91 Escort GT Cruise Control

I have an 1991 Escort GT. The cruise Control can't keep the speed up when going up the slightest hills. When on, I hear a sound like a quiet hiss. My first thought is a vacuum leak but I don't know which hoses are for the Cruise Control. Can anybody help me?

Thanks.

Monte

the escort servo is indeed vacuum driven. A leak in the HVAC (in the dash - so you can hear it, u will never hear it under hood) will cut the 'power' the servo has on the throttle.

Any HVAC leak of course needs fixed, but I have always found it useful to isolate the vacuum feed for the servo with a 1 way valve and then install a 'vacuum ball' aka reservoir on a T with it.

This is REALLY needed if you have any ford model with the 'coffee can' vacuum reservoirs which rust out. (GM V8 and V6 carb models have vacuum balls everywhere. they are being crushed by the hundreds daily so go find a few)

I fixed my cruise. There is a switch under the brakelight switch that is hooked to a vacuum line that goes all the way to the speed control servo. I adjusted that switch closer to the brake pedal arm and the hiss is gone and the cruise is working.

Thanks for the help.

Monte

ok thats the servo dump valve.