How To Check Vacuum Pump

[rvarner]

I have the vacuum pump running all the time as described in the related post "Pump noise under the hood". My pump will never shut off no matter what position the the switch is in. I have looked everywhere short of tearing apart the dash. I know the pump works cause the coolant mixer (green line) will work. I have pinched off the small black line running into the ball and have pinched off the large black line running to the pump. It never shuts off even with the lines pinched. Is there a way to isolate the pump (shut it off-short of pulling the wires) for test purposes?? Thanks
Richard

[rvarner]

I have the vacuum pump running all the time as described in the related post "Pump noise under the hood". My pump will never shut off no matter what position the the switch is in. I have looked everywhere short of tearing apart the dash. I know the pump works cause the coolant mixer (green line) will work. I have pinched off the small black line running into the ball and have pinched off the large black line running to the pump. It never shuts off even with the lines pinched. Is there a way to isolate the pump (shut it off-short of pulling the wires) for test purposes?? Thanks
Richard

[Gary CA]

Richard:

I just replaced the vacuum pump assembly. If you follow the vacuum tube from the "Black Ball" you will find the vacuum assembly. My vacuum assembly is a FORD heavy duty truck part #FOE3HZ-2A451-A / PUMP ASY-VAC. Cost was $208.

The only way to shut it off is to pull a wire. If you have room to get under the coach use a screwdriver and remove the 3 sheet metal screws. I was told this is an important part that creates vacuum for more than the AC controls, it might also create vacuum for engine and air-assist brakes. That's why I drive 300 miles round-trip in my toad from a Flagstaff AZ Ford dealer to another Ford dealer.

Anyone taking a long trip; I would add this vacuum assembly to my tool box because not every Ford dealer carries this part. It is very easy to remove and replace, takes about 15 minutes if you have a part in-hand. If not you might find yourself driving for 5 hours...If I had only known!

[rvarner]

Thanks Gary. Sounds like that part is pretty expensive. How did you test it to see if it really was the pump? I sure don't want to order one unless I'm positive it's bad. Mine is still creating a vacuum and I would think there would be a simple test to check it.
Richard

[SCVJeff]

I started out with the ol' finger blocking test. You should be able to block the output of the ball, or pump and the motor will shut off. I just happen to have a vacuum pump/ gauge checker from a previous MH issue I was chasing, so it was handy to have. But this pump (as far as I know) only supplies vacuum to the dash HVAC solenoids. Unless it's open between the ball and dash control (or the control itself is in trouble) you should be able to get the pump to shut off in some position: Def, Mix, Vent, etc.

As flakey as those little tubes have been, look very closely at all of them because this seems like the norm rather than the exception.

[rvarner]

Thanks SCV Jeff. I have blocked vacuum output with the hose off. I can feel vacuum but the pump will not shut off. I am beginning to believe Gary CA is right and the interior workings of the pump are defective. Will order a new pump, it's only money.

Gary CA. Did you call around for the pump or did you try locating one on the internet? How did you find that number? I wonder if the 04 and 02 use the same pump but probably wouldn't matter anyway. Was Winnebago any help?
Thanks
Richard

[KIX]

Richard,
I've also had the same pump problems and bought the replacement from Ford. Mine had the Ford logo on it and a part #. Ford knew what part by the number I gave them. I paid $203 about 2 years ago in Austin, TX

[Gary CA]

Richard: I just made the drive to pick-up the available pump, I needed to get it fixed and back on the road. Long drive, quick repair.

I did remove the hose from the old unit but did not get vacuum.