Vacuum Pressure Testing

[Wags391]

I would like to test my engine for vacuum pressure. I rented the tool. What can i do from there?

[blazes9395]

I don't know if this is TBI engine or a CPI engine. Either way, locate a vacuum port and connect your guage there, start the truck up and watch the gauge and record your findings.

[Wags391]

It is a TBI engine. 92 S10 Blazer, 4x4, 4.3L Z.

Vacuum findings:

Pressure at manifold intake: a steady 19.

What is the measurement name?

Any other tests I can do to make sure all vacuum is good?

[MT-2500]

19-20 range is good vacuum.
It is called inches of HG inches of vacuum.
Some gauges read in mm hg and some in g cm but I like it in of vacuum better.
Most vacuum gauges have a green range for good and a red range for bad.
lower vacuum inthe 15-17 range is late timing or a egr valve open or vacuum leak some place.
A flickering vacuum reding is a bad valve amd a engine miss will lower vacuum.

A good cat stopped test can be run with a vacuum gauge to .
check vacuum at idle and then at 2000 rpm.
If vacuum drops at 2000 under idle the exhaust system is restricted.

Also a vacuum gauge on the dash can help get better gas mileage.
Some older cars had one in dash for gas mileage improvement
Keep it in the green 19-20 range for good gas mileage.
I have had it bring gas milage up and over 5 MPG more.
MT