Carburetor - Engine Idles Rough/Stalls
Article No. 85-14-10IDLE - ROUGH - 2.3L HSC WITH MODEL 6149 CARBURETOR
STALLS - 2.3L HSC WITH MODEL 6149 CARBURETOR
FORD 1984 TEMPO
LINCOLN-MERCURY 1984 TOPAZ
CALIBRATIONS: 4-25A, D, E, F; 4-26D, E, J, K, S
WARNING: This modification is authorized only for the listed engines. Performing this modification on other engine calibrations is unauthorized and could create liability under applicable federal or local laws.
Rough Idle and/or Stalling may be due to incorrect idle mixture settings or other concerns affecting the Idle Air/Fuel Ratio. The following is a procedure which will help to determine the cause and provides a method for correctly setting Idle Air/Fuel mixture.
1. Verify the integrity of the EEC system by performing the EEC system diagnostics described in the 1984 Emission Diagnosis Shop Manual, Section 18, and if necessary, Section 25.
Figure 13 - Disconnect Vacuum Lines:
2. Verify the vapor purge solenoid function as follows:
a. With the engine off, disconnect the vapor purge vacuum lines at the carburetor and at the thermal vent valve (Figure 13), then blow through the end of the vacuum line that is attached to the carburetor. The vacuum line and purge solenoid system should be unobstructed to atmosphere.
b. Start the engine, and again blow through the vacuum line. The vacuum line and purge solenoid system should be blocked.
c. If the above conditions are not met, verify voltage to the purge solenoid. The electrical connector to the solenoid should receive 12 volts with the engine running.
d. Service the electrical system or replace the purge solenoid as required. Reconnect the purge vacuum lines before proceeding.
3. Verify the feedback solenoid functions as follows:
a. Disconnect the electrical harness connector from the feedback solenoid.
Figure 14 - Vacuum Gauge Reading:
b. Tee a 0-100 inch H2O vacuum gauge (such as Ashcroft gauge number 1190A) into the 5/32" diameter hose between the solenoid and the carburetor (Figure 14).
c. Start the engine and idle. Vacuum should read between 14 and 34 inches H2O.
d. Apply 12 volts to the solenoid, using jumper leads to the vehicle battery. The vacuum should read between 54 and 75 inches H2O.
e. If the vacuum output is not as specified, replace the feedback solenoid (E43Z-9B998-A).
f. If the stalls and/or rough idle concern has still not been resolved, reconnect the electrical connector to the feedback solenoid. Leave the vacuum gauge connected to the system, and continue to Step 4.
4. Determine if the system is allowing the feedback solenoid to adequately control idle fuel/air ratio:
a. With the engine at idle, clamp the hose to the vacuum gauge as required to dampen oscillation to approximately +/- 5.0 inches H2O about its mid reading. The needle should be oscillating about a mid reading range of 16-45 inches H2O.
b. If the mid reading is oscillating within the above range, the carburetor and feedback solenoid are functioning properly and should not need adjustment or replacement. Refer to Step 7 for further diagnostics.
c. If the mid reading is out of range or not oscillating, continue with Step 5.
5. Determine if a carburetor adjustment will allow the feedback solenoid to adequately control idle fuel/ air ratio:
a. Remove the carburetor from the vehicle and remove the steel plug from the idle mixture adjustment screw hole. Reinstall carburetor on the vehicle.
b. Turn the idle mixture screw in, noting the number of turns required to lightly seat the screw. Then turn the screw out to its original position.
c. Start the engine, and adjust the idle mixture screw until the mid reading is in the 26-45 inches H2O range. If the mid reading will not adjust into the specified range, reset the screw to its original position and proceed to Step 6. If the mid reading will adjust into the specified range but the rough idle/stall condition persists, the cause could be due to factors outside of the carburetor feedback control system. Refer to Step 7 for further diagnostics.
6. Use the propane gain procedure to determine if the carburetor is preventing control of idle fuel/air ratio. (There could be a plugged passage, ruptured diaphragm, etc.).
a. Disconnect the fuel evaporative purge hose at the carburetor and plug the hose.
b. Disconnect the Feedback Control Vacuum hoses from the two ports on the carburetor. Attach a hand vacuum pump (Rotunda Tool 021-00014 or equivalent) to the 7/32" Feedback Control Diaphragm port on the carburetor.
NOTE: Take the 5/32" vacuum hose, supplied with the vacuum pump, and attach a short 7/32" hose containing one of the following restrictions:
ATX - .039" Restrictor (#61 drill size) MTX - .036" Restrictor (# 64 drill size)
The restrictors can be fabricated using a drill, sizes listed above, through a Holley Feedback Tube (Part# 14R-1107-40,14R-1107-50,or 14R-1107-60.
c. Disconnect the electrical connector from the thermactor TAB solenoid.
d. Disconnect the PCV hose at the carburetor and cap the port.
e. Disconnect the flexible fresh air tube from the air cleaner duct adaptor. Insert propane enrichment tool, Rotunda Tool T75L-9600-A or equivalent into the carburetor inlet.
f. Apply 6.5 +/- 0.5 inches Hg vacuum to the 7/32" feedback port.
CAUTION: VACUUM IN EXCESS OF 7" Hg CAN RUPTURE THE FEEDBACK CONTROL DIAPHRAGM. CONFIRM THAT THE VACUUM HOLDS STEADY. LOSS OF VACUUM MAY BE CAUSED BY A RUPTURED DIAPHRAGM.
g. With the transaxle in neutral, run the engine at approximately 2,500 rpm for 15 secs. before each mixture check.
h. With the engine idling at normal temperature, cooling fan on, A/C off, place the transmission lever in neutral. Note and record idle speed. Gradually open the propane tool valve, and watch for engine speed gain, if any, on the tachometer. When the engine speed reaches a maximum and begins to drop off, note the amount of speed gain. (Propane cylinder in vertical position. Check propane supply if engine speed fails to rise and fall.)
i. Measured speed gain should be 55-130 rpm (automatic transaxle) or 30-100 rpm (manual transaxle), in which case proceed to Step 7.
j. If the measured speed gain is higher than the speed gain specification, turn the mixture screw counterclockwise (right) until the speed gain meets the reset specification of 80 rpm (automatic transaxle) or 60 rpm (manual transaxle). Repeat Steps f, g, h, and i, setting idle speed as required to the recorded value from step h (do not record a new idle speed each time step h is repeated), until no further adjustments are required. After final adjustment, proceed to Step 7.
k. If the measured speed gain is lower than the speed gain specification, turn the mixture screw clockwise (lean) until the speed gain meets the reset specification of 80 rpm (automatic transaxle) or 60 rpm (manual transaxle). Repeat Steps f, g, h, and i, setting idle speed as required to the recorded value from step h (do not record a new idle speed each time step h is repeated) until no further adjustments are required. After final adjustment, proceed to Step 7.
l. If the speed gain cannot be set to specification, replace or overhaul the carburetor and return vehicle to original configuration.
7. If the speed gain can be set to specification, the carburetor idle system is functioning properly. Rough idle could be caused by a faulty EGO sensor, processor or other factors outside of the feedback control system. Return vehicle to original configuration, reset idle speed to specification, and refer to the FPSC publication "Driveability Service Aids," April, 1984 edition, and TSB 85-9 for further diagnostics.
PART NUMBER PART NAME CLASS
E43Z-9B998-A Fuel Control Solenoid R
ARTICLE SUPERSEDED: 85-9-16
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual.
OPERATION: SP12650E85 - Perform EEC System Diagnostics
TIME: 0.5 Hr.
OPERATION: SP12650E1 - Vapor Purge Solenoid Test
TIME: 0.1 Hr.
OPERATION: SP12650E2 - Service Electrical System
TIME: 0.3 Hr.
OPERATION: SP12650E3 - Replace Vapor Purge Solenoid
TIME: 0.2 Hr.
OPERATION: SP12650E4 - Feedback Solenoid Test
TIME: 0.1 Hr.
OPERATION: SP12650E5 - Replace Feedback Solenoid
TIME: 0.2 Hr.
OPERATION: SP12650E6 - Feedback Solenoid Control Check
TIME: 0.1 Hr.
OPERATION: SP12650E7 - Carburetor Adjustment Verification
TIME: 0.4 Hr.
OPERATION: SP12650E8 - Propane Gain Procedure
OPERATION: SP12650E9 - Replace Carburetor (Inc. Adjustments)
TIME: 0.5 Hr.
OPERATION: SP12650E10 - Overhaul Carburetor (Ind. R & I and Adjust)
TIME: 1.9 Hr. DLR. CODING: Basic Part No. 9510 - Code: N4