Vacuum Line Strategy

[backporch]

I have a 99 Ranger XLT with 4wd calif emissions and no EGR. The previous owner added manually locking front hubs. I noticed a lot of vacuum lines that were damaged when I replaced the engine.

Does anyone have knowledge of what the smaller vacuum lines do and which of the canisters by the headlights are important? I am looking to purge or cap of whatever is not needed. At a minimum I need to keep the fuel pressure regulator line and whatever works the climate control.

The brake booster and pcv are not issues. The line coming from under the throttle body I see is for fuel tank/vapor canister.

Any suggestions on how to clean this whole setup?

 

[RonD]

The vacuum reservoir, there's only 1, is usually by the headlights, lower down

It needs 1 vacuum line from the intake manifold, source for vacuum
There will be another vacuum line on it that runs to the Firewall this is for Vent control in the cab, i.e. defrost, panel or floor air flow direction
This is usually a Black hose/line
At the firewall in the same location will be a Grey hose/line it runs to the Heater hose control valve in engine bay, its activated by MAX AC

On the black line from reservoir to firewall there should be a "T" for the PVH hub solenoid, this can be removed or plugged if PVH is not used any more

But here is where it can be complicated, lol.

Some reservoirs have a built in Check Valve, some have an in-line check valve, this holds vacuum in reservoir when vacuum in intake drops, i.e. when you accelerate

So follow the line from the intake manifold down to the reservoir, see if there is a "T" or device any where on that line
If there is it may be an inline check valve and may "T" off to the PVH solenoid follow it to see.
It could also be just a "T" if it runs to the Fuel Rail's Pulse Damper.

There should be a vacuum hose diagram on the rad support

Without EGR system there are only a few things that need vacuum

Brakes and PCV
Cab vent controls(reservoir) with Heater hose valve
Pulse Damper, 1998 and up Rangers
Air Pre-heat vent(on cold air intake), vacuum line runs to air filter box and then down to pre-heater valve

EVAP system
PVH system on 4x4s

 

[backporch]

RonD. Thanks

I will have to chase down the lines when I get back to the truck around new years. From my pictures I can see the intake manifold has a connector by the brake system vacuum that has a splitter to two small lines. One, a yellow tube, goes down by the frame by the driver's side front wheel. The other heads rear toward the firewall. Another line comes from somewhere around the passenger side (red) to the fuel rail. There is a gray line from a heater hose valve by the passenger side and goes down and disappears in the A/C system components. I thought I saw the vacuum reservoir on the passenger side.

I willl check the label on the truck and see what else I can learn. Thanks for the tip on the reservoir providing backup vacuum. I would have never thought of that.

 

[RonD]

Yes, reservoir makes sure cab vent settings stay as they are when engine vacuum changes.
If you only have Defrost then there is no vacuum present for the cab system, broken hose or ??
If vents change to Defrost when you accelerate then reservoir is not holding any vacuum reserve

PVH hubs and EGR systems also used the reservoir as they need consistent vacuum levels to operate properly regardless of intake vacuum levels

 

[backporch]

Looks like on my setup, the small vacuum lines start by the upper intake manifold, next to the large brake booster line. The line splits to a yellow and red line. The yellow goes to a vacuum control/test gizmo above the wheel well on the driver's side. The red line is routed back and around the upper intake manifold, where it connects to the fuel rail near the schrader valve and also splits to connect to a black line that finds its way by the windshield washer tank. That black line goes to the vacuum reserve tank under the passenger side headlight.

Somewhere around that point it also Ts off to a small length of hose that is missing and probably would have fed the passenger hub. The line also follows the brake line under the engine to provide vacuum for the driver's side hub... I guess. Looks easy enough to just cap off the line where it makes that T right before the vacuum reserve tank.