Anybody have a pic of the vacuum lines on the firewall beside brake booster? The one with one or 2 small lines and a large rubber line on it? Or just know what hooks into the biggest one mine seems to have come unhooked but can't find anything to hook back into it. So I have only defrost no cruise and no 4x4

 

i'd look to see if it's hooked to the vaccum pump, if it is, i'd plug that left over port, and see what doesn't work at that point, and trouble shoot from there.

 

I've followed all the lines and all but that one is hooked up. Havnt plugged it yet. I will try that today. The line that's unhooked looks like it had something hooked into it before and its got a little disk like filter/ water separator maybe. In it.

 

Check this out. ( on my list of things to do )
https://www.dieselbombers.com/5-9l-2...-kit-free.html

 

That disc thing is most likely the check valve.

 

Yea that's on my to-do list too. Gonna check out some cars next time im in the junkyard. But that larger line on the far right of the picture is the one I have unhooked looks like a hard plastic line goes into it I have searched all over for a line unhooked and searched everywhere on the net for a vacuum diagram. Any idea what that line goes too?

 

That line will go to the vacuum pump, located under the injection pump.

 

Ok ill check that thanks for the responses we've had 80 degrees and dry so I have been workin early to late and havnt had a chance to mess with it any more.

 

I'm also having problems with my cruise control and 4x4. Just bought this truck a couple weeks ago and I don't know the first thing about Cummins to start with. The first thing I noticed is that my cruise control doesn't work, the light will come on but that's it. Then I went to use the four wheel drive, and same thing, the light comes on but as soon as I give it a little fuel it pops right back into 2H. Sounds like these problems are pretty common and usually related to the vacuum pump?

Okay, so I checked out the vacuum pump lines and at least from the pump to where it disappears into the fire wall it is all intact, but there are some spots where it is cracking pretty bad, just for the heck of it I wrapped these areas with good ol' duct tape but it made no difference with the 4x4 issue (didn't try the cruise control).

So my question is what now? The vacuum pump has suction but doesn't feel real strong. Can anyone tell me where the line goes once it's through the firewall? The only thing I can think is that is disconnected at the other end.

Any help would be very much appreciated.