Fuel Door Vacuum Diaphragm: How to get at it?
 

Car: 1989 260E

I have a vacuum leak in what I assume is the diaphram that locks/unlocks the fuel door. All the door locks and the trunk lock work. There is hissing/leakage in the fuel door area when locking the car doors, but not when unlocking. The fuel door itself stays locked, and I have to manually pull the plunger to unlock it when refueling.

This seems like an easy fix, but the assembly is behind a piece of structural metal in the trunk. Before I amuse my neighbors by crawling upside-down into my trunk to get at it, is there an easier way to tackle this?

Also, a completely unrelated question:

Is it normal for the SRS light to stay on for a second or two after starting the car?

Pull out the plastic trunk liner on the right hand side of the car and you'll have no problem at all. It will take a bit of maneuvering and bending, but be persistant. Note that some parts of the liner go into a "lip" of the body around the tail lights, which hold it firmly in place.

It is normal for the SRS lamp to be lit for a few seconds after start up. On my '86 560 it stays lit for a full 10 seconds (just what it calls for in the book).

I have the same problem, only that the latch is unlocked all the time after I pulled the vacuum line off. In my vehicle it is easy to get to the unit that has the plunger. My question is, how does one fix the leak. If you know how to do it, I am ready for instructions . . .

Thanks,
Luis
91 300TE4Matic

Speedy:

Thanks for the scoop. I started pulling some of it but stopped when I got to the tail lights, since I did not realize how it was secured there. You wrote:

"It will take a bit of maneuvering and bending, but be persistant."

Are you referring to me or the plastic liner?


Mike:

Thanks. I read here that if it comes on during driving, that indicates a low voltage condition, and I was beginning to worry about that.

You are correct, if the light comes on while driving, it could be indicative of a low voltage - less than 10.1vDC- situation. Could also be a problem with the SRS system too, but likely a voltage problem.

You'll need to bend and flex the plastic liner a bit. It's pretty flexible, and you yourself will have to manuever, along with the plastic liner! Have fun!

OK, I can see the unit with the red plunger and plastic housing. Now what? Apart from yanking it of f the car, what do I need to to get at the diaphragm inside?

The diaphragm inside is most likely not the problem. It is probably a tear in the rubber that surrounds the actuation rod of the vacuum element.

Speedy,

Thanks. Now could you translate that? :)

The leak is immediately behind the plunger. If I push it a bit, the hissing stops and the locks immediately open/close. So, does anyone know how to remove the plastic assembly in there?