[darterburn]

I've had my '84 LX convertible since it was almost new. It only gets driven about 3-4 thousand miles each year, and seldom on long trips, so the cruise control doesn't get much use. The last time I tried to use it, which was the first time in about a year, it wouldn't hold a constant speed. When set on 70 mph it would hold for a while, then slow to about 55, then speed up to as much as 85 before slowing again. Does anyone know what might cause this?
It's a carburated 5.0 5spd. I put a GT40P engine in it last year, with cam, headers and off road exhaust, and pulled all emission controls off. I wouldn't think any of that would effect the cruise control, but ???

 

[meangreen92]

Check the vacuum line. It's possible that the CC servo is on its way out, too.

 

[speedytang]

Check that the vacuum ball for the cruise holds. The servo can be tested also using a vacuum pump. You can also test the lines with the vacuum pump also. I guess you need a vacuum hand pump. lol

 

[darterburn]

Do I need to have access to the servo in order to test it, and if so, what is the easiest way to get to it? It's apparently located behind the fender well.