F 150 4WD Pickup V8-302 5.0L (1986)
Figure 1 - In-Line Base Timing Connector
NOTE:
Remove PCV valve from grommet locate the crankcase closure hose and disconnect at the air cleaner end (allowing the PCV valve and closure
hose to vent to underhood air during idle fuel mixture check).
C.
Verify that the idle speed control motor and the single wire connector near the distributor (sometimes called the In-Line Base timing connector,
Figure 1) are connected electrically. With the transmission in Neutral, run the engine at approximately 2500 rpm for 15 seconds before each
mixture check. If check is not completed within 60 seconds, repeat this cleanout Step.
D.
Return engine to idle and disconnect idle speed control motor from wiring harness. Disconnect single wire connector near the distributor (Fig. 1).
With the engine idling at normal operating temperature, place the transmission selector in the position specified for the idle fuel mixture check.
Gradually open the propane tool valve and watch for engine speed gain, on the tachometer. When the engine speed reaches a maximum and then
begins to drop off, note the amount of speed gain. (Propane cartridge must be in vertical position).
NOTE:
If the engine speed will not drop off check the propane cartridge gas supply. If necessary repeat Steps C and D with a new propane
cartridge gas supply.
E.
Compare measured speed gain to specified speed gain.*
1.
If the measured speed gain is within specification, proceed to Step G.
NOTE:
The carburetor assembly is equipped with a tamper-resistant idle adjustment feature, the carburetor must be removed from the
vehicle. Refer to Group 24, Powertrain Shop manual for removal of the above feature.
NOTE:
If it is determined that idle fuel mixture adjustment will be necessary, adjust the mixture according to the reset rpm specification.
2.
If the measured speed gain is higher than the speed gain specification:*
Turn the mixture screw counterclockwise (rich) and simultaneously repeat Steps C and D until the measured speed rise meets the reset rpm
specification,* After final adjustment, proceed to Step F.
3.
If the measured speed gain is lower than the speed gain specification:*
Turn the mixture screw clockwise (lean) and simultaneously repeat Steps C and D until the measured speed rise meets the reset rpm
specification.* After final adjustment, proceed to Step F.
F.
The carburetor fuel air adjustment must have the tamper-resistant feature reinstalled. Refer to appropriate carburetor assembly instructions in Shop
Manual, Group 24.
G.
Reinstall PCV valve in grommet. Reconnect idle speed control motor and crankcase closure system, and the single wire connector near the
distributor.
H.
Remove all test equipment. Reconnect all system components, reinstall air cleaner, and tighten the air cleaner wing nut(s) to specification,
*Specified speed gain is 10 to 70 rpm, specified reset is 30 rpm.
Pages 4-65 & 4-66
1987
Carburetors, Fuel Charging Assemblies and Throttle Bodies
4-65
Idle Mixture Setting Procedures
