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vacuum lines


Well-Known Member
July 16, 2007
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Year, Model & Trim Level
93 Explorer XLT
My 93 Pushrod engine has 2 vacuum lines missing.

The first is the connecter where all the vacuum lines connect (Brake booster cruse controll etc.)

There is no hose near it that i can find.

Also there is another that connects near the missing one but the line is not connected to anything.

This is near the throttle body.

See attached photo



When I cover them with my finger the engine runs smooth and quiet.

When I uncover them the engine sputters and is loud.

Where should theese lines go?

Should I just cap them off or what?

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The one that can clearly be seen in the first picture is capped in my car. I had the same problem about a year ago where the cap must have blown off. I looked all around and couldn't find a hose.

I capped both the lines and she runs great but I can still hear a hiss around the battery and a hiss when i turn it off. Whats the best way to check for vacuum leaks?

To me, that 2nd one looks like it goes to the hoses for the FPR and the hoses to the air box..


there are 2 lines in that harness the second one goes to an adapter that splits it off to the air box and etc

Okay... The second picture is the line for the FPR (Fuel Pressure Regulator) I just reconnected it. It is under the braided fuel line that connects to the fuel rail. The first picture is capped off and remains a mystery. The line from the FPR being disconnected would make it run rich that makes sense considering the fuel spilling out of the exhaust. Thees explorers are filled with little mysteries. Any insight on the vacuum line coming out of the air box (its black with a green stripe) ?

Any insight on the vacuum line coming out of the air box (its black with a green stripe) ?

On my 92 there are 2 going to the air box. The larger one is black with both yellow and green stripes and it goes to a valve on the side of the cold air intake just behind the grill and below the battery. Below a certain temperature (not sure what temp though) it re-routes intake air past the exhaust to warm it before it goes into the air box.

thats correct.. one line from the airbox (doesn't matter which) goes to the flaper valve to allow the exhuast to preheat the air going into the motor.. The 2nd line works its way back to the plenum vacuum source. As it goes back to the vacuum source I believe it T's off to the vacuum for the blend door.