7
Troubleshooting
Problem
Slow Flow (STP-MLD+ is in the tripped position only
allowing 3 GPM or less ow rate)
Possible Causes
1. System leak (i.e., line, dispenser, STP / IST, etc.)
2. Thermal contraction
3. No time delays in dispensers or not set correctly
4. Incorrect STP-MLD+ version
5. Tank empty / air in lines
6. Power to STP is off or defective dispenser switch
signal (hook)
7. Defective MLD
Actions
1. Visually inspect all areas for leaking product.
2. Insert a pressure gauge in shear valve.
3. Cycle the pump to conrm that the system is
holding pressure. If pressure is not holding,
conduct a line test through the STP / IST. If
there are any system leaks, repair, then retest
the system. If system has no leaks (line or
submersible), thermal contraction may be a
possible cause. Continue to the next step.
4. Test for thermal contraction per FE Petro
®
Technical Bulletin TB-001. If thermal contraction
has been veried, continue with the next step.
5. Find the opening time (test cycle) of the STP-
MLD+. Follow step 14 and time how long it takes
from when the submersible pump is turned on
until it reaches full pump pressure. The STP-
MLD+, STP-MLD+ AG, STP-MLD+D and STP-
MLD+ B models typically take 2 - 4 seconds. If
the test time is not within these specications, it is
possible that there is a line leak, air / vapor in the
line or not using the correct STP-MLD+ model for
the installation, thus causing the opening time to
increase.
Cycle the power and time the number of seconds
it takes for the solenoid valve in the dispenser to
“click” open, this is an audible indicator and usually
easy to hear. This time must be approximately two
seconds greater than leak detector opening time.
Consult dispenser manuals for solenoid time delay
installation or adjustment.
6. If problems continue, contact Franklin Fueling
Systems Technical Support at 1-800-984-6266.
Problem
Not catching a 3 GPH leak at 10 PSI
Possible Causes
1. Air / Vapor in system
2. STP-MLD+ installed incorrectly
3. Using the incorrect STP-MLD+ version
4. Testing procedure
5. Defective MLD
Actions
1. Make sure all air / vapor in the system has been
purged, see step 11. If no air / vapor is present
continue with next step.
2. Make sure STP-MLD+ is installed correctly:
a. STP-MLD+ must be installed in leak detector
port on submersible pump manifold or adapter
tee housing, making sure the O-ring is present
and not damaged
b. The vapor tube must be installed and vented
back to the tank port from the STP-MLD+
c. Make sure there are not any in-line check
valves between the dispenser solenoid valve
and the STP-MLD+
d. If a manifolded system, only one submersible
pump can turn on at a time during the leak
testing cycle
e. There must be less than 12 feet of static head
in the system
3. Make sure the correct STP-MLD+ model is being
used for the application (product and piping), see
the model list on page 3.
4. Is the leak testing xture calibrated correctly (3
GPH leak @ 10 PSI). Has the STP-MLD+ been
fully tripped before testing, see step 16.
Note: If your STP-MLD+ does not operate correctly or
there are any questions concerning installation
or service, please contact Franklin Fueling
SystemsTechnical Service at (800) 984-6266.
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