just bought a 94 mark 8.the rear air bag suspension seems to be over inflated and does not go down.back is higher than when front bags fill up.is there a way to relieve pressure to rear bags and regulate pressure?
Unless this is a self-leveling system,
you should have access to an air valve fitting (Perhaps located somewhere in the trunk) that will allow you to depress the valve stem and thus relieve air pressure from the air bags.
The vehicle is self-leveling and has ride height sensors. The stance is controlled by a series of vent valves, etc. and this is all computer controlled.
There is a diagnostic plug but the catch is you need the special Ford tool (STAR 1 I believe) to access the codes. Here is a link to a company with some info on air ride and I THINK they may have a Star tool to loan out, but it requires a 500 dollar credit card deposit until the tool is used and returned within 10 days.
There is a ride height sensor on the left rear wheel, but not the right. With the vehicle jacked up (the Air Ride switch MUST be turned off before EVER raising the wheels off the ground) you might look at that sensor. It is attached with 2 bolts through a slotted bracket and it’s possible an adjustment here could help; depending of course.
I also have a Mark 8 and recently converted my air ride to coil overs. One of the front bags had developed a slow leak due to age (they dry rot like old tires and belts) and since the prudent, and expensive, thing to do is replace all of the bags I decided to convert to a coil spring suspension.
It was easy and cheap. I used new parts from a kit, but 1994-1997 T-bird parts from the junk yard will also do it.
Hope that helps some. (Love those cars!)