Different vacuum readings (1 Viewer)

[arklatex60]

I am getting different vacuum readings at the gas filter port (10 inches) and the a/c idle up port (19 inches). First my gauge was hooked up to the gas filter port and it read 2 inches. I moved it to the a/c idle up port to double check and it read 19. So I removed the gas filter and cleaned quite thoroughly with brake clean. Man I got a lot of goo out of it. Now it reads 10. Any ideas why the difference? Still dirty? Would a low vacuum draw there cause problems anywhere else? By the way I am finishing up a desmog using a jim c rebuilt carb and dizzy and the desmog pdf found here on mud.

 

[OSS]

The gas filter has 3 pipes leading to stuff. The lower BVSV in the thermostat housing connects to it and is bleeding vacuum when the engine is warm. Maybe when measuring vacuum there, if that vac hose is still attached, the gauge is detecting bleed through from the BVSV.
I’d go with the vacuum reading you get at the AC idle up vacuum source at the rear of the manifold.

 

[arklatex60]

Those are good points. I'll probably tee off of the a/c idle up hose. Thanks

 

[CruiserTrash]

Those are good points. I'll probably tee off of the a/c idle up hose. Thanks

For what it's worth, the "gas filter" is available new from Toyota. Sometimes they get so gunked up you can't clean them all the way. They're also available in a 2-port version that I think came on 2nd gen 4Runners. Threads right in to the 2F intake manifold.

 

[arklatex60]

For what it's worth, the "gas filter" is available new from Toyota. Sometimes they get so gunked up you can't clean them all the way. They're also available in a 2-port version that I think came on 2nd gen 4Runners. Threads right in to the 2F intake manifold.

I have it soaking in a jar of Berryman all day. It seems to be doing something. I'll try it out this weekend. Fingers crossed.

 

[CruiserTrash]

I have it soaking in a jar of Berryman all day. It seems to be doing something. I'll try it out this weekend. Fingers crossed.

My approach to my truck is “if it’s $35, why chance it?” Toyota made these parts that have lasted 30-40 years, we’ve gotten our money’s worth out of them and it’s ok if they old part retires.

Other people may feel differently.

 

[arklatex60]

I thought that I would give an update for anyone who may be interested. A couple of days ago I soaked the gas filter in Berryman. Today I took it out of the Berryman and blew nitrogen threw it to dry it out. Reinstalled the part, hooked up the vacuum lines and low and behold....19 inches. Saved myself $35, and maybe kept an old part in service for another 40 years. Thanks to those who gave me advice.