I replaced the fuel pump, sending unit o-ring about a week ago on my 2006 G35 Sedan. Car died and won't start and had a bad fuel gauge. 3 days later I filled up my car, and started smelling gas on my way home. I thought nothing of it since it was my first time filling up the car since I worked on it. The next day, I noticed a small leak on the ground coming from under the driver side rear door. Grabbed a paper towel and it was gas. So I looked under and noticed a leak coming from the top of the tank. So I opened both unit covers and found the gas is leaking from the driver side sending unit. I went ahead and took everything a part to see if I have installed it wrong. Re-seated everything, drove around and gas still leaking. Took everything a part again, and inspected the sending unit which is brand new oem. No cracks or chip on it. I even went to the dealer to buy another new o-ring seal and even a new lock ring. Installed them the same way and made sure everything is tight, but gas still leaking towards the rear end.

At this point, I have no idea why it still leaking. Any ideas to see if I missed to check anything else?

Thanks appreciate the help!!!

 

Clean everything really good with carb cleaner and let it dry. With the seat out and the inspection cover off let it idle and watch for the leak. Could be the quick connect or a cracked line.

 

What do you mean by cracked line?

 

Those being the rubber hoses and their fitting points.

 

Yea it's not coming from the rubber hoses. It's on the driver side that only has the sensor on it. It seems like the gas is leaking through the black metal lock ring. I replaced that, and the o-ring seal twice. Re-seated everything a few times to make sure its sitting right and tight. But still leaking.

 

Use some permatex ultra black RTV when u put it back together. It should stop the leak.

 

Where should I apply it? Also would it still leak through the top of the lock ring?

 

Im not sure exactly which part youre talking about. But I know the ultra black is a pretty good sealant and wont let fuel through wherever u decided to use it.

 

If you black RTV it you'll probably never get it apart again without bending it up. I used Ultra black on my upper oil pans once and I had to remove them later for a rebuild. I had to use a mini sledge to break them apart. Guess that's why they use grey on those areas Just a warning in case it doesn't work and you have to get back in there.

If you can pressurize the tank you could listen for the leak. Maybe take the lock ring off and check if the oring seated properly. Did you grease or Vaseline the oring before you installed it? I always grease them up good for two reasons. #1 Make it slick so it pops into the groove easily. #2 keeps fuel off of it so it doesn't swell up. (kinda screwed if that happens)

 

I'm surprised the mini sledge worked, I usually go straight for the seal cutter because that's some serious adhesion.

 

Hey man you ever found out how to fix this because I am having the same exact issue word for word with my 2006 g35x. Everytime i fill up my tank the gas overflows and spills everywhere at the gas station any help?

 

Tank overflowing fuel like that is a clogged vent line from the fill neck down to the tank.