1972 w108 Fuel Door Stuck. Need Help.

[Baxterdown]

My 1972 280SE 4.5 didn't come with a fuel door. I found one on Ebay and bought it. The door came with everything. I installed it after I painted it and connected the pneumatic lock line.

The guy I bought the car from had told me that the doors didn't work because they were connected to the pneumatic switch in the back of the fuel door. When I drove the car for the first time after the install, the locks started working. Also, the fuel door locked. I thought, very exciting!

Now, the fuel door is stuck locked and I cannot open it to save my life! -- Needless to say, I cannot get gas either

Am I doing something wrong? Should the locks be in some specific position for the fuel door lock to open? If not, how can I open the fuel door?

Help please,

Jose

[Idle]

It has been a long time since I have been inside the back of a 108, but I seem to recall two removable panels, inside the trunk, on the back side of the car on either side of the fuel door.

I think if you remove these panels you will see a way to grab the lever going over to the latch that is holding your fuel door shut. If I recall correctly the vacuum piston for the latch is behind the panel on the right hand side.

Look against the back wall, between the taillight housing cut out and the 'tunnel' that the fuel inlet pipe runs under. The panels should be there and easily removed with either a ten or eight mm socket.

[Baxterdown]

UPDATE: This morning I decided to open the passenger door from the outside. The rest of the locks didn't pop up, but low and behold the fuel door unlocked!

I unplugged the line on the fuel door vacuum piston as a precaution. I don't know if my locks are not working correctly or if I'm doing something wrong.

Without an owner's manual, I'm lost :-(

Jose

[Idle]

This is another area I have not dealt with in a few years, but it is possible to get the vac locks messed up and out of sync with each other. I once referred to this as their being 'out of time' but that is not really accurate.

There is a fix for this but I found it seemed to always take care of itself; at least it somehow it got back in time.

To some folks this is an easy repair. Just not me. Post again with the heading of 'needed to sort out vacuum locks', describe your problem, and someone will have the answer.

And I used to disable the gas door vac switch myself. It was just to risky to keep it functional.

[Tomguy]

The lock for the fuel door only gets vacuum when the system is locked. It sounds like your system is getting vacuum when unlocked. I guess you can test it by locking the doors & seeing if the fuel door can be opened. If this is the case, it's merely fed into the wrong line at that panel in the trunk that Idle spoke of. I ASSUME your trunk locks with the doors and unlocks with them. The only way to test though if you unplugged the fuel door lock is to plug that line. Also: Good luck not having any ruptured 40 y/o rubber diaphragms!