I keep getting a Check Fuel Filler Cap light. I've cleaned the mouth of the filler tube. Bought a new Cap, and reset the light. What do I need to do?

What codes are you getting?

I'll guess the 'small emissions evap leak' The gas cap is always first to be suspect, and granted, its the cheapest potential fix, but it'll probably lead you under the car to the vent tube from the cannister close valve to the filler neck, or the valve itself (stuck open due to debris)

report back, so I can check my psychic potential!

It's throwing codes PO455 and P1000

Thats a large evaporative system leak:

Possible causes:

Fuel cap off

Fuel cap seal defective / missing

EVAP system leak (canister damage, pipework damage)

EVAP Canister purge valve to engine purge pipe: blocked, leaking, disconnected

EVAP Canister purge valve failure (stuck closed)

EVAP Canister close valve failure (stuck open)

Fuel tank leak

Canisters and piping look good. Is the purge valve my next step? should I just replace it ?

The canister close valve under the car can be pretty easily removed and 12 volts can be applied to see if it is stuck. If that looks OK, then I would go for the purge valve replacement, which is more difficult to accurately evaluate since it operates on a pulse width modulated signal.

After I clear the code,I may drive it 5 miles ,or 25 miles before the "fuel Cap" lights trips again. Should my next step be to replace the Purge valve?

I would remove the canister close valve from under the car (between the canisters) and inspect it closely. Apply 12 volts to see that it operates properly and check to see that it is not filled with rust or contaminants.

If that checks out, then invest in the purge valve.

Thanks White. You just gave me something to do today.lol I had nothing else planned. We'll give it a shot and see what we find. I'll let you know.

The canister close valve looked very clean, and tested fine. Reinstalled it and went for almost 150 mile drive. We were 90 miles into our drive before the Fuel Filler light came back on. I guess the purge valve is the next step. I'll order one tomorrow.

I've installed both a new purge valve and a canister close valve. After about 70 miles the check fuel filler Cap light came on once again. Suggestions?

At this point it point it might be advisable to take it to a shop to get a smoke test to try to locate a vapor leak.

Vent tube from ccv?

Dropped it off to my buddy's garage to have the smoke test done. We'll get this figured out yet!

Today is 5-6-13.....

any updates ???

Sorry for the slow update.I wanted to make sure that the problem was corrected. The smoke test revealed a Canister pipe had a leak. We've put about 500 miles on her since the repair,and no lights. Thanks again for the help guys.

I changed out my battery a couple of years ago. When I did I didn't put the overflow tube all the way down in the hole to let the overflow drip to the ground. It dripped on my evap canister and the acid burned a hole in it. Could have bought a new one for $350, could have bought a salvaged one for $50 or do what I did. DUCT TAPE!

2001 XK8 Conv.

bump ^