be the FPR. If you have the non-supercharged engine and that part is bad, it can cause an explosion and the symptoms match. First with the car off, pull the vac line going to it and see if it has fuel in/on it. If not, pull the vac line with it running and watch for it to spit out fuel.

Without the fuel smell, I would suggest checking the MAF, MAP, and IAC. Well, I still suggest that but maybe check the evap system first. Not sure if that malfunctioning would cause running issues.

 

FPR. That’s the fuel pressure regulator correct?

 

Yes.

The smell of fuel always worries me...

 

How are you diagnosing that all of these parts need replaced? Its such a random group of things that it sounds like shotgunning parts as I can't imagine those all went bad together. If thats accurate, my next purchase would be a basic scan tool that can read live sensor data and a basic multimeter. Take a look at the sensor data to see whats happening - is a sensor flat lined, is it adding or taking away a bunch of fuel, etc etc. Without any kind of diagnostic data, we'll just be guessing at a cause.

 

I have a scan tool, check engine was on prior to this and it was for the O2 sensor, the temperature sensor and the fan circuit malfunction. This car has also had no parts replaced on the engine since 2003 everything was OEM. I had planned on changing everything already and have had some of the parts for awhile. The scan to did not say anything about any part that I replaced since this started. I am going to check on the MAP sensor.

 

My guess is a bad MAF sensor or a big vacuum leak.