got a 2001 f150 5.4 4wd crew cab and threw a code reader on it just to check things out and the computer will not check the evap system,code reader shows yellow light and is saying it has not run a system check on the evap,its been two weeks and same thing,any ideals. thanks in advance.no codes or check engine light though,seems to run good,getting about 12.5 miles to gallon.

 

i dont have an awnser buy my truck has an evap circut error. Good luck. i have tired changing the canister in the back and the valve in the front and nothing worked. No idea on how to find out where the break in the wire is

 

No CEL? Cap and filler in good condition? Vacuum lines hooked up? Evap can in good condition, hooked up correctly? No smell of gas fumes in engine compartment or near evap can? No fuel leaks?

If you can clear those and there are no codes, I'd go Alfred E. on that one and "What, me worry?" it.

Back to step one. Pull the fuel cap and see if you get a CEL. If so, run your check and see what you get. Replace and see if it clears.

Good luck with it.

 

Probably a fuel cap not completely sealing, or a leak in the filler neck somewhere.

You can have the cap pressure tested (sometimes for free at smog stations) because that's usually the culprit. Or try clicking it 3 times.

 

If you're simply noticing that the evap monitor has not run and you don't have any emissions inspections in your immediate future, I have only one bit of advice: Don't screw with it!

It is not a fault; it is simply test that has not yet run. Depending on your weather and driving patterns, it may not run for weeks or even months. This is completely normal in the absence of any fault code indication.

Steve