'69 Vacuum Door Locks
 

I just repainted my inner doors and jambs, and as a bonus, I found and fixed a leaky vacuum line to my door locks. Now they actually work.... but only when the car is running. Is this normal?

I thought that, due to the canister and check valve, that the vacuum supply should remain when the engine is shut off (at least for awhile).

Just curious if I need to look for another leak or bad check valve, or if it's normal.

Otherwise, I'll just need to get in the habit of unlocking before I shut the car off...

I don't have a grand prix, but I would hazard a guess you "should" be able to get at least two actuations out of the vacuum resevoir with the engine off. There is probably an internal check valve on the vacuum can that is bad or a leak in any one of the lines or switches. You could try and install a universal check valve on the engine side of the vacuum resevoir. The other thing might be higher lock mechanism resistance due to age requiring more vacuum than when new to operate. You could tee in a vacuum gauge to check what the vacuum of the lock system does when the engine shuts down, or if it maintains what the draw is when the lock switch is pressed.

My '67 T-bird has the vacuum door locks too and I only get one actuation after the engine is shut off. I attribute this to high resistance in the lock mechanisms as the locks wiggle just a bit but won't click over.

Thanks for the reply, I thought that should be the case. I'll look upstream to the check valve, and maybe put some clamps on the line to the canister.