Check Fuel Cap light

Can anyone tell me what I should be looking at besides the fuel cap if the check Fuel cap light is on? Its not my vehicle but I sure would like to help the owner. There is no Check Engine light on. Any typical cause of this? Thanks. ( Its a 2003 xlt)

Do you have access to a scan tool that will also report manufacturer-specific diagnostic codes? Just because the CEL is not illuminated does not mean that it won't have evaporative emissions codes or pending codes.

I'd suspect you have a vent solenoid system issue that is preventing the fuel tank from maintaining the correct pressure. It could be an issue with the fuel tank pressure sensor as well. Was a fuel filter or fuel pump recently replaced, by chance?

-Rod

Unfortunately i dont have a scan tool to put on it. I'm about 300 miles from home and just trying to help someone with the problem. There has been no recent work done on the fuel system. I thought perhaps there was a typical or most frequently found cause of this besides just the cap that I can look at. Thanks.

OK- I found a disconnected vacuum hose that goes to the evap solenoid. After restarting the light is still on. Do I need to reset the PCM or does it take time for negative pressure to build in the tank?

Is there an Auto zone or Pep Boys near? They will read the codes for free.

Thanks for the reply. There is an Autozone nearby - but the Check engine light is not on- only the check fuel cap light. Will that set a code?

Update---The light went out after the first warm up cycle.

Yes the check fuel cap will store a code.

Thank you for your help.