Topaz L4-140 2.3L HSC (1984)
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)
