Vacuum Help ASAP!!!

Reply Subscribe

Thread Tools

Search this Thread

Dec 8, 2005 | 10:15 AM

Grunt0311

Thread Starter

Senior User

Joined: Oct 2005

Posts: 179

Likes: 0

From: Paw Paw, MI

Vacuum Help ASAP!!!

Okay, I posted this question a few months ago, but have done some more research. I have 99 F350 SRW 4x4. A few months ago my vents stopped working, will only go on defrost. Also, my 4x4 won't work unless I get out and lock the hubs in. I assumed a vacuum problem. When I take the hose off that goes from the pump to the canister and plug the end, the pump shuts off. That tells me the pump is functioning as it should. So I pressurized the canister with my compressor, and no leaks. Now I am thinking it is the selenoid mounted on the inner fenderwell next to the pump, Ford part # 6C3Z9H465 BA. I am planning on buying one after work and replacing it, but the part is $51.00 and non-returnable. If that doesn't work I was going to replace the pump, at $135, also non-returnable. Does this sound like what the problem could be? Has anyone else had this problem and replaced these? Did it fix it? I forgot that I also replaced the vacuum lines down to the front hubs as I read somewhere on here that they tend to go bad, and in fact mine were all cracked. I would really appreciate any advice. I hate to blow $$$ that I don't need to, especially at Christmas time with so many gifts to buy. Thanks!!

Dec 8, 2005 | 10:50 AM

Fat Diesel

Logistics Pro

Joined: Aug 2005

Posts: 3,884

Likes: 180

From: Morgan Hill, CA

Did you carefully follow all the vacuum lines under the dash? Seems like some of the problems originate there. They can unplug, etc.

Dec 8, 2005 | 11:07 AM

jeff Heidel

Freshman User

Joined: Sep 2003

Posts: 28

Likes: 0

From: Phoenix, Arizona

I think your assumption is correct, you have a vacuum leak. The vacuum controlled air doors are not working because you have low vacuum. The leak may be coming from the hub since when you lock the hubs the truck runs ok. I would disconnect and plug the lines to the hubs then see if the pump stops, you will have to wait untill the canister empties before the pump will shut off. If that does not work follow the vacuum lines to their control point, disconnecting and blocking off as you go untill you find the leak.

Jeff

Dec 8, 2005 | 12:08 PM

Grunt0311

Thread Starter

Senior User

Joined: Oct 2005

Posts: 179

Likes: 0

From: Paw Paw, MI

I did follow lines under dash, all are connected as far as I can tell. When I manually lock my hubs in, my 4x4 will work but the vents still will not. Thanks!