Problem found while searching for vacuum leak

'92 Limited, 160K
I was looking for a vacuum using 5-90's suggested method of fogging a cold running motor's vacuum lines and intake manifold with carb cleaner. I purchased a cheap can of the cleaner and it was actually more of a spray versus a "fog" and the wind wasn't helping matters.
I knew that I was looking for the spray/fog to being sucked into a line and a raise in rpms. No vacuum leak was detected using this method but, when I sprayed/fogged in the area that is indicated in the photo I would have a significant drop in rpms. I resprayed all areas of the intake several times and spraying the indicated area resulted in the rpm drop every time.
Does anyone have an idea why this is happening or if, it is even something to be concerned with?

FYI, the vacuum leak turned out to be small because my AC will go from the defrost mode to vent mode in under a minute of the engine running.

Was the leak in the tube that attatches to the valve cover? I can't tell from the photo. I have a high idle problem i am trying to locate a vacume leak.:smsoap:

Could be the connector on the fuel injector. With the engine running, pull the connector off and see if you get about the same rpm drop.

1989cherokee said:

Was the leak in the tube that attatches to the valve cover? I can't tell from the photo. I have a high idle problem i am trying to locate a vacume leak.:smsoap:

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I didn't take that tube into consideration when I placed the arrow. I was pointing to the general area of the fuel injector connection. I never did find the leak. I just replaced the vacuum resovoir that the PO yanked out and left the vacuum hose unplugged when he installed a JCR front bumper.
I only checked my vents blowing right after I started the engine and since they were blowing out the defrosters I figured I had a leak.

Saudade said:

Could be the connector on the fuel injector. With the engine running, pull the connector off and see if you get about the same rpm drop.

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Sounds very similar to what I was having happen. I guess the spray was possibly shorting that injector out?

That's what I was thinking given your description. If you pull the injector connector off and the engine runs similar to when you spray it, it may be just the fluid shorting the injector out. Since the stuff evaps quickly, it shouldn't last long.

Carb cleaner tend to cause a drop in rpm when sucked in. Starter fluid should kick it up. I think you simply found a leak.