Gas Leaking Only After Fill-Up.

[OJmobileII]

Hello, I just purchased a '98 GSX and noticed a gas smell from time-to-time. Smell was not present at time of purchase. Thought maybe it was from running real rich under boost, 720cc injectors + 255lph pump + no tune.

I think I have isolated the smell to only after I fill up. I recently filled up before parking for the evening and put a catch pan down under the tank on the right rear. Came out and checked about 5 hrs later and found about a quart of fuel.

What can cause this kind of leak? I never overfill. I usually fill up around half a tank and the pump usually reads between 6-8 gallons. Could the overfill safety be out on my car? Could there be a hole somewhere? Anyone experience similiar problems?

Haven't had a chance to get under there yet. Will take a look tomorrow, but any heads-up would be greatly appreciated. Thank you.

EDIT: I would like to add, that there is no leakage during fill up.

RESOLVED: Fixed this sometime ago and just wanted to update for anyone searching in the future. Whoever did the fuel pump left that cap almost completely off. Thanks to all that helped out. It is exactly as Toxicangel described here:

Look at the 8th picture in this link http://www.vfaq.com/mods/pump-WB-2GAWD.html
Make sure the plastic ring in on tight.

________________________________________________

Sam C

 

[SOADweskey]

It is probably leaking from somewhere along the filler neck or where the filler neck connect to the tank. If you don't already have a Haynes or Chilton manual you should get one as they both have sections on fuel system regular maintenance and check.

 

[OJmobileII]

It is probably leaking from somewhere along the filler neck or where the filler neck connect to the tank. If you don't already have a Haynes or Chilton manual you should get one as they both have sections on fuel system regular maintenance and check.

Thanks for the quick response. I will make sure to check there. I will hope its something simple, I really don't want to have to drop the tank this weekend.

 

[turbolover10]

I remember right after I replaced my f/p and filled the tank it was leaking out right on to the pavement. I ended up tightening everything back up and never happend again

 

[matthewdesigns]

I had a similar leak on my '96 AWD. It would leak after a fill-up, or when parked at an angle. It ended up being a loose/worn out clamp on the filler neck (the braided looking portion), where it attaches at the tank end. I put on another clamp and have not seen or smelled it again.

 

[CrazyM]

I had this problem on my 90 laser. There was a little 6-8 inch piece of tube that had a hairline crack in it, and would only leak at ABSOLUTELY full.

 

[niles]

I think I have isolated the smell to only after I fill up. I recently filled up before parking for the evening and put a catch pan down under the tank on the right rear. Came out and checked about 5 hrs later and found about a quart of fuel.

I had the same problem a few weeks after my dealer had done the 2G fuel tank recall:

If you fill up your tank with cold gas, the gas is usually colder than the outdoor temperature.
If you now parking the car without using a certain amount (volume) of the gas the pressure inside the tank rises with the temperature of the gas (it extends). The pressure is even higher because there not much air left in the tank.

Now what happened in my case:
The dealer failed to installed the gaskets of the pump unit and the gauge unit the right way. Both sides were leaking: first the pump unit's gasket, a few weeks later the gauge unit's gasket

Check if you have the same problem (under rear seat).
Attention: If you don't reinstall the gaskets immediately they will extend and won't fit anymore until the next day. And use a bit of soapy water to install the caps.

 

[Toxicangel]

Look at the 8th picture in this link http://www.vfaq.com/mods/pump-WB-2GAWD.html
Make sure the plastic ring in on tight.