The distributor is equipped with a fresh air vent system. When the engine is started, vacuum that the engine produces pulls fresh air in from the air intake duct. A constant supply of fresh air is needed within the distributor. An inoperative distributor vent system may cause premature distributor failure.
If the check valve/filter or the check valve is installed backwards the system will not function. Verify flow direction is toward the manifold using a hand held vacuum pump at the check valve and the check valve/filter's ports. Vacuum should hold in one direction and not the other. If vacuum holds or does not hold in both direction, for either component, that component is faulty.
Number(s) below refer to step number(s) on the diagnostic table.
Check for a blocked or restricted vacuum source.
Check for a blocked, restricted or collapsed hoses. Check the connections at the distributor cap for a blockage. Check for a faulty check valve or check valve/filter.
Check for damaged or leaking hoses or connections. Check the seal between the distributor cap and the distributor. Also, check the distributor cap for cracks or other damage.
Step
Action
Value(s)
Yes
No
1
Was the Powertrain On-Board Diagnostic (OBD) System Check performed?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check
2
Does the vacuum not build up or bleed off quickly?
Go to Step 3
Go to Step 5
3
Does the vacuum hold?
Go to Step 4
Go to Step 6
4
System OK
Go to Step 7
5
Repair the distributor vent system for a blockage or restrictions.
Is the action complete?
6
Repair the distributor vent system for vacuum leaks.
7
Replace the faulty check valve.
