Weak vacuum pump?

[Madurski]

I'm am experiencing some problems with my truck and I think it is vacuum related. I have a gauge, but since I never measured the vacuum before I don't know how much it should pull.



My problem is the cruise control and the ABS/brakes lights are on. The cruise works but it takes a looonnnngggg time for it to engage, it slows down uphills, and it takes a vvveerrryy looonnnggg time for the acceleration button to work. I haven't found any cracks or holes in the hoses (yet) but I'm not sure where all of them go. My environmental controls work just fine.



If anyone has a vacuum routing diagram they could e-mail that would be extremely helpful.



Thanks,



Ron Madurski

 

[Bob Beauchaine]

The vacuum pump is located in front of the PS pump ( both are one unit), You will see a line about 3/8s coming off the vacuum pump - you can pull it off and hook up your guage there. It should read no less than 8 in. Hg/vac. at idle and up to a max of 25 in. Hg/vac. at full throttle. When I tested mine it was a steady 25 in. Hg/vac. all the way through the rpm range. Hope this helps.

Happy trails

Bob

 

[Madurski]

That's exactly what I was looking for. I knew where the pump was located (by following the lines) but I had no idea what a good value would be from the pump.



Thanks,



Ron

 

[paccool]

Ron,



Test the booster for leaks. If you pull the hose off the booster to check vacuum, that will tell you what the pump is doing. If that is OK, I suggest you check the brake booster for leaks. I pulled the hose from the cruise control module and put the vacuum gauge on it. Check the vacuum here. If ok, then the booster should be ok. If low, pull the fitting out of the booster and plug off the hole with your finger. See if the vacuum comes up. If yes, then the booster is leaking. The cruise module can also be leaking and you can test the same way. If the booster is ok, put a piece of hose on the fitting and put the gauge here. Hook up the hose to the cruise module and check vacuum. pinch off the hose or pull and plug, see what the vacuum does.



I'm saying all this from memory. Did this a couple of years ago. Don't have the truck with me today so I havn't taken a fresh look at the setup. May be a little different than described but you should have the general picture.