Field reference for fuel system and underground storage tank technicians. 18 entries, taken from the DropTubeBuilder app.
Reference notes from DropTubeBuilder, the offline field tool for fuel system technicians who cut overfill drop tubes, build tank charts and chase dispenser faults. It works with no cell signal, because the sites do not have any.
Get DropTubeBuilder on the App StoreVariable frequency controller for FE Petro IST, IST VS4, STP VS4/VS2, and PMA VS4/VS2 submersibles (2–4 HP). Indoor, non-hazardous mounting. Reset button clears faults; press-and-hold Silence Alarm shows the last 3 faults (F0, F1, F2). SW1 rotary sets pump pressure — position 4 ≈ 32 PSI is the recommended calibration starting point. SW2 sets the controller address in Primary-Secondary setups.
Franklin Fueling Systems MagVFC Installation & Owner's Manual, doc 228001101 rev 8
Under Load — tank empty or wrong HP setting
Low fuel level in the storage tank; obstruction on PMA intake; SW3 Pole 6 set wrong for the pump connected.
Push Reset. Verify SW3 P6 matches pump horsepower (VS2 motor with P6 ON can false-trip in SW1 positions 0–6). Check fuel level — after delivery covers the PMA end bell, push Reset. If still present, suspect an obstruction on the PMA inlet.
Low incoming voltage
Voltage fluctuations or low input voltage.
Push Reset. If it recurs, meter the incoming supply — must be 200–250 VAC. Outside that range, have an electrician correct the supply.
Extended Run
Continuous hook signal for over 60 minutes without a change in flow.
Disconnect and lock out power. With all dispenser handles off there should be NO voltage across the hook terminals — if voltage is present, have an electrician correct it, then verify operation. (SW6 Pole 1 ON disables this alarm.)
Voltage unbalance / capacitor bank
Unbalanced incoming voltage, sudden large load, or failed capacitor bank.
Push Reset. Check incoming voltage and loading. If cleared, watch the unit ~10 minutes; if it recurs, contact FE Technical Support.
Over Speed
Controller operating outside its frequency range.
Push Reset and check operation. If still present, power down 30 seconds, power up, recheck. Recurs → FE Technical Support.
High temperature
Excessive operating temperature inside the controller.
Verify the fan runs (replace if not). Check for heat sources at the mounting location and clear all ventilation louvers, then cycle power. Persists → FE Technical Support.
Locked rotor at startup
Foreign material in the PMA or defective PMA (corrosion after water-ballasted tanks is a known cause).
Push Reset. If it persists: lock out power, pull the extractable, remove the PMA end cap and spin the rotor with a 3/16" Allen key to feel for binding. Binding/damage → replace with a new PMAVS4/PMAVS2 (check the lead assembly for shorted wires first). Very long/undersized motor wiring can show a FALSE LU.
Locked rotor while running
Foreign material in PMA or defective PMA. A partial short (nicked pump wire + water in conduit) reads as high power draw and flashes Lr instead of SC.
Push Reset. If it persists, inspect the PMA as for LU (pull extractable, check rotor for binding, replace VS motor if damaged) and check pump power wiring for nicks/water intrusion.
Upper rail short
Short circuit in field wiring or an internal controller failure.
Push Reset. If it recurs: lock out power, disconnect the STP wires at the BLACK/ORANGE/RED terminals and cap them. Power up — if the display now shows OC, troubleshoot as a wiring short circuit; if it still shows SU, the controller is at fault → FE Technical Support.
Open circuit controller → motor
Broken connection between controller and PMA.
Push Reset. If it persists: lock out power, remove the three motor leads and ohm them pairwise — expect 1.2 ±1 Ω (VS4) or 2.5 ±1 Ω (VS2); any lead to ground must be open. Repeat at the extractable manifold wire nuts to isolate whether the fault is the PMA, the connectors, or the run between controller and pump. Long/undersized wiring can show a FALSE OC.
Short circuit / wrong HP setting
Short in the controller-to-PMA connections, or SW3 Pole 6 set wrong (VS4 motor with P6 OFF can false-trip).
Push Reset. Verify SW3 P6 matches the pump HP. If it persists: lock out power and ohm the three motor leads — 1.2 ±1 Ω (VS4) / 2.5 ±1 Ω (VS2) pairwise, >80k Ω to ground. Shorted at the extractable → replace the STP connectors or the PMA; otherwise suspect the run between controller and pump.
No hook signal present, PMA not running, no fault codes present. Normal at rest.
Displays software revision xx.yy right after reset or power-on. If the display stops on yy, check for low incoming voltage or loose input power connections.
Running and holding the set pressure; Pr and the pressure value NN flash alternately.
Running at its power limit (beyond the pressure-regulate setting).
A Secondary unit in a Primary-Secondary configuration is running.
SW3 pole 1. ON: Mechanical leak detectors or LS500 electronic LLD. OFF: Veeder-Root PLLD (required setting). Factory: ON
SW3 pole 2. ON: Gasoline. OFF: Diesel product. Factory: ON. Specific gravity differs — wrong setting mis-regulates pressure.
SW3 pole 3. ON: Primary controller (Primary-Secondary). OFF: Stand-alone or Secondary. Factory: OFF
SW3 pole 4. ON: Pipe compensation — see manual calibration section. OFF: —. Factory: ON. Poles 4 & 5 must match on Primary and Secondary units.
SW3 pole 5. ON: Pipe compensation — see manual calibration section. OFF: —. Factory: ON
SW3 pole 6. ON: PMAVS4 motor (4 HP). OFF: PMAVS2 motor (2 HP). Factory: OFF. Wrong setting causes false SC or UL faults — set to the pump's horsepower.
SW3 pole 7. ON: Auto-reset of Under Load fault (empty tank) when corrected. OFF: Must push Reset to clear UL. Factory: OFF. Leave OFF in IST-VFC Compatibility mode.
SW3 pole 8. ON: Multiple controllers working together — see manual. OFF: Default. Factory: OFF. Not functional in IST-VFC Compatibility mode.
SW6 pole 1. ON: Disables the Extended Run Alarm. OFF: Extended Run Alarm active. Factory: OFF. Not functional in IST-VFC Compatibility mode — leave OFF.
SW6 pole 2. ON: Primary-Secondary fault shutdown control — see manual. OFF: Default. Factory: OFF. Primary-Secondary / Alternating Circuit configurations only.
SW6 pole 3. ON: IST-VFC Compatibility Mode (talks only to rev 1.5 IST-VFCs). OFF: Native MagVFC Primary-Secondary communication. Factory: OFF. Software 1.18+.
SW6 pole 4. ON: Alternating Circuit: swap submersibles every 30 min on continuous hook. OFF: No alternating. Factory: OFF. Software 1.22+. Helps keep tank levels balanced.
SW6 pole 5. ON: Proportional Alternating Circuit (settable run time per controller). OFF: Not used. Factory: OFF. Software 1.24+ (older manuals: Secondary turn-off, 1.23).
SW6 pole 6. ON: —. OFF: Not used — leave OFF. Factory: OFF. Unit may operate unpredictably if poles 6–8 are ON.
SW6 pole 7. ON: —. OFF: Not used — leave OFF. Factory: OFF
SW6 pole 8. ON: —. OFF: Not used — leave OFF. Factory: OFF
Reference notes from DropTubeBuilder, the offline field tool for fuel system technicians who cut overfill drop tubes, build tank charts and chase dispenser faults. It works with no cell signal, because the sites do not have any.
Get DropTubeBuilder on the App StoreThese notes are a field aid, not a substitute for the governing codes, the stamped drawings, the authority having jurisdiction, or manufacturer manuals. Verify against the current documentation for your installed equipment.