M3xpress

iTrader: (1)

After leaving the gas station a few days ago I pulled into a parking spot to meet some friends. As I got out of the car I noticed there was a bit of fuel on the side of the car under the fuel door.

Cap felt a little lose, took it off, and put it back on till it clicked and it was tight. At the next stop it put out a little bit of gas out of the cap, but not as much as before and as the night went on it seemed like it had stopped.

The next day I wanted to check things out better and noticed that the little door inside the fuel neck looked like it was open. I was able to pull it closed some.

I drove the car a good bit yesterday and half the day today with no issues. I went to get some gas today and after I took the gas nozzle out I noticed the door seemed to have stayed in the same spot and it had not been pushed back to open.

Once I made it back to work I noticed it a put out a few dribbles on the side of the car again. Not a lot but still something.

When I get home I think I can get the little door a bit more closed, but I know I won't be able to get it all the way flush. Is it common for these things to wear out? Does the fuel filler neck have to be replaced to fix this if I continue to have problems?

The tank has been dropped multiple times here lately to deal with a burned out fuel pump, and then a defective new pump, so having another fuel issue and the idea of the tank having to be dropped again is...

2001NBMZ28

'98's are different caps, tanks etc. from '99 and up. Thinking it shouldn't leak outside the cap if the seal is good though? SES on? Should throw evap codes (P0440 large, P0442 small) leak in system. If codes are present bring it back and ask them to do a pressurized smoke check on the evap system.

M3xpress

iTrader: (1)

Been driving it and haven't noticed any dribble lately, but it hasn't had much more than a half tank in it. Today was the first time in a while that I've gotten a little dribble on the side and this was after I put gas in it earlier today.

The SES light is not on.

Is it worth the $10 bucks to get a new Stant cap from Advance and see if it corrects the problem or is the cap fine since it doesn't throw a code?

2001NBMZ28

You can try a new cap but might not be the issue since the tank has been dropped a few times. What do the folks who dropped the tank say? My girlfriend's '98 throws P0440 every couple months - replacing cap hasn't stopped it - and has never dribbled gas either. Make sure you get the correct replacement, a '99 and up cap is different.

pewter2002

iTrader: (4)

Maybe when the work was done on the tank the vent(S) were not put on in the correct order or even at all? Wouldn't surprise me.

M3xpress

iTrader: (1)

I noticed there are two different part numbers on the Advance Auto website for the '98 cap and the '99-02 caps so I'm assuming the difference has been taken into account.

Just recently left with the shop who did the pump about the issue.

Is the door at the top of the filler neck one of vents that you're talking about? Would those had to have been adjusted/removed to drop the tank?

Spartan7

iTrader: (7)

No, there is a vent hose coming off the pump sending unit. It is clipped to the brake line bracket above the rear end.

I'd replace the cap to rule it out. That little door you're talking about is not a big deal, mine hangs open slightly as well. The next thing you might want to do is check all the fuel hose routings, since the tank has been dropped.

LS6427

iTrader: (2)

Bro.....I still have my 1998 factory gas cap. Its almost wacky if one of them fails in 20 years. BUT......it still is possible. Get a new one and see if it fixes the problem. If you're snot getting codes for gas vacuum leaks......its still hiolding.

But they are cheap.....so just do it in case a little gas is getting by.

BUT.....you can't fill your gas tank ANYWHERE near where the gas is actually gettinmg close to touching the gas cap. During hurricane season down here one year I put 19.4 gallons of gas in my 1998 WS6 Trans Am tank and nothing came out. So doing a normal fill won't do anything really.

Its like our radiators.....getting a new cap will cure allot of problems. Its cheap....so try that first. Then report back.

.

M3xpress

iTrader: (1)

^^That's what I thought at first, surely gas is not coming up to the brim of that door.

I just assumed the door in the neck was the problem because the first time I checked around the car everything else seemed dry.

I will try the Stant cap from Advance first and see what happens. I will also check underneath the car again and see if there is something I missed.

M3xpress

iTrader: (1)

Noticed that the rubber ring around my old cap had a bunch of cracks in it, so I went ahead and got another cap.

I got Stant replacement cap that was for the '98 only. It's still getting a little bit of fuel on the side of the car.

It must be in turns or whenever the fuel gets sloshed around, because it doesn't come out all the time.

LS6427

iTrader: (2)

I might get a new cap just as preventative maintenance.....its 13+ years old.

.

2001NBMZ28

To find the leak bring it somewhere and get a pressurized smoke check done.

tecmec

iTrader: (1)

Ever figure this out? I've got the same issue.

LS1 proj

I have the same problem... The plastic piece that the gas feeding tube goes through doesn't seem flush really it's higher on one side then the other does anyone know how to fix it? Iv taken it off and tried a couple times.... Is yours the same way?

tecmec

iTrader: (1)

I'm not sure I understand your issue. But I don't see how that plastic relates to the cap sealing on the filler neck.

LS1 proj

Idisnt know of it would
Push it a little just enough that the oring in the cap couldn't make a good enough seal but I really don't know it was just a guess

JLFIII

iTrader: (1)

So yeah, I have the same issue in my 98 T/A. It seems whenever I fill up my tank with 3/4 or more gas, it "sloshes" when I take turns at normal speeds and I get some gas coming out of the cap.

I just ordered a new cap because that seems like the cheapest and easiest possible solution, but was wondering if anyone who has had this problem eventually found a fix?

Also on another note, I've had to fix my tank for leaks, and was told it doesn't have much life left in it (212+k miles) due to what the mechanic called "soft spots" in the tank. Does anyone make a replacement tank for the 98 T/A's?

JLFIII

iTrader: (1)

Anyone?

eb110americana

iTrader: (4)

Any follow ups to this?

I dropped my tank almost two years ago ('98) to replace the fuel pump and never had a problem until a week ago. The little flap has been open pretty much since I bought the car over 10 years back.

The most recent change is that at a SMOG check they claimed the gas cap was bad and put a new one on about a month or two ago. It didn't start leaking until just recently, but now I always notice fumes coming out of the tank when I drive. I also replaced the evaporative emissions canister+purge valve that sits just ahead of the gas tank about a year ago, but I did notice that the hose is a little kinked and the mount for it isn't the best anymore. Hopefully the canister didn't come loose or the stop functioning.

For now I am inclined to think that the gas cap might be wrong, and just order a new one to make sure they didn't select a 1999-2002 cap. Unfortunately there's no labeling, though it is a GM unit, not aftermarket, so I cannot tell. It does feel like, if I pull on it, that even after tightening to three clicks, there is a lot of in-and-out play, which says to me that it may not be sealing. Seems most of you who tried new caps for this issue had to keep on searching for a fix. Any luck?

eb110americana

iTrader: (4)

Update: I ordered and received my new GM OEM cap from RockAuto (GT299, supposed to replace the original 22616291) and put it on today. It looks identical to the one the shop placed on the car a couple months ago. End result: the car does not leak fuel or fumes. I filled up gas today and topped it off pretty well, then did some healthy driving with plenty of turns that would have definitely sloshed out before. Not even a hint of fuel smell right by the cap when I got out.

The cap still feels loose after being tightened though. there is both lateral play, and in-and-out it feels as if the two plastic tabs are too far in and not quite putting full pressure against the flange. Hopefully this does not mean that this cap will likewise fail at some point when the rubber seal will no longer makes sufficient contact with the filler neck.

Possibilities as to why the first new cap failed and this one works:

1. First cap was defective.
2. Second cap just hasn't failed yet as suggested in the above paragraph.
3. First cap looks the same, but was actually designed for another year car.
4. Both new caps came with short tethers (), so when I saw this with the first one, I complained to the shop that replaced it. He took the old tether off my original (supposedly bad) gas cap and transferred it to the new cap. The tether is held on with a collar that rotates freely in a shallow groove around the outside of the cap. The collar on the old tether is slightly thicker, and is a bit harder to put onto the new cap and it doesn't rotate all that easily. It is possible that this collar was restricting the natural movement of the cap and somehow causing it to bind or not tighten completely.
5. While transferring tethers, the mechanic damaged the new cap with the flathead screwdriver he used to pry them off and on.

I'm still using the too-short tether. I may make an extension for it out of insulated braided metal cable instead of trying to use the old tether from my old cap. If it leaks again, I will update. For now, I am happy the simple fix worked.