Where does fuel pressure regulator vacuum port go?

[DoctorRoboto]

I have a '95 B3000 and have been having trouble with the cabin HVAC vacuum. I have a parallel thread over here about that, been trying to chase down why doors aren't opening and such. But I believe I have a much more major vacuum line hookup problem, courtesy of the PO.

I have been trying to figure out the vacuum situation in the vacuum reservoir, to see where the problem is in supplying vacuum to the cabin for control of those doors. I traced the vacuum supply line for the reservoir to the fuel pressure regulator. Attached is a couple of pictures of the vacuum line routing for those bits. If you look at the red vacuum line, it goes directly from the top of the FPR right into that black spherical reservoir (which does hold vacuum BTW, I tested it with a vacuum gauge I just got). The other end of the reservoir disappears under the blower motor, but I think it's the input to the cabin vacuum controls. So the FPR doesn't seem to be hooked up to the manifold, and similarly, the reservoir is not hooked up to the manifold either.

Is this right? Is the FPR supposed to go straight to the reservoir? From what I've been reading, it seems like both of these thing need to go to the intake manifold, not to each other.

A slightly annotated visual is also included. The red line goes from the FPR to the black spherical reservoir. The yellow line is actually a black hose, and goes (I think) up to the firewall. It's certainly not pulling a major vacuum from the intake.

 

[Rearanger]

There should be a vacuum connection on the DS of the intake plenum. The FPR vac has it's own line (your red one) that attaches to this connection. The FPR should not be connected to the vac reservoir as its vacuum needs respond quickly to throttle opening and vacuum changes.

As well the Vac reservoir also connects directly to this same connection at the plenum with it's own line.

Someone has messed with your setup.

 

[DoctorRoboto]

Okay, I will get some new lines and run two of them from the IM to these two ports. If anyone has a few photos or description of the proper routing, I'd like to see how it's supposed to look.

Is that red line at least a stock component, and it's just hooked up wrong? It has nice 90 degree connectors on one end and some kind of tapered rubber fitting on the other end to go into the vacuum reservoir, seems like it did belong in there at some point but is just not hooked to the right things. Given the length, I'd assume that it went from the FPR to the IM.

 

[Rearanger]

If anyone has a few photos or description of the proper routing, I'd like to see how it's supposed to look.

InTake Plenum connection





Routing Diagram



Fuel Pulse Dampener Connection.

 

[Rearanger]

Is that red line at least a stock component, and it's just hooked up wrong? It has nice 90 degree connectors on one end and some kind of tapered rubber fitting on the other end to go into the vacuum reservoir, seems like it did belong in there at some point but is just not hooked to the right things. Given the length, I'd assume that it went from the FPR to the IM.

All my vac lines are stiff plastic and fit into factory connections. As the photo shows I have some red lines. You may need OEM parts??

 

[DoctorRoboto]

Awesome. But can you make those photos a bit bigger? For some reason they show up tiny, and I can't read that diagram or see the detail on the photos.

I hooked things up and it 'works', there was a capped larger port on the back of the IM, and I routed from that direct to the FPR with a reducer. Then I T'd off the line to the EGR and sent that to the vacuum reservoir. It seems to work, and I have control of the vents for a change. But it looks like you went to some different part of the engine for your vacuum source - not sure where that is, exactly. If you have a larger picture, I can try to line it up.

 

[Rearanger]

But can you make those photos a bit bigger?

Sorry, I thought I had them clickable. Should work now.

 

[Rearanger]

Then I T'd off the line to the EGR and sent that to the vacuum reservoir.

You need to be careful about hooking into vac reservoir. Components needing changeable vacuum (which I think includes EGR) need to be hooked to intake. Holding vacuum to reservoir.

For instance the blend doors are hooked to reservoir so that they hold position and can be closed when engine turned off.

 

[Rearanger]

Here is link to 95 on Ranger Station.

http://www.therangerstation.com/tech_library/diagrams/95-99_Ranger_3-0_vacuum_hose_diagram.gif

 

[DoctorRoboto]

Yeah, but doesn't the inlet side of the reservoir act differently than the output? I'm not an expert, but I'd guess that just because the reservoir stores vacuum, anything on the upstream side of that reservoir is still changing along with the IM vacuum. Let me go check.

 

[DoctorRoboto]

Well, the vacuum manifold doesn't seem to have 6 ports on it, so I'm SOL in terms of being able to copy that visual. I didn't realize that the legs of that diagram referred to separate ports on the VM, but that makes sense. Still, I'm going to have to go with what I've got for now.

Just checked, and the response at the EGR test port is very fast, despite being plugged directly into the vacuum reservoir supply line. It's not going to be much of a difference no matter how I reroute things - maybe a slight difference if I were to move the reservoir supply hose an inch further down the VM than if I T'd it off the EGR line, but i couldn't see it affecting anything.

 

[RonD]

It shouldn't be a problem as long as it is on an intake manifold vacuum line.

Vacuum devices like the FPR, EGR, and Climate control use vacuum.......but don't use up vacuum, they are all sealed systems, if they weren't then you would have a vacuum leak.
FPR is just there to stabilize fuel pressure, engine runs fine without it having a vacuum at all but gets better MPG with it because computer doesn't have to change fuel trims as much if fuel pressure is more stable, 1998 and up Rangers have no FPR, computer cycles fuel pump on and off instead.
So FPR doesn't use or need vacuum any differently than the other devices, a direct connection or T'ed connection wouldn't matter.

Reservoir ball is there because when climbing a long grade the engine vacuum can get very low, this would cause vents in the cab to slowly default to defrost only, while system is sealed there will be small leaks.
So there is a "reserve" of vacuum to hold climate control as set when engine vacuum is low for a long period.
EGR system used to be on the reserve ball as well, only it was a "can" then, lol.

EVAP system and PCV system use up vacuum, these are controlled vacuum leaks

 

[DoctorRoboto]

RonD, you are just all over this stuff. Thanks! And that's Rearanger for the confirmation and helpful visuals, much appreciated.