1993 Jeep Wrangler Engine Vacuum Lines

jeep
wrangler

#1

So on the 4.0 6cyl engine there are two EGR valves on top of the valve cover. The one nearer to the front of the car directly beneath the oil filler hole attaches with a vacuum line to the Air box. Both fittings for this hose are 1/2 inch diameter. So that’s the easy part. I replaced the egr valve due to it being really dirty and hooked up a new hose. Simple. Now for the tricky part. The other egr valve above the oil filler hole, has one fitting connecting to the EGR valve at, naturally, 1/2 inch. The other fitting this hose connects too at the fuel rail is only 1/8 inch. This seems unusual, but i believe it had something to do with the fact that on the 1993 model they used plastic vacuum lines… So anyone have any experience with vacuum lines that knows how to professionally fit a hose that has different sizes on either end of the line?


#2

I believe you are working on PCV hoses.

The front hose is a breather hose, it connects to the air filter box and carries no vacuum. Is it not 1/2" on both ends?


#3

Yeah PCV valve (sorry) and yeah the breather hose is 1/2 inch on both ends or just under that like 3/8. The one i’m having an issue with is the pcv valve at the top of the diagram near the MAP sensor. It runs to one of the vacuum fittings and it starts at the pcv valve at 3/8 and then at the fitting it goes to like 1/4. There is a broken piece of plastic right now on the fitting from when the old plastic line was removed so i just slid the hose over that and clamped it. So i want that to be a little more professionally installed because i think it may be causing a leak. It’s either that, the MAP sensor, or the pcv valve on the breather hose is dirty so i’m replacing that as well but i don’t think that it would be causing a fuel shortage during idle and high speed i think thats more related to the vacuum line that is connected near the MAP sensor so i’m assuming it’s the line that’s leaking. I found something online that might help it’s a connector piece for two different sizes 3/8 to 1/4. So i’m thinking i’ll just use that.


#4

I recently had to get from about 1/2" down to 5/16" - or something like that. I found a barbed nylon splicer/reducer at a Tractor Supply Co store. So you end up with two pieces of hose and that in the middle. It cost about $0.89 or something like that.


#5

On a vehicle that old i would replace all the vacuum lines.

        <blockquote>causing a fuel shortage during idle and high speed i think thats more related to the vacuum line that is connected near the MAP sensor so i'm assuming it's the line that's leaking.</blockquote>

I would look not only at the MAP and line but the Fuel Pressure regulator and lines, since they are both vacuum operated.


#6

May have just found the answer to my own problem here. In case anyone is curious.

http://www.autozone.com/autozone/accessories/Dorman-AutoGrade-1-4-x-1-8-in-dia-hard-vacuum-tubing-connector//N-25ry?itemIdentifier=368597_0_0


#7

May have just found the answer to my own problem here. In case anyone is curious.

http://www.autozone.com/autozone/accessories/Dorman-AutoGrade-1-4-x-1-8-in-dia-hard-vacuum-tubing-connector//N-25ry?itemIdentifier=368597_0_0