Running vacuum test for engine condition, Test results, 2 possible gauge readings are – Actron KAL2512 User Manual

Page 2: Steady low vacuum unsteady vacuum

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NOTE: See Manufacturer’s Specifications.
B.Really low, steady vacuum check for:

• Leaking carburetor flange gasket

• Worn carburetor throttle shaft

• Leaking vacuum lines

• Improper valve timing

• Slow engine cranking due to:

- Battery or cable connections

- Defective starter motor

• Mechanical drag in engine due to:

- Tight fitting pistons in rebuilt engine

- Thickened oil due to excessive

oxidation

C.Pulses unsteady indicates a leaky

condition that affects one or more

cylinders check for:

• Burned or stuck valve

• Intake manifold leak at a cylinder

• Worn intake valve guide

• Broken piston or piston rings
NOTE: A certain amount of even pulsing

is normal, notably on 4 and 6 cylinder

engines, and does not necessarily

indicate a leaky condition.

Running Vacuum Test For

Engine Condition

NOTE: It is possible to get a different gauge

reading than obtained during the Cranking

Vacuum Test For Engine Condition.
1. Using hose supplied, connect

Vacuum Gauge to fitting on

carburetor below throttle plate.

2. Start Engine and let idle until at

normal operating temperature.

Test Results

2 possible gauge readings are:

0

Engine

Vacuum

5

10

15

20

25

30

10

9

8

7

6

5

4

3

2

1

0

1

2

3

4

5

6

7

Fuel

Pump

psi

0

Engine

Vacuum

5

10

15

20

25

30

10

9

8

7

6

5

4

3

2

1

0

1

2

3

4

5

6

7

Fuel

Pump

psi

Steady low vacuum

Unsteady vacuum

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