Re: 2008 jeep grand cherokee laredo
Welcome to the garage.
Can be several things. A member on here had something alike and changed the fuel pump, which seems to have solved the issue, but he didnīt mention the raw fuel fumes.
For some reason there is too much fuel injected. Does it always start ok when cold? The #1 input for the fuel injection is the MAP. If you have a scanner which shows live data, then you can check the MAP. Switch ignition to run, but not start. Compare the MAP with the local ambient pressure. Also coolant temperature and inlet temperature sensor inputs are used for the injection.There could be a problem with the fuel pressure, so check that as well.
Running rich when warm can be due to a problem with the 1-1 or 2-1 O2 sensors. Check if their voltages change rapdly from 0.2-0.8V. Also check the fuel trims STFT (short term fuel trim) and LTFT (long term fuel trim), which can point to some kind of failure. Both the STFT and LTFT should be in the single digit figures, positive or negative. Double digit figures for prolonged times point to some fault (which can be from a sensor to vacuum leaks)