01 Cadillac Deville P0442
2001 DeVille comes in with P0442 - small EVAP leak. Checked the gas cap. Seal on fuel cap brittle & cracked. Replaced with AC DELCO (GT261). Rechecked the system. Still leaking. Pull out smoker. Can't see any smoke, but could hear hissing @ the gas cap. Take some rubber bands & plastic wrapper & put over filler neck. Rechecked the system. No leak. Defective new factory cap? Bad filler neck? Have a 2003 DeVille sitting here. Remove the gas cap & try it on the problem car. No problem!
So I pay closer attention to new gas cap. Seems it has a smaller tube diameter & fits loose on the filler neck. If you wiggle it, you can sometimes get the system to seal. I ordered a Stant gas cap. It fits just fine & seal good.
Years ago had same problem with a few another 2000+ DeVilles @ the same time. Same AC DELCO cap. Thinking maybe it was a packaging mistake, I tried several caps, but same no-seal problem. I even tried one from the dealer! Back then, even the aftermarket caps weren't sealing. Thinking this couldn't be, so I replace the filler neck on one car. Same problem.
I got a couple of used original fuel caps from the junk yard & swapped in the new seals from the new caps. That resolved my problem. Forgot about the problem until last week.
I would think AC DELCO would know about the loose fit problem by now. Obviously, Stant got the memo.
More likely fuel pump module seal leak. Only can see with pressure and soapy water.
That seems unlikely given that a working gas cap fixed his Deville.
You are correct! Since the fuel pump access cover is in the trunk & easy to access (when the trunk is empty), we pulled the cover, checked for smoke & sprayed soapy water to boot… didn't want to miss anything. Also when the fuel pump seal is leaking, you may also notice stains on the sides of the fuel tank.
Tony- People respond to these threads with obviously out even reading them. Frustrates me, but I just bite my tongue…sometimes.
Rudy, That's supposed to be a secret. Parts cannon ammo is cheap when they are not the ones spending it. 🤞
I’ve had a few fuel fills being bent due to customers leaning on the fuel pump nozzle while filling up. Look at the cap and make sure it’s not contacting anywhere while close.
I have noticed that some AC Delco OE replacement caps of other types are very low quality. Their professional line probably is Stant.
Used to replace a lot of CTS AC DELCO fuel caps. The ratchet part goes bad & it's won't seal.
It just depends on the supplier. Years ago, ACDelco could be trusted for consistent quality. Delphi was spun off (DElco Parts Handling International) some years ago as a separate entity, while ACDelco supplied GM OEM quality parts and offered second or third lines, which some have discovered could be of good or dubious quality. Circa 2000, I was delivering ACDelco training around BC and a part…
Who was OEM for this 2001 gas cap, Martin? The OLD Delphi? My 2002 GM has many Delphi labeled parts....but I know that name means nothing now, with all the switcharoos before/during/after "the bankruptcy era".
No idea Geoff. Usually, everything OEM spec boxed ACDelco was fine, but second lines sometimes didn't look, fit or perform as the OEM supplied parts. I never paid much attention to it while working at the dealership years ago. Large organizations such as GM usually have to have multiple suppliers to meet assembly demand, but OEM spec should have proper form, fit and function, no matter the…
Wow! Thanks Juan. When the OE supply is no longer true OEM it's anybody's guess what might work now. I bet Stant is happy to read this one.
Hi Geoff, Welcome to the world economy. Delphi has become lower quality in recent years. I run into many issues with most aftermarket products trying to pass them self off a genuine. With that, black market parts have been flooding the industry more in recent years.