Gas tank pressure?

Tiny
MERCEDES 380SL
  • MEMBER
  • 1985 MERCEDES BENZ 380SL
  • V8
  • 2WD
  • AUTOMATIC
  • 73,600 MILES
My gas tank is not venting properly. It either has a vacuum or is over pressurized. The fuel pump has been replace 4 times in the last 500 miles.
Sunday, August 31st, 2025 AT 10:21 PM

1 Reply

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
The number one reason for the tank to have pressure is a vent valve failure, here is a diagram of the system so you can see how it works and the vent valve location. I would replace it which should fix the problem. Check out the images (below). Let us know how it goes.
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Tuesday, September 2nd, 2025 AT 8:21 PM

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