F 250 4WD Pickup L6-300 4.9L (1982)
Vacuum Delay Valve: Testing and Inspection
Cold Start Spark Advance System (CSSA)
NOTE:
If engine is pinging, perform steps 1 thru 4.
1.
Connect tachometer and start engine.
CAUTION: Do not leave transmission in drive for more than 15 second while performing steps 2 and 4.
2.
With parking brake applied, brake pedal depressed and transmission in drive, accelerate engine and observe RPM at which spark knock or pinging
occurs.
3.
Place transmission in neutral and accelerate engine to 1500 RPM to allow transmission to cool. Repeat this step three times.
4.
Disconnect and plug vacuum advance line from distributor. Repeat step 2 to record RPM.
5.
If spark knock or pinging reoccurred, stop engine and proceed to next step. If spark knock or pinging did not reoccur, the CSSA PVS and/or retard
delay valve (if used) is faulty. Repair or replace as necessary.
6.
Remove spark delay valve (SDV), or vacuum check valve, or spark delay valve and check as described further on.
7.
Using a T-fitting, connect a vacuum gauge to distributor advance hose and disconnect and plug vacuum hose from bottom port of Cold Start PVS.
8.
With engine idling at normal operating temperature, there should be no vacuum reading. If vacuum is obtained, the Cold Start PVS should be
replaced.
9.
Reconnect hose to bottom port of Cold Start PVS and disconnect and plug hose from top port of Cold Start PVS.
10.
On vehicles with a cooling PVS, check vacuum at distributor with engine at normal idle. If reading is 2 inches Hg or less, the cooling PVS is
operating properly. If vacuum reading is greater than specified, disconnect and plug the top vacuum line from the carburetor to the cooling PVS. If
reading is still greater than specified, the cooling PVS should be replaced.
11.
With engine idling in neutral, momentarily open the throttle half way.
12.
Observe vacuum gauge for a quick rise and fall as throttle is opened and closed. If vacuum is obtained, the spark advance system is operating
properly. If no vacuum is obtained, check vacuum line for leakage or obstruction and correct as necessary.
