Actron KAL2512 - Manual (Page 3)

A. Steady vacuum reading between 15
and 20 inches indicates a mechanically
sound engine.
B.If unsteady reading increase engine
speed to 2000 RPM:
• If evens out check:
- Ignition and/or timing
- Carburetor mixture adjustments at idle
• If pointer sweeps get larger check for
- Weak or broken valve springs
• If pointer sweeps become smaller
and more rapid check for:
- Carburetor or intake manifold leaks
- Sticky valves
Exhaust Restriction Test
1. Make sure vacuum gauge is connected.
2. Increase engine speed to 2000 RPM
and keep.
3. Note vacuum gauge reading.
4. Look for slowly decreasing vacuum
reading.
• If vacuum decreases check for a
partially blocked muffler or tailpipe.
Positive Crankcase Ventilation
(PCV) Valve Test
1. Unplug PCV valve that was plugged
with tape.
2. Crank engine
• If vacuum drops to half the noted
vacuum then the PCV valve is good.
• If vacuum reading is much lower than
one-half the problem is usually
excessive flow which could upset the
proper carburetor air/fuel ratio causing
rough idling and burned valves.
• If vacuum does not change the PCV
valve is usually clogged.
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
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 vacuum between
15 and 20 inches
Unsteady vacuum reading
Vacuum Drops half the
noted vacuum