90xj-

Hey all. I'm having a issue with vacuum fade under acceleration. I already checked for leaks and there are none. The idle isn't erratic and it starts just fine. It is down on power, and the mpg has gone to the floor. Every time I step on the skinny peddle my part time light goes off and my heater changes to defrost. I wonder could the vacuum storage bottle could be bad? Is there a check valve in the bottle that could be stuck open and allowing direct vacuum flow?

Also my vacuum bottle is different than any I have seen before. It has 2 hoses on it instead of 1, and it looks like a ball and less like a bean. Have any of you ever heard or seen any like this?



The hose set up.




The shape.

Thanks
-John

Radi

I"m pretty sure the check valve is internal to the reservoir. A bad check valve will cause the symptoms you listed. No leak, but no vacuum when accelerating.

The Rooster

I agree with Radi... and that vacuum storage is stock for a 90 jeep xj renix...

CRF99XJ

Not trying to thread jack but my XJ is doing the same thing. So your saying that if I change out the storage ball it may fix the problem?

Radi

Assuming you have no leaks. When you accelerate the engine doesn't create vacuum, without that checkvalve all the vacuum-operated devices drop out momentarily.

90xj-

Thanks guys. Now do they still make both reservoirs? Or just the single hose one? I only ask because I can only find the single hose style.

cruiser54

That bottle is used on numerous other vehicles. GM vans is where I usually snag them from at the JY.

I also relocate the ***** to the underside of the coolant bottle bracket on the rEnix Jeeps. Gets rid of about 8 feet of troublesome vacuum piping.

Radi

I bet it does.

cruiser54

Now that I've re-read my post, I can see why you responded that way. ROFLMAO. I'm not editing it either.

ck1

see if you can borrow or purchase a hand vacum pump and start at the vacum ball and check vacum at every spot the a hose connects...on mine the plastic line running to the ball thru the front core support was rubbing ever so slightly...I checked that line from rt by the battery down to the ball and it had a small hole where it was rubbing on the core support...just a thought
Cameron

cruiser54

Precisely why I relocate the ***** to the engine bay.

The Rooster

is there a write up for the relocation with pictures?

cruiser54

No. If I was a real nice guy, I would go outside in the cold wind and snap a photo. I'm considering doing that.

cruiser54

I'm feeling nice today. Keep in mind that my vacuum reservoir looks different as it's off a ford van. It's the same basic size and has the same mounting holes as the small ball reservoir.

90xj-

That looks pretty easy to do. I'm currently driving back home from Colorado to California and the jeep is acting up big time. I can only go 45ish up any grade and the tranny seems to bog down if I give it any gas at all, even if I drop out of overdrive.

I did check all the lines visually and using starting fluid while the engine was running. I tried switching the lines on the ball and also connecting the lines directly to each other. No change. I can't think of anything other than the ball. If I remove the small vacuum line I can hear the ball sucking air while the engine is running, idk if that is normal or not. I know it loses its vacuum as soon as I kill the engine because it should make a sucking noise when I disconnect the main line from it, and it doesn't.