1989 K5 Blazer, Cruise control surging

[baclay9]

We have been trying to figure out the cruise control surge on my buddies K5. When you set the cruise at any speed you can feel the power surging. We thought maybe it was the speedo because the needle was jumping a little but we changed it and it still does it.

The surge isn't drastic but you can feel it. Thanks for any suggestions.

[Liddy71]

cable driven it may need lube

[baclay9]

cable driven? I thought it worked off of the little "laser" that gets bolted to the back of the speedo.

[Liddy71]

Iam not sure what year but some use to have the speed cable come up from the trans to a box on the inter fender then a cable from it to the cluster

[tobiahr]

it could also be a vacuum leak effecting the actuator attached to the throttle at the carb

[baclay9]

Originally Posted by tobiahr

it could also be a vacuum leak effecting the actuator attached to the throttle at the carb

We were actually thinking maybe that was it. He bought some vaccumm line yesterday and we are going to try changing some of it today and see iff we can track a leak down.

[Jonboy]

It may also be a leak in the diaphragm of teh servo. Check it with a vacuum pump to see if it holds.

[78 Chevyrado]

My 87 used to do that, so I ended up taking the actuator apart to see what was wrong. I didn't find anything damaged so i cleaned it and closed it back up and then it worked fine. Musta just had a bad seal or something.