Last night doors wouldnt open when driver key turned. Trunk wouldnt open but gas door was unlocked. drove home and expected engine not to turn off but it did and doors operated properly. Was a cool night of 49 degrees. what could it be ? havent had issues with this???

You have a vac leak. Vac leaks always get worse when the temps fall. All the rubber and plastic shrink a bit. With the car running you provide enough vac supply to run everything. But once the car sits a bit enough vac leaks out to prevent the system to work properly. Do some searches here on vacuum leaks. There is a tone of info about fixing them. You door lock system is probably leaking at one or more connections or actuators.

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you dont think there was something weird in that the gas door wasnt locked?

The fuel door actuator is controlled by vac for locking and is spring loaded for unlocking. So when you lock the doors the vac system pulls the lock closed for the fuel door. When you unlock the doors, the fuel door actuator uses the spring to unlock the door. The rest of the locks, both lock and unlock, are controlled by vac. With all that said. If you loose the vac in the door lock system from sitting or a leak, once the vac is reduced enough the fuel door will unlock, but the rest will stay locked. The open side is spring loaded so that you can't ever accidentally lock it, and end up locking it for ever.

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ok thanks for clearing that up. Do you know what retailer that sells vac gages is "HF"?

How did you come to that conclusion without knowing the model vehicle in question? That is certainly the wrong conclusion for some models. And it suggests a poor design if it is accurate for any model.

Probably read my profile

Not according to the "Recent Visitors" roster.

The fuel door lack actuator on an '84 300D is dual acting. It isn't spring-loaded to any position. There is a manual unlock feature in the trunk in the event that vacuum won't unlock the fuel door.

If your fuel door doesn't lock, that would be a good place to start looking for a leak.

The early 123s are spring loaded, and only have one vac line going to them. I guess they changed it somewhere along the line.

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HF probably means "Harbor Freight". There was a recent post on the benefits and durability of various vacuum gauges and Mity-Vac equivalents.

And I think you're talking about an '84 300D.

Post # 5 has a good diagram.

http://www.peachparts.com/shopforum/showthread.php?t=160169

That diagram is not correct for an '84 300D.

what is different about the door lock diagram on an 84?

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